Malassezia ecology, pathophysiology, and treatment

Malassezia ecology, pathophysiology, and treatment Abstract Malassezia are lipid dependent basidiomycetous yeasts that inhabit the skin and mucosa of humans and other warm-blooded animals, and are a major component of the skin microbiome. They occur as skin commensals, but are also associated with various skin disorders and bloodstream infections. The genus currently comprises 17 species and has recently been assigned its own class, Malasseziomycetes. Importantly, multiple Malassezia species and/or genotypes may cause unique or similar pathologies and vary in their antifungal susceptibility. In addition to culture-based approaches, culture-independent methods have added to our understanding of Malassezia presence and abundance and their relationship to pathogenicity. Moreover, these novel approaches have suggested a much wider-spread presence, including other human body parts and even other ecosystems, but their role in these arenas requires further clarification. With recent successful transformation and genetic engineering of Malassezia, the role of specific genes in pathogenesis can now be studied. We suggest that characterizing the metabolic impact of Malassezia communities rather than species identification is key in elucidation of pathophysiological associations. Finally, the increasing availability of genome sequences may provide key information aiding faster diagnostics, and understanding of the biochemical mechanisms for Malassezia skin adaptation and the design of future drugs. Malassezia, biodiversity, mycobiome, skin, antifungal, disease mechanisms Introduction Malassezia are lipid dependent basidiomycetous yeasts that inhabit the skin and mucosal sites of humans and other warm-blooded animals. They are a major component of the skin mycobiome, based on both culture-based and culture-independent methods that used ITS length polymorphisms assessed by polymerase chain reaction (PCR),1 ITS meta-barcoding, and whole genome shotgun metagenomics.2,3 Various Malassezia species occur on human and animal skin as commensals, and they are associated with multiple skin disorders, such as pityriasis versicolor (PV), Malassezia folliculitis (MF), seborrheic dermatitis/dandruff (D/SD), atopic dermatitis (AD), and psoriasis.4 Use of catheters for parenteral nutrition can lead to Malassezia-caused bloodstream infections in immunocompromised patients or premature infants.5,6 A recent molecular phylogenetic study using six genes suggested the genus is deeply rooted in the Ustilaginomycotina with a sister relationship to Ustilaginomycetes and Exobasidiomycetes. Hence, the genus was assigned as its own class, Malasseziomycetes.7 These findings were confirmed by a phylogenomics approach based on complete genome sequences of 24 Malassezia isolates from 14 species.8 For many decades, the genus consisted of only two species, the lipid-dependent M. furfur and the apparent lipophilic M. pachydermatis. Since then, many more species have been described, initially using the D1/D2 domains of the large subunit of the ribosomal DNA (LSU rDNA) and the internal transcribed spacer regions (ITS) 1 and 2 (including the 5.8S rDNA).9 More recently, additional loci were added, including chitin synthase-2 (CHS2), β-tubulin, and translation elongation factor 1 alpha (TEF1).10–12 The phylogenomics study mentioned above used 164 core eukaryotic genes and identified three main species clusters: Cluster A consisting of species known mainly human skin, that is, M. furfur, M. japonica, M. obtusa, and M. yamatoensis; subcluster B1, with the most abundantly occurring human skin inhabitants M. globosa and M. restricta; subcluster B2 consisting of M. sympodialis, M. dermatis, M. caprae, M. equina, M. nana, and M. pachydermatis; and Cluster C that forms a basal lineage with M. cuniculi and M. slooffiae.8 Since then, three new species were described, namely, M. brasiliensis and M. psittaci from parrots11 and M. arunalokei from human skin.12 Thus at present the genus comprises 17 species. Phylogenetic relationships of these 17 species based on D1D2 domains of LSU rDNA are shown in Figure 1 and are largely in agreement with the previous phylogenomics data. Figure 1. View largeDownload slide Phylogenetic tree of the currently accepted 17 Malassezia species based on sequences of the D1D2 domains of the LSU rRNA gene, inferred using the Maximum Parsimony method with 1000 bootstrap replications. Tree 1 out of 5 most parsimonious trees (length = 377) is shown. The consistency index is 0.531250, the retention index is 0.689922, and the composite index is 0.470319 for all sites and 0.366521 for parsimony-informative sites. The tree is drawn to scale, with branch lengths calculated as number of changes over the full sequence. There were a total of 516 positions in the final data set and the evolutionary analysis was conducted in MEGA7.169 Figure 1. View largeDownload slide Phylogenetic tree of the currently accepted 17 Malassezia species based on sequences of the D1D2 domains of the LSU rRNA gene, inferred using the Maximum Parsimony method with 1000 bootstrap replications. Tree 1 out of 5 most parsimonious trees (length = 377) is shown. The consistency index is 0.531250, the retention index is 0.689922, and the composite index is 0.470319 for all sites and 0.366521 for parsimony-informative sites. The tree is drawn to scale, with branch lengths calculated as number of changes over the full sequence. There were a total of 516 positions in the final data set and the evolutionary analysis was conducted in MEGA7.169 Rapid and accurate identification of Malassezia from clinical samples is of importance for correct diagnosis and treatment. Traditionally, identification of Malassezia has been culture based using morphologic and biochemical features, such as utilization of Tweens and cremophore EL, catalase activity and growth at different temperatures. These conventional methods showed limitations with regards to differentiation between closely related species, are time consuming, and have a high error rate.13 In routine clinical laboratories, Malassezia-related disorders and infections likely are underdiagnosed as standard nonlipid supplemented media, such as Sabouraud glucose agar (SGA), do not support Malassezia growth, and delay correct identification and treatment. Likewise, the absence of species identification limits epidemiological knowledge regarding Malassezia-related disorders and infections.14,15 Several improvements have been made in Malassezia identification. An overview regarding available molecular tools was published by Cafarchia et al.14 With the recent addition of two PCR-based methodologies,16,17 including identification of 11 species directly from patient samples,17 the range of identification tools was further expanded. Application of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification of Malassezia isolates15,18 removed the need for DNA extraction, requires relatively low consumable and reagent costs, and has a short turnaround time. Unfortunately, spectra of most species have not yet been included in available commercial databases. Finally, the number of available genome sequences of Malassezia species is increasing rapidly and offers a valuable resource for development of targeted nucleic acid based diagnostics. As whole genome sequencing becomes more affordable, comparison of full genomes for identification and epidemiology may soon be within reach. Biodiversity and ecology Culture-independent tools for examining complex microbial communities occurring in and on the human body opened opportunities for detection of species that would otherwise be missed using culture-based methods, due to slow or fastidious growth or the lack of appropriate conditions resembling the natural habitat. Originally, human microbiome studies mainly focused on prokaryotic inhabitants of the human body, but fungi have recently received more attention. Some older studies referred to in this review were performed before general application of molecular methods and employed phenotypic methods, such as microscopy and physiological characteristics for isolate identification. We include those studies as they significantly contribute to our understanding of the diversity and role of Malassezia yeasts on the human and animal body, but it cannot be ruled out that over time with the further application of molecular diagnostics the emerging epidemiological picture may evolve. Table 1 gives an overview of all currently known species, with their taxonomic cluster denomination (also see Fig. 1), most common hosts, and known disease/disorder associations in both humans and animals. Table 1. Overview of all currently described Malassezia species with their taxonomic cluster denomination (see Fig. 1), main hosts and main known disease/disorder associations in both humans and animals. species  Taxonomic cluster  Main hosts  Main known disease/disorder associations in humans  Main known disease/disorder associations in animals  References  Malassezia furfur  A  Man, bovine, elephant, pig, monkey, ostrich, pelican  Systemic infections, PV, D/SD    5,9,59,93  Malassezia brasiliensis  A  Parrot  -  -  11  Malassezia yamatoensis  A  Man  SD, AD  -  9,61  Malassezia psitaci  A  Parrot  -  -  11  Malassezia japonica  A  Man  AD  -  57  Malassezia obtusa  A  Man  D/SD, AD  -  9,93  Malassezia nana  B2  Cat, bovine, dog  -  otitis  93,97,98,99  Malassezia caprae  B2  Goat, equine  -  dermatitis  44  Malassezia sympodialis  B2  Man, equine, pig, sheep  Systemic infections, PV, D/SD, AD  otitis  9,26,42,43,93  Malassezia dermatis  B2  Man  AD    9,27,45  Malassezia equina  B2  Equine, bovine  -  dermatitis  44  Malassezia pachydermatis  B2  Dog, cat, carnivores, birds  Systemic infections  otitis, dermatitis  9,64,93,94,95  Malassezia globosa  B1  Man, cheetah, bovine  PV, D/SD, AD  otitis  9,26,93,100,101  Malassezia restricta  B1  Man  D/SD, AD  -  9,27,32,35  Malassezia arunalokei  B1  Man  D/SD  -  12  Malassezia cuniculi  C  Rabbit  -  -  93  Malassezia slooffiae  C  Man, pig, goat, sheep  D/SD  otitis, dermatitis  9  species  Taxonomic cluster  Main hosts  Main known disease/disorder associations in humans  Main known disease/disorder associations in animals  References  Malassezia furfur  A  Man, bovine, elephant, pig, monkey, ostrich, pelican  Systemic infections, PV, D/SD    5,9,59,93  Malassezia brasiliensis  A  Parrot  -  -  11  Malassezia yamatoensis  A  Man  SD, AD  -  9,61  Malassezia psitaci  A  Parrot  -  -  11  Malassezia japonica  A  Man  AD  -  57  Malassezia obtusa  A  Man  D/SD, AD  -  9,93  Malassezia nana  B2  Cat, bovine, dog  -  otitis  93,97,98,99  Malassezia caprae  B2  Goat, equine  -  dermatitis  44  Malassezia sympodialis  B2  Man, equine, pig, sheep  Systemic infections, PV, D/SD, AD  otitis  9,26,42,43,93  Malassezia dermatis  B2  Man  AD    9,27,45  Malassezia equina  B2  Equine, bovine  -  dermatitis  44  Malassezia pachydermatis  B2  Dog, cat, carnivores, birds  Systemic infections  otitis, dermatitis  9,64,93,94,95  Malassezia globosa  B1  Man, cheetah, bovine  PV, D/SD, AD  otitis  9,26,93,100,101  Malassezia restricta  B1  Man  D/SD, AD  -  9,27,32,35  Malassezia arunalokei  B1  Man  D/SD  -  12  Malassezia cuniculi  C  Rabbit  -  -  93  Malassezia slooffiae  C  Man, pig, goat, sheep  D/SD  otitis, dermatitis  9  Note: AD, atopic dermatitis; D/SD, dandruff / seborrheic dermatitis; MF, Malassezia (pityrosporum) folliculitis; PV, pityriasis versicolor. View Large Presence on the healthy human skin The relative abundance of fungi on human skin was found to be low compared to bacteria, but Malassezia yeasts were identified using culture-independent methods as the most abundant skin eukaryotes representing 50%–80% of the total skin mycobiome.2,3Malassezia species predominated on all sampled body sites except foot. Eleven Malassezia species were identified with M. restricta being predominant in the external auditory canal, retroauricular crease and glabella, and M. globosa on back, occiput and inguinal crease. All the remaining species were observed scattered across other body sites and with lower frequency. Fungal diversity was more dependent on body site than the individual, but as similar species distributions occurred 3 months after the initial sampling this suggests temporal stability of site-specific Malassezia communities.2 Reanalysis of these metagenomic datasets using a more complete set of Malassezia genomes demonstrated the presence of 12 species, with M. restricta and M. globosa by far the most abundant, distantly followed by M. sympodialis.8 Most studies surveyed whites of Western descent. A high throughput ITS1 sequencing analysis of 40 asymptomatic Chinese subjects in Hong Kong revealed 90% of the sequencing reads as M. restricta, distantly followed by M. globosa with 5.3%.19 Another study investigating 40 healthy Japanese subjects using a real-time PCR approach, showed that the Malassezia skin mycobiome differed by sex, body site, and season. Generally, in male subjects, M. restricta and M. globosa were most predominant, followed by M. dermatis, M. furfur, and M. sympodialis. In female subjects M. globosa and M. sympodialis were most predominant, followed by M. dermatis, M. restricta, and M. furfur.20 Nevertheless, a major sampling bias is present in skin mycobiome studies to date and future studies need to take this into account. Malassezia skin colonization begins immediately after birth and increases until 6–12 months of age.21 Colonization then remains relatively low until just prior to puberty, when sebaceous gland activation provides a better habitat and Malassezia populations rise to a stable level.4 Recent metagenomic evidence suggests that skin colonization varies according to age and puberty22 and hypothesized a protective effect due to increased Malassezia colonization in adults preventing colonization by more pathogenic species, specifically dermatophytes and other more pathogenic species found more commonly in children. Occurrence in human skin disorders and systemic infections Host factors such as gene-induced variation, environmental conditions, lifestyle, hygiene, and the immune system can cause shifts in skin microbial communities associated with disease.23 For example, molecular studies of temporal changes in skin mycobiota of Japanese Antarctic expedition researchers and astronauts showed a temporal change in colonization levels with different proportions of Malassezia species during periods of increased stress and inability to bathe or shower. Fungal diversity decreased during time in space, whereas colonization of Malassezia species increased.24,25 Oh et al. reported a significant decrease in community diversity as an indication of skin disease, but it remains unclear whether such changes occur at all taxonomic levels.3 Malassezia species have been associated with a number of skin conditions, including PV, a MF, D/SD, AD, and psoriasis.26,27 In a 26S rDNA-based pyrosequencing study of Japanese SD patients Malassezia was the most abundant fungal genus at both lesional and nonlesional sites. At lesional sites M. restricta predominated, and at nonlesional sites M. globosa and other species were detected but did not differ between sites.28 A recent culture-based study of individuals in India applying multiple molecular methods for species identification confirmed the predominance of M. globosa on scalps of control subjects, whereas on the scalps of SD patients the abundance of M. globosa was closely followed by M. restricta and M. furfur.12 Based on both phenotypic and PCR-based studies M. globosa is the species most frequently associated with human disease and linked to various dermatological conditions including PV and D/SD and it occasionally occurs on animal skin.1,26,27,29–33 M. restricta is the second most common species on healthy and diseased skin, particularly of scalp, neck, face, and ears27,31 and is associated with D/SD and AD.1,32,34–36 It was abundantly found on healthy skin but significantly more abundant at SD sites.28 A culture-independent study comparing healthy, nondandruff with dandruff scalp of French subjects found M. restricta as the most abundant fungal species in both but with a slightly higher colonization level on healthy scalp (97% vs. 84%).37 M. sympodialis is the third most abundant species on healthy human skin but appearing with significantly lower frequency when compared to M. globosa and M. restricta.8 It is also known from PV, AD, the skin of an AIDS patient, the auditory tract of a healthy 33-year-old male, and various animals. It must be noted that the majority of these findings are based on physiological, not molecular, identification.26,27,29,38–41 Occasionally, M. sympodialis is also found to cause systemic infections.42,43 M. caprae has been described from healthy skin of goats and equines44 and is less frequently found on human skin.8M. dermatis has been identified with low frequency from both healthy skin and lesions of AD patients.8,27,45 Utilization of culture-based methods identifies M. furfur on various body sites including human skin, blood, and urine. However, culture-independent studies found M. furfur on skin only rarely, with low frequency and abundance.1,2,8M. furfur has been identified from deep-seated infections, such as blood, urine, and vagina, often associated with immune compromised patients, or from septicemia in neonates that received lipid supplementation via catheters.5,46–52M. furfur was isolated from the skin of preterm-infants in a neonatal intensive care unit (NICU), with a prevalence varying according to gestational age, admission to the NICU and length of hospitalization.53,54 An Italian 1-year survey of yeast mediated fungemia in 290 neonates and 17 pediatric patients (age <16 years) using MALDI-TOF and sequencing for species identification resulted in eight cases (2.8%) in which M. furfur was identified as the causative agent. From all patients with M. furfur bloodstream infections the species was also isolated from skin.5 Based on multiple methods, such as PFGE, AFLP, and rDNA sequence analysis, considerable intra-species variation was observed and it has been suggested that a specific AFLP genotype is more frequently involved in deep-seated infections.55,56 Another study evaluated catheter-associated M. furfur strains and found that all isolates recovered from blood cultures and catheter tips belonged to the specific subtype I-3.52 M. japonica is a rare species isolated from healthy human skin of a Japanese woman and AD patients.57M. obtusa has been identified from human groin, the nasal vestibule, and human AD but also from animals.58–60M. yamatoensis is known from SD and AD patients as well as healthy human skin.27,61 During a recent survey of SD in India, a new species M. arunalokei was found on scalp and in the nasolabial folds of both healthy subjects and D/SD patients.12 Based on mycobiome investigations, M. pachydermatis has been observed in the sputum from asthma patients62 and in the nasal vestibule of healthy subjects and patients with allergic rhinitis (AR).60 The species causes catheter-related septicemia in neonates that receive lipid supplementation,29,51,55,63–70 and it has been associated with sepsis and bloodstream infections in immunosuppressed adults.71,72M. pachydermatis is considered zoophilic and is only rarely isolated from human skin.4,8,73 However, it may colonize the hands of pet owners and when PCR was used as the detection technique the prevalence of hand colonization was found to be high (i.e., 93%).74 A possible zoonotic infection route was suggested when pet dogs were identified as a source for transmission of the species to neonates via the hands of health care workers.68 The in vitro production by Malassezia species of Aryl hydrocarbon receptor (AhR) indolic ligands from tryptophan changed our views on the biochemistry of these species. An array of bioactive indoles is produced by Malassezia species. The significance of this observation was expanded when it was associated with M. furfur pathogenic potential and was also shown to happen by the other, more common Malassezia species. Furthermore, these indols may also be formed in vivo as they were found in significantly higher quantities in SD skin scales as compared to healthy controls. Malassezia yeasts both in vitro and in vivo produce potent AhR ligands, that is, formyl-indolo [3,2-b] carbazole (FICZ) and indolo [3,2-b] carbozole (ICZ). The ability to activate the AhR receptor and thus modulate down-stream effects places Malassezia yeasts within two significant pathophysiological pathways, mediation of ultraviolet damage and modulation of the host immune response. These observations, together with the anatomic co-localization of Malassezia yeasts with basal cell carcinoma, led to the hypothesis that they could be implicated in skin carcinogenesis.6,75,76 More studies are needed to gain a better overview of the abundance and role of Malassezia species in the microbiome of healthy and diseased skin of male and females from various ethnicities, different locations, climates, and life styles. It will be especially important to consider long-term (years) longitudinal studies of lesional and healthy skin among genetically related humans.77 Presence in other human body sites A mycobiome analysis of the nasal vestibule of AR and healthy subjects identified 69 fungal genera of which Malassezia was predominant. At least six species were found in all subjects: M. restricta, M. globosa, M. sympodialis, M. slooffiae, M. dermatis, and M. pachydermatis. One sample contained M. cuniculi and M. obtusa. M. restricta represented the vast majority (>86%) in both subject groups. At the species level, two AR subjects showed a notably higher diversity compared to healthy individuals.60 Another study characterized the sinus fungal communities of 23 chronic rhinosinusitis (CRS) patients and 11 controls. Malassezia was the most prevalent fungus and detected in all patients and controls.78,79 Presently available data suggests that Malassezia species are commensals of the nasal cavity, but any role in AR and CRS needs further clarification. Conflicting data exist regarding the oral microbiome. Malassezia were reported to be present with high abundance in the oral microbiome of six subjects, suggesting it may be a prominent oral commensal,80 but reevaluation using more Malassezia genomes failed to confirm this result.8 Culture-based studies and one culture-independent study also failed to confirm the presence of Malassezia in the oral microbiome.81,82 Dupuy et al. suggested that the unexpected findings may be related to the use of an improved harsh cell lysis method,80,82 but this fails to explain why Malassezia were not found in a reanalysis of their sequencing data. Malassezia was also found a dominant oral mycobiome inhabitant in a leukemia patient with mucormycosis.83 In a study that characterized the microbiome of human root canal infections, Malassezia was the second most frequently identified fungal genus after Candida spp., albeit only in two out of six analyzed teeth and with a low abundance.84 With respect to other body sites, two studies found Malassezia spp. in sputum samples of cystic fibrosis (CF) patients but with lower abundances than Candida spp.85,86 Finally, Malassezia species have been found in stool, but more research is needed to clarify whether they belong to the commensal human gut mycobiota.87–90 Malassezia on animals and other habitats Malassezia have been isolated from a variety of animals, including cats, dogs, horses, goats, pigs, and rabbits,91–93 both as commensals and linked to diseased skin. M. brasiliensis and M. psittaci, two recently described species using sequencing analysis of three loci, originated from parrots in Brazil.11M. pachydermatis is the most frequently isolated species from skin of all animals investigated, except rabbits and goats. M. pachydermatis has a high intraspecies diversity, and certain genetic subtypes may have host specificity.94,95M. slooffiae has been reported from bovines, goats, cats, and healthy pigs, but these findings were mostly based on phenotypic identifications.91,96 A sequencing-based study showed that M. caprae was primarily isolated from healthy goats, and M. equina mainly from healthy horse.44 Using sequencing and other molecular methods M. nana has been identified in the ear canal of cats with otitis externa, in cows with and without otitis externa from Brazil,97 in healthy and diseased cats from the UK and Spain,98 and it has been suggested to be the predominant Malassezia species occurring in ears from horses.99 Using phenotypic identifications, M. globosa has been encountered on skin and healthy or otitic ears from cows and on horses that are either healthy or suffer from dermatomycoses.96,100,101M. sympodialis was the most common species found on healthy cattle in Brazil100 but has to a lesser extent also been isolated from healthy equines and other animals.59,96,100,101M. furfur has been isolated from various animals, including elk, elephant, ostrich, goat, dog, cat, and, more frequently, from cattle and equines.59,96,100,101 Most studies describing Malassezia species from animals are culture- and phenotype based, and further culture-independent surveys are needed to compare with the Malassezia communities occurring on humans. Malassezia species were originally thought to be specifically associated with mammalian hosts, but culture-independent studies revealed they may occur in a much broader diversity of habitats, including terrestrial and marine ecosystems such as deep-sea sediments, (Antarctic) soils, corals, sponges, nematodes,102–104 and cone snails.105 Furthermore, Malassezia DNA was detected from soil nematodes in Central European forests, and it has been hypothesized that nematodes may serve as a vector for Malassezia species.106 In a Brazilian study that investigated 45 cows with bilateral otitis nematodes were found in the ears of all subjects and Malassezia yeasts in 69% of the ears, suggesting a possible relationship between nematodes and Malassezia yeasts.107 Finally, in a recent metabarcoding survey on the fungal microbiome of the olive fruit fly, Malassezia was identified as one of the core associated fungi, albeit with low relative abundance.108 More research is needed to clarify the presence and role of Malassezia species in these and other habitats and their possible interactions with other members of the microbial communities and their vertebrate and invertebrate hosts. Advances in comparative genomics To date, the complete genomes of 29 Malassezia isolates have been reported, including 14 species and multiple isolates of the most common inhabitants of human skin, that is, M. globosa, M. restricta, and M. sympodialis,8,109M. pachydermatis, the most common veterinary species,110 and M. furfur, a species that causes most invasive infections and sepsis.8 These studies also included comparison to divergent fungal genomes, indicating features that define the Malassezia genus. Malassezia genomes are compact and well adapted to a specific ecological niche, as evidenced by loss of multiple common fungal gene families and multiplication of others.111Malassezia have a propensity for gene turnover, and the losses and gains are focused on gathering of necessary nutrients from a sparse environment via secretion of large families of lipases, phospholipases, aspartyl proteases, and other enzymes for degradation of skin. Interestingly, comparison of Malassezia to other fungi resident on humans or plants emphasizes “niche specific evolution.”111Malassezia express multiple secreted hydrolases, similar to Candida albicans, another opportunistic human skin pathogen. Candida is not phylogenetically related to Malassezia but its enzyme repertoire also aims to degrade proteins and fat. Similarly to Malassezia, Ustilago produces a set of secreted enzymes for degradation of their local host, but as Ustilago is a plant pathogen the enzymes target degradation of plant specific proteins, cutin, and waxes.8,112 All Malassezia have lost the main enzymes required for lipid metabolism, including fatty acid synthase (FAS), Δ9 desaturase, and Δ2, 3enoyl CoA isomerase.8,111,113 Therefore, they cannot produce fatty acids themselves but need lipids from the environment for growth. Comparative genomics coupled with phenotypic characterization also led to the conclusion that M. pachydermatis, previously thought to be lipid independent and lipophyllic, is actually lipid dependent along with all other Malassezia species. Comparative genomics also revealed 13 Malassezia-specific functional domains, mainly containing genes of unknown function. One example of a gene gain event is that of a single gene, belonging to the PFam domain PF06742 with unknown function, which is conserved in all Malassezia but absent in any other sequenced Basidiomycetes, implying a gene transfer event which predates the genesis of the genus.8 The gene is functionally expressed in M. globosa and its transcription regulated. A second potentially horizontally transferred gene was predicted to be a catalase that matched the PFam domain PF00199. This catalase may be potentially adaptive as it may protect Malassezia cells from their own secreted hydrogen peroxide generating proteins.8 Finally, another Malassezia HGT is the acquisition of flavohemoglobin A from the bacterial genus Corynebacterium, increasing NO resistance.114 These gene families have undergone multiple lineage-specific duplications and then further divergence. The most parsimonious explanation for the genus-wide variation in these gene families may be related to each species’ niche-specificity. Malassezia genomics also revealed they are likely to mate,8,109,111 which may increase their virulence as a result of higher genetic diversity.115,116 The structure of the mating loci suggest pseudo-bipolar mating in all Malassezia where the sequence assembly is strong enough to support structural determination of the region.8,117 Isolates belonging to M. furfur show significant genomic and phenotypic divergence, including isolates with: significantly larger genomes; duplicate copies of multiple genes; and differing karyotype patterns, taken together suggesting a hybridization event.8,55,111,118 Ongoing studies are attempting to disentangle the complexity of these M. furfur isolates and other genetically diverse species, such as M. globosa and M. pachydermatis. Epidemiology and pathophysiology of a complex relationship Malassezia yeasts are eukaryotic fungal skin commensals that must cope in their cutaneous niche with stimuli and perturbations that originate both from the host and the external environment. In addition, host susceptibility is critical.119,120 Thus, from the point of view of human pathology we may consider Malassezia as pathophysiologic effectors acting within a narrow, yet omnipresent transitional (intermediary) zone positioned in between the “self” body compartment, the skin, and the “non-self,” ‘outer’ environment (Fig. 2). Moreover, Malassezia populations occurring within the “transitional zone” are dynamically modified by and also respond to homeostatic reactions of the underlying skin (Fig. 2). In this view, we should not adhere to the concept of pathogenic versus apathogenic Malassezia species as fundamentally understood by the Koch postulates. On the contrary, we should address the impact of the metagenome (secretome, proteome) functional plasticity of the diverse Malassezia species and their constituting populations occurring within an anatomical area and the relevant impact they have on the skin of susceptible individuals with or without excess yeast proliferation, as is the case in PV, and D/SD and AD, respectively. Figure 2. View largeDownload slide Schematic representation of the interaction spectrum between Malassezia, the skin and the environment. Note: AD, atopic dermatitis; D/SD, seborrheic dermatitis /dandruff; PV, pityriasis versicolor. This Figure is reproduced in color in the online version of Medical Mycology. Figure 2. View largeDownload slide Schematic representation of the interaction spectrum between Malassezia, the skin and the environment. Note: AD, atopic dermatitis; D/SD, seborrheic dermatitis /dandruff; PV, pityriasis versicolor. This Figure is reproduced in color in the online version of Medical Mycology. In PV, there is a population burst of Malassezia which proliferate abundantly under favorable environmental conditions (e.g., enhanced heat, humidity). Reversing the aggravating disease conditions can promptly resolve PV without any specific therapy.121 Moreover, in this condition Malassezia cells massively acquire a distinctive hyphal morphology that probably denotes the profuse availability of nutrients,122 which does not only secure the opportunity of the yeast to reproduce freely but also their ability to spread on the skin surface and perhaps to mate with cells from distinct populations of neighboring yeast settlements, for example, from adjacent hair follicles. This would be suggestive of a condition analogous to microbial biofilms. Furthermore, from a clinical point of view, the almost 80% relapse rates after antifungal treatments is disappointing as it only temporarily reduces the colonizing yeast numbers without removing the underlying environmental cause. The pathophysiology of PV lesions includes minor changes in skin barrier function123 or even a potentially protecting UV-filtering action of the Malassezia biofilm.124 The observation of useful skin adaptations as a consequence of Malassezia proliferation further underscores the concept of a pliable, physiological ‘transitional mantel zone’ that enables a gradual transition between skin surface and environment. This ‘zone,’ is by nature “external” to the human body, yet it is also an area of significant compositional plasticity as the diverse effects of the underlying healthy or diseased skin could decisively modify it. Regarding the impact of Malassezia in AD and D/SD, Malassezia induce skin disease through two—not mutually exclusive but potentially interacting—induction mechanisms, namely, allergic and irritant pathways (Fig. 2). In AD, a sensitization state against Malassezia antigens seems to be almost universal. An array of well-characterized allergens with immunoglobulin E (IgE) binding ability has been described in AD patient disease exacerbations (as well as in patients with cholinergic urticaria), mostly of M. furfur and M. sympodialis, and more recently from M. globosa.125,126 The detection rate of IgE sensitization only to M. sympodialis antigens reaches 60% in severe AD patients.125 Similarly, high sensitization rates of patients with the same diagnosis have been described for M. globosa antigens.127 Possible explanations could include (1) the presence of an undetected persistent population of sensitizing species in skin sanctuaries, like the hair infudibulum, or (2) substantial turn-over in the species that colonize the skin in different life periods thus favoring multiple sensitization events. Additionally, a selectivity of these species for AD cannot be excluded. Thus, in the case of AD the involvement of Malassezia seems to be that of an unavoidable source of constantly synthesized allergens in close vicinity to the susceptive skin within the proposed ‘transitional zone’. The pathophysiological significance of an omnipresent allergen source could be further elaborated in future studies with a focus on allergen expressing behavior of all Malassezia species and also the identification of additional IgE binding Malassezia macromolecules at species and strains level. On the other hand, specific IgE antibodies against Malassezia species are absent to sparse in SD,128 and current data point toward an irritant and/or toxic effect of Malassezia metabolic products on predisposed susceptible skin as the pathophysiologic equivalent. These include lipid hydrolysis products, squalene peroxides, and indolic compounds.119,129,130 Most of these biologically active substances can also be produced by the action of UV light on the skin (e.g., squalene peroxides, L-tryptophan photoproducts), albeit to a lesser degree, a fact that highlights the complexity of the human skin—Malassezia—environmental interactions. The ability to modify the skin levels of these effectors by modulating their synthesis rates in yeast cells is expanded to almost all Malassezia species tested.130,131 Thus, restricting our focus to a particular species would end up with equivocal results. In order to unravel the pathobiology of Malassezia-associated diseases, it is important to comprehend the diversity of the pathogenic pathways that stems from a variety of possible interactions, namely, the higher degree of intraspecies diversity involved, that is, Malassezia species versus human skin, together with the respective metabolic plasticity of a eukaryote. On the other side, the human multicellular host may modify the outcome of this interaction by regulating (1) Malassezia species composition, (2) differential induction of the yeast metabolic pathways, and (3) relevant skin pathogenic pathways. Last but not least, environmental influences that affect both skin and Malassezia yeasts alike, for example, ambient humidity, UV level, and temperature, may lead to perplexing pathophysiologic interactions between human skin and yeasts. Thus elaborate future epidemiological studies, as done by Jo et al.22, could address the first question and guide subsequent Malassezia metabolome experiments to assess the possible roles of proteins, lipids, and bioactive molecules. Therapeutic approaches of Malassezia skin disorders and infections and anti-fungal susceptibility Malassezia are associated with a wide range of superficial diseases and nosocomial infections.6 Despite attempts with topical and systemic antifungals, a trend toward recurrence is often noticed.132,133 Moreover, there has been induction of in vitro fluconazole (FLZ) resistance in M. pachydermatis134,135 as well as treatment failure with terbinafine (TER) in PV patients or with FLZ or posaconazole (POS) in preventative treatment of Malassezia furfur fungemia,26,71,136,137 suggesting occurrence of resistance. Unfortunately, methods for in vitro susceptibility testing for Malassezia spp. have not been standardized,138 and published data describe variable azole susceptibility.136,139–145 Here we summarize data about the therapeutic approaches to Malassezia skin disorders and infections and in vitro antifungal activity of the most commonly employed drugs, that is, azoles, polyenes, allylamines, and echinocandins, against Malassezia yeasts. Therapeutic approaches for Malassezia skin disorders and infections Three classes of antifungals, that is, azoles, polyenes, and echinocandins, are used to manage fungal infections. Azoles and polyenes (amphotericin B, AmB), are frequently employed to treat Malassezia-related skin disorders or infections in humans and animals. For canine Malassezia dermatitis the European Scientific Counsel Companion Animal Parasites (ESCCAP) guideline146 concluded that there was good evidence supporting twice-weekly use of a 2% miconazole / 2% chlorhexidine shampoo. However, the employment of oral ketoconazole (KTZ-10 mg/kg, once daily) and oral itraconazole (ITZ-5 mg/kg, once daily) for 3 weeks was indicated for severe Malassezia-related disorders.133,147 Successive studies confirmed the previous results and indicated the efficacy of pulse administration of 5 mg/kg of ITZ or 30 mg /kg of terbinafine (TER) for at least 3 weeks in the treatment of Malassezia dermatitis in cats and dogs, respectively.148,149 For Malassezia-related human skin disorders, PV and SD patients might be sufficiently treated with topical agents, but maintenance therapy is usually suggested to prevent relapse.26,132,137,150 Even if the evidence for a causal relationship between Malassezia yeasts and atopic dermatitis remains to be better addressed, these yeast species are usually considered the exacerbating factor of atopic dermatitis (AD), and the patients show a good clinical improvement by use of ketoconazole.26 Topical KTZ shampoo (twice weekly) or miconazole cream (twice daily) is useful to treat also PV and SD.132 In particular, treatment of SD was traditionally performed using keratolytic agents or topical corticosteroids.132 However, based on the presumed causative association between Malassezia and SD, the current treatment option is primarily based on topical antifungal agents alone or in combination with corticosteroids.132 For widespread lesions of PV and in cases that are refractory to topical treatment, systemic therapy with FLZ (300 mg/week for 2–3 weeks) or ITZ (200 mg/day for 5 or 7 days up to 3 weeks) may be used.132,137 The effect of these two agents seems to be similar, but FLZ is usually preferred for PV and MF, and ITZ for SD. Oral use of TER seems ineffective in PV, possibly because of a more uneven yeast distribution at the skin surface.26,137,150 Systemic, catheter-related Malassezia infections are usually treated with catheter removal, administration of a systemic antifungal and in some cases by discontinuation of the lipid infusion.138 Intravenous treatment with AmB proved useful in both preterm infants and adults with blood stream infections (Table 2). FLZ, voriconazole (VOR), and posaconazole (POS) may represent alternative options, but clinical evidence suggests failure of these drugs to treat Malassezia fungemia (Table 2). Duration of treatment has not yet been defined, but a course of 14 days of effective antifungal therapy after the last positive blood culture and catheter removal is usually recommended similar to treatment of invasive Candida infections.151 Table 2. Prospective studies on the treatment of Malassezia spp. fungemia reporting clinical and mycological outcome. Species  Agent tested  Protocol  Length of treatment  Hosts  References  Malassezia sympodialis  Amphotericin B deoxycholate  1 mg/kg/day (accumulate dosage 20 mg/kg).  21 days  1 Preterm infant  42  Malassezia pachydermatis + mycobacteria  Liposomal Amphotericin B.+nafcillin  5 mg/kg/day IV  7 days  1 Adult  72  Malassezia pachydermatis  Liposomal Amphotericin B  1 mg/kg/day  NR  1 Adult with oral Posaconazolo prophylaxis  71  Malassezia pachydermatis  Liposomal Amphotericin B  nr  7 days  11 Preterm infant  170  Malassezia pachydermatis  Liposomal Amphotericin B alone or in combination with Flucytosine or Fluconazole  1 mg/kg/day 8 mg/kg/day PO or EV (50–150 mg kg/day PO)  3–5 weeks  8 Preterm neonates  70  Malassezia furfur  Liposomal Amphotericin B  4 mg/kg/day  45 days  1 Preterm infants  171  Malassezia furfur  Liposomal Amphotericin B  From 2.5 to 5 mg/kg  6–20 days  6 preterm infants, 3 with fluconazole prophylaxis  5  Malassezia furfur  Amphotericin B followed by Fluconazole  0.7 mg/ kg/day for10 days; 200 mg daily for 14 days  24 days  1 adult  172  Malassezia furfur  Amphotericin B  1 mg/kg/day  NR  4 adults and 3 children  173  Species  Agent tested  Protocol  Length of treatment  Hosts  References  Malassezia sympodialis  Amphotericin B deoxycholate  1 mg/kg/day (accumulate dosage 20 mg/kg).  21 days  1 Preterm infant  42  Malassezia pachydermatis + mycobacteria  Liposomal Amphotericin B.+nafcillin  5 mg/kg/day IV  7 days  1 Adult  72  Malassezia pachydermatis  Liposomal Amphotericin B  1 mg/kg/day  NR  1 Adult with oral Posaconazolo prophylaxis  71  Malassezia pachydermatis  Liposomal Amphotericin B  nr  7 days  11 Preterm infant  170  Malassezia pachydermatis  Liposomal Amphotericin B alone or in combination with Flucytosine or Fluconazole  1 mg/kg/day 8 mg/kg/day PO or EV (50–150 mg kg/day PO)  3–5 weeks  8 Preterm neonates  70  Malassezia furfur  Liposomal Amphotericin B  4 mg/kg/day  45 days  1 Preterm infants  171  Malassezia furfur  Liposomal Amphotericin B  From 2.5 to 5 mg/kg  6–20 days  6 preterm infants, 3 with fluconazole prophylaxis  5  Malassezia furfur  Amphotericin B followed by Fluconazole  0.7 mg/ kg/day for10 days; 200 mg daily for 14 days  24 days  1 adult  172  Malassezia furfur  Amphotericin B  1 mg/kg/day  NR  4 adults and 3 children  173  Note: NR, not reported. View Large Antimicrobial susceptibility profile of Malassezia species No reference method has been developed, and, hence culture media, inoculum sizes, incubation times, and criteria to determine MIC differ among studies.135,142,143,152 MICs of the most commonly employed drugs to treat dermatitis and/or fungemia are obtained using the modified CLSI broth microdilution test.136,139–145 Regardless of media or other conditions, evidence suggests that antifungal susceptibility profiles against azoles, AMB and TER vary according to species (Table 3). M. sympodialis and M. pachydermatis are the most susceptible, and M. furfur and M. globosa the least susceptible species.136,142,143,152 ITZ and KTZ were the most active for all Malassezia species, and FLZ, VOR, and AmB the least active.136,142,152,153 In particular, wide MIC ranges and higher intra-species variation to FCZ, VOR, and AmB were observed for M. furfur, M. sympodialis, and M. globosa.143,152–154 In addition, the MIC values for FLZ and ITZ of M. furfur isolates obtained from blood stream infected (BSI) patients were usually higher than those isolated from diseased human skin,140–142,144,152,155 suggesting the source of Malassezia might be pivotal in strain susceptibility.140–142,152 The VOR susceptibility is highly variable within M. furfur strains and the MIC values may be higher than those reported for other fungi (i.e., Candida spp. and/or Aspergillus spp.), thus showing a lower efficacy for M. furfur.138,152,155–157 Table 3. Range of MIC values obtained with modified CLSI protocols of Malassezia species from skin lesions and blood stream infections. Malassezia species  Host/lesion  FLZ  KTZ  ITZ  VRZ  POS  TER  AMB  References  Malassezia furfur  Human /SL  ≤0.125>128  ≤0.03–1  ≤0.03–16  ≤0.03–16  0.03-32  0.03-32  0.125 -16  136,140.142–144,152,153  Malassezia furfur  Human /BSI  0.5 > 128  ND  0.03–8  0.06–8  0.016–8  ND  0.25–16  136,152  Malassezia sympodialis  Human /SL  ≤0.125–16  0.015–4  ≤0.03–1  0.015–1  0.03-0.6  0.05–0.8  0.125–4  140,143,144,153  Malassezia globosa  Human /SL  ≤0.125–32  0.015––8  0.015––8  0.03–>8  0.03–0.06  0.03–16  0.1–4  140,143,144,153  Malassezia pachydermatis  Dogs /SL  1–>64  <0.008–4  0.03-4  0.06–8  0.008–4  0.063–2  0.06–0.5  135,140–142,144–145  Malassezia species  Host/lesion  FLZ  KTZ  ITZ  VRZ  POS  TER  AMB  References  Malassezia furfur  Human /SL  ≤0.125>128  ≤0.03–1  ≤0.03–16  ≤0.03–16  0.03-32  0.03-32  0.125 -16  136,140.142–144,152,153  Malassezia furfur  Human /BSI  0.5 > 128  ND  0.03–8  0.06–8  0.016–8  ND  0.25–16  136,152  Malassezia sympodialis  Human /SL  ≤0.125–16  0.015–4  ≤0.03–1  0.015–1  0.03-0.6  0.05–0.8  0.125–4  140,143,144,153  Malassezia globosa  Human /SL  ≤0.125–32  0.015––8  0.015––8  0.03–>8  0.03–0.06  0.03–16  0.1–4  140,143,144,153  Malassezia pachydermatis  Dogs /SL  1–>64  <0.008–4  0.03-4  0.06–8  0.008–4  0.063–2  0.06–0.5  135,140–142,144–145  Note: AmB, amphotericin B; BSI, blood stream infection; FLZ, fluconazole; ITZ, itraconazole; KTZ, ketoconazole; POS, posaconazole; SL, skin lesion; TER, terbinafine. View Large AMB is very active against M. pachydermatis158 but less so against M. furfur strains causing fungemia,153,159 which is linked to the AMB formulations.159 MICs of M. furfur were lower when liposomal AMB (l-AmB) was used, which may be due to the lipophilic nature of this yeast species.159 A higher efficacy of AmB (both l-AmB and AmB deoxycholate) was recorded for M. furfur strains coming from patients retreated with FLC, most likely due the synergic effect of azoles with AMB. This confirms that the combination of FLC plus AMB might be more effective toward a more rapid clearance of the BSI.152 The variations in susceptibility among Malassezia species to TER were greater compared to those obtained with the azole drugs (KTZ, ITZ, VOR, Table 2). M. furfur is less susceptible to TER than M. sympodialis and M. pachydermatis.144,145,153 For echinocandins limited data exist and the MIC values for M. furfur,160 that is, MIC >64 mg/l, need to be confirmed as Malassezia yeasts species are considered intrinsically resistant to these drugs as reported for other basidiomycetes fungi.138,161 Clinical outcome and in vitro susceptibility of Malassezia species The correlation of antifungal susceptibility with clinical outcome has been rarely reported and deserves further investigation. Preliminary results showed that FLZ high MIC values (i.e., >64 mg/l), correlated well with poor clinical response. Indeed, it has been shown that M. furfur strains originating from human patients receiving FLC prophylaxis (3 mg/Kg), but developing M. furfur BSI, presented high MIC values (i.e., >128),136 regardless of the media employed for testing in vitro susceptibility.136 On the contrary, high AmB MIC values were detected in M. furfur strains coming from patients with a positive clinical outcome with AmB therapy alone,159 thus suggesting the unsuitability of the methods, that is, media used, reading time as well inoculum concentration, employed to test the in vitro susceptibility.159 However, since similar results for the same Malassezia species (i.e., AmB MICs of M. furfur >2 mg/l) were obtained by other authors applying different methods,143,144 the high MIC values may be real and the positive outcome of patients might be due to the synergic effect of additional drugs.159 Indeed lower AMB MIC values were registered for M. furfur strains coming from BSI patients receiving FLC prophylaxis and treated with AMB, than those coming from patients treated with AMB alone.136,159 In addition, the high in vitro activity of AmB against M. pachydermatis using the same methodology suggests that the low M. furfur AmB susceptibility may be species dependent. Variations in quantity or type of sterols in cell membranes, as well as the inhibition of oxidative action of AmB due to high activity of fungal intracellular catalase and/or superoxide dismutase, may contribute to the low susceptibility of M. furfur to AMB.136,143,144 However, the observed incongruences between clinical outcome and in vitro-obtained susceptibility results need further investigation. Future, collaborative studies and clinical trials are essential for correlating in vitro results with clinical outcomes, but the data presented herein suggest that the high MICs of FLZ and VOR for Malassezia species indicate that they are not a good treatment option. The high susceptibility for AMB in M. furfur from BSI patients receiving FLC prophylaxis might indicate that AmB treatment should be combined with FLZ for a better prognosis. Guidelines for the treatment of Malassezia skin disorders have been assessed both for pet animals and humans, but those related to systemic mycoses are not available to date.138 Clinical evidence indicated the efficacy of azole drugs for the control of the skin disorders and of AmB for systemic infections.138 However, the common recurrence of skin disorders as well as the severity of infections suggests the use of high doses of antifungal agents for prolonged time periods.132,133,137,146 The observed high inter- and intra-species differences of Malassezia antifungal profiles may explain the differences observed in mycological cure rates when an antifungal agent is used to treat what appears to be clinically the same disease state. This can be due to different Malassezia species being involved in the same clinical presentation, and/or different genetic types of Malassezia species with different antifungal profile may colonize the same host.6,162 Despite the variable MIC data according to the protocol used, evidence exists that these yeasts have a low susceptibility to FLZ and VOR. In addition, the recent finding that efflux pump inhibitors, such as haloperidol (HAL) and pro-methazine (PTZ), display a synergistic interaction with FLZ and/or VOR only in Malassezia strains with high azole MIC values (i.e., FLZ MIC ≥ 128 μg/ml for M. furfur, FLZ MIC ≥ 64 μg/ml for M. pachydermatis and VOR MIC ≥ 4 μg/ml in both Malassezia spp.) suggests that the efflux pump genes might be overexpressed in the above strains, eventually resulting in azole resistance phenomena.163 Also the biofilm formation previously demonstrated for both M. pachydermatis and M. furfur might contribute to the low azole susceptibilities of these yeast species.164,165 The in vivo efficacy of these antifungal agents needs to be further evaluated by assessing the correlation between MICs and clinical outcomes. Only two studies reported high MIC values for azoles, that is, FLZ and POS, with unsuccessful treatment and/or prophylaxis,71,136 but these results need to be validated in multicentre studies in order to promptly develop therapeutic guidelines. Discussion The genus Malassezia comprises a heterogeneous group of species, and several species comprise multiple genotypes. These species/genotypes are specifically associated with mammalian hosts, but by using culture-independent techniques they were also retrieved from much wider-spread habitats, including various terrestrial and marine ecosystems and even deep-sea sediments. To date most studies dealing with the ecology and clinical occurrence of Malassezia are culture-based and provide us with strains suitable for genetic and phenotypic studies. On the other hand, culture-based methods have limitations and may not accurately represent the role of Malassezia species in the microbiome, ecology, or pathology due to their slow and fastidious growth and the fact that culturing conditions may not accurately represent the complexity of the natural habitat. Only in recent years, culture-independent approaches have been applied, adding valuable insights to the presence, abundance and the role of Malassezia spp. in various ecosystems. In order to understand the full potential of these new non–culture-based approaches it is important to be aware of their limitations and challenges. In general, with modern and sensitive community-analysis approaches, methodology variation has a huge impact, stressing the need for method standardization to allow meaningful future comparisons. Body sites vary in their physical and physiological composition166 potentially requiring unique sampling approaches to accurately collect microbial communities. Malassezia species have a rigorous cell wall, thus requiring a more stringent DNA-extraction method when compared to many other microorganisms. Other important downstream variables are PCR-primer design and (genome) sequence data availability. Finally, inclusion of proper controls is needed to correct for potential contamination, including fungal DNA-contamination of commercially available PCR reagents.167 Twenty years after the first landmark elucidation of the species status in Malassezia,29 a still pending question is whether the diversity found on human skin reflects on pathophysiologic associations of so-called pathogenic species with all or any of the different Malassezia-related disorders PV, D/SD, and AD. We suggest that the delineation of this question does not lay on the identification of culprit pathogenic species, but rather on the characterization of the metabolic impact of mixed Malassezia skin communities comprising the many genotypes that colonize each individual. The application of recently developed gene-deletion tools and model systems addressing different levels of immunological status will be necessary to study the role of specific genes in the pathogenesis of Malassezia. Now that transformation and genetic engineering of Malassezia has been made possible,117,168 it is likely that the roles of these and other genes and pathways in pathogenicity will be clarified. For the moment, it is important to be aware that the genus Malassezia comprises a heterogeneous group of species consisting of different genotypes that might cause the same pathologies. Moreover, these species and genotypes may vary in their susceptibility to different antifungal agents. In particular, the low susceptibility to FLZ or VOR should be considered when a long term or prophylactic therapy is implemented. Since maintenance therapy is essential for the successful management of relapsing skin disorders and infections, studies on alternative drugs should be encouraged. Whole-genome sequencing of Malassezia biodiversity enabling detailed analysis of the biochemical mechanisms involved in the adaptation to skin may pave the road to future therapeutic drug design. Declaration of Interest G.G., D.B. have received Research Grants to perform relevant work by Johnson and Johnson, Procter & Gamble and L’Oreal. T.D. is a former employee of the Procter & Gamble Co. The authors are responsible for the content and the writing of the paper. References 1. Gemmer CM, DeAngelis YM, Theelen B, Boekhout T, Dawson TL. Fast, noninvasive method for molecular detection and differentiation of Malassezia yeast species on human skin and application of the method to dandruff microbiology. J Clin Microbiol . 2002; 40: 3350– 3357. Google Scholar CrossRef Search ADS PubMed  2. Findley K, Oh J, Yang J et al.   Topographic diversity of fungal and bacterial communities in human skin. Nature . 2013; 498: 367– 370. Google Scholar CrossRef Search ADS PubMed  3. Oh J, Byrd AL, Deming C et al.   Biogeography and individuality shape function in the human skin metagenome. Nature . 2014; 514: 59– 64. Google Scholar CrossRef Search ADS PubMed  4. Prohic A, Jovovic Sadikovic T, Krupalija-Fazlic M, Kuskunovic-Vlahovljak S. Malassezia species in healthy skin and in dermatological conditions. Int J Dermatol . 2016; 55: 494– 504. Google Scholar CrossRef Search ADS PubMed  5. Iatta R, Cafarchia C, Cuna T et al.   Bloodstream infections by Malassezia and Candida species in critical care patients. Med Mycol . 2014; 52: 264– 269. Google Scholar CrossRef Search ADS PubMed  6. Velegraki A, Cafarchia C, Gaitanis G, Iatta R, Boekhout T. Malassezia infections in humans and animals: pathophysiology, detection, and treatment. PLoS Pathog . 2015; 11: e1004523. Google Scholar CrossRef Search ADS PubMed  7. Wang QM, Theelen B, Groenewald M, Bai FY, Boekhout T. Moniliellomycetes and Malasseziomycetes, two new classes in Ustilaginomycotina. Persoonia . 2014; 33: 41– 47. Google Scholar CrossRef Search ADS PubMed  8. Wu G, Zhao H, Li C et al.   Genus-wide comparative genomics of Malassezia delineates its phylogeny, physiology, and niche adaptation on human skin. PLoS Genet . 2015; 11 e1005614. Google Scholar CrossRef Search ADS PubMed  9. Boekhout T, Mayser P, Guého-Kellermann E, Velegraki A, eds. Malassezia and the Skin , 1st edn. Berlin: Springer; 2010. Google Scholar CrossRef Search ADS   10. Castellá G, Coutinho SDA, Cabañes FJ. Phylogenetic relationships of Malassezia species based on multilocus sequence analysis. Med Mycol . 2014; 52: 99– 105. Google Scholar PubMed  11. Cabanes FJ, Acqua SD, Puig L, Bragulat MR, Castellá G. New lipid-dependent Malassezia species from parrots. Rev Iberoam Micol . 2016; 33: 92– 99. Google Scholar CrossRef Search ADS PubMed  12. Honnavar P, Prasad GS, Ghosh A, Dogra S, Handa S, Rudramurthy SM. Malassezia arunalokei sp. nov., a novel yeast species isolated from seborrhoeic dermatitis patients and healthy individuals from India. J Clin Microbiol . 2016; 54: 1826– 1834 Google Scholar CrossRef Search ADS PubMed  13. Gupta AK. Molecular identification of Malassezia species by amplified fragment length polymorphism (AFLP) and sequence analyses of the internal transcribed spacer (ITS) and large subunit (LSU) regions of ribosomal DNA. J Am Acad Dermatol . 2004; 50: 106. Google Scholar CrossRef Search ADS   14. Cafarchia C, Gasser RB, Figueredo LA, Latrofa MS, Otranto D. Advances in the identification of Malassezia. Mol Cell Probes.  2011; 25: 1– 7. Google Scholar CrossRef Search ADS PubMed  15. Kolecka A, Khayhan K, Arabatzis M et al.   Efficient identification of Malassezia yeasts by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Br J Dermatol . 2014; 170: 332– 341. Google Scholar CrossRef Search ADS PubMed  16. Ilahi A, Hadrich I, Neji S, Trabelsi H, Makni F, Ayadi A. Real-Time PCR identification of six Malassezia species. Curr Microbiol . 2017; 74: 671– 677. Google Scholar CrossRef Search ADS PubMed  17. Vuran E, Karaarslan A, Karasartova D, Turegun B, Sahin F. Identification of Malassezia species from pityriasis versicolor lesions with a new multiplex PCR Method. Mycopathologia . 2014; 177: 41– 49. Google Scholar CrossRef Search ADS PubMed  18. Denis J, Machouart M, Morio F et al.   Performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identifying clinical Malassezia Isolates. J Clin Microbiol . 2017; 55: 90– 96. Google Scholar CrossRef Search ADS PubMed  19. Leung MHY, Chan KCK, Lee PKH. Skin fungal community and its correlation with bacterial community of urban Chinese individuals. Microbiome . 2016; 4: 46. Google Scholar CrossRef Search ADS PubMed  20. Akaza N, Akamatsu H, Sasaki Y et al.   Cutaneous Malassezia microbiota of healthy subjects differ by sex, body part and season. J Dermatol . 2010; 37: 786– 792. Google Scholar CrossRef Search ADS PubMed  21. Nagata R, Nagano H, Ogishima D, Nakamura Y, Hiruma M, Sugita T. Transmission of the major skin microbiota, Malassezia, from mother to neonate. Pediatr Int . 2012; 54: 350– 355. Google Scholar CrossRef Search ADS PubMed  22. Jo JH, Deming C, Kennedy EA et al.   Diverse human skin fungal communities in children converge in adulthood. J Invest Dermatol . 2016; 136: 2356– 2363. Google Scholar CrossRef Search ADS PubMed  23. Findley K, Grice EA. The skin microbiome: a focus on pathogens and their association with skin disease. PLoS Pathog . 2014; 10: e1004436. Google Scholar CrossRef Search ADS PubMed  24. Sugita T, Yamazaki T, Yamada S et al.   Temporal changes in the skin Malassezia microbiota of members of the Japanese Antarctic Research Expedition (JARE): A case study in Antarctica as a pseudo-space environment. Med Mycol . 2015; 53: 717– 724. Google Scholar CrossRef Search ADS PubMed  25. Sugita T, Yamazaki T, Makimura K et al.   Comprehensive analysis of the skin fungal microbiota of astronauts during a half-year stay at the International Space Station. Med Mycol . 2016; 54: 232– 239. Google Scholar CrossRef Search ADS PubMed  26. Gupta AK, Batra R, Bluhm R, Boekhout T, Dawson TL. Skin diseases associated with Malassezia species. J Am Acad Dermatol . 2004; 51: 785– 798. Google Scholar CrossRef Search ADS PubMed  27. Guého-Kellermann E, Boekhout T, Begerow D. Malassezia and the skin: science and clinical practice. In: Boekhout T, Mayser P, Guého-Kellermann E, Velegraki A, eds. Malassezia and the Skin , 1st edn. Berlin: Springer; 2010: 17– 63. 28. Tanaka A, Cho O, Saito M, Tsubol R, Kurakado S, Sugita T. Molecular characterization of the skin fungal microbiota in patients with seborrheic dermatitis. J Clin Exp Dermatol Res . 2014; 5: 5– 8. 29. Guého E, Midgley G, Guillot J. The genus Malassezia with description of four new species. Antonie Van Leeuwenhoek . 1996; 69: 337– 355. Google Scholar CrossRef Search ADS PubMed  30. Crespo-Erchiga V, Florencio VD. Malassezia yeasts and pityriasis versicolor. Curr Opin Infect Dis . 2006; 19: 139– 147. Google Scholar CrossRef Search ADS PubMed  31. Aspiroz C, Moreno LA, Rezusta A, Rubio C. Differentiation of three biotypes of Malassezia species on human normal skin.: correspondence with M. globosa, M. sympodialis and M. restricta. Mycopathologia . 1999; 145: 69– 74. Google Scholar CrossRef Search ADS PubMed  32. Nakabayashi A, Sei Y, Guillot J. Identification of Malassezia species isolated from patients with seborrhoeic dermatitis, atopic dermatitis, pityriasis versicolor and normal subjects. Med Mycol . 2000; 38: 337– 341. Google Scholar CrossRef Search ADS PubMed  33. Gaitanis G, Velegraki A, Alexopoulos EC, Chasapi V, Tsigonia A, Katsambas A. Distribution of Malassezia species in pityriasis versicolor and seborrhoeic dermatitis in Greece: typing of the major pityriasis versicolor isolate M. globosa. Br J Dermatol . 2006; 154: 854– 859 Google Scholar CrossRef Search ADS PubMed  34. Gupta AK, Kohli Y, Summerbell RC, Faergemann J. Quantitative culture of Malassezia species from different body sites of individuals with or without dermatoses. Med Mycol . 2001; 39: 243– 251. Google Scholar CrossRef Search ADS PubMed  35. Batra R, Boekhout T, Guého E, Cabañes FJ, Dawson TL, Gupta AK. Malassezia Baillon, emerging clinical yeasts. FEMS Yeast Res . 2005; 5: 1101– 1113. Google Scholar CrossRef Search ADS PubMed  36. Sugita T, Tajima M, Tsubuku H, Tsuboi R, Nishikawa A. Quantitative analysis of cutaneous Malassezia in atopic dermatitis patients using real-time PCR. Microbiol Immunol . 2006; 50: 549– 552. Google Scholar CrossRef Search ADS PubMed  37. Clavaud C, Jourdain R, Bar-Hen A et al.   Dandruff Is associated with disequilibrium in the proportion of the major bacterial and fungal populations colonizing the scalp. PLoS One . 2013; 8: e58203 Google Scholar CrossRef Search ADS PubMed  38. Simmons RB, Gueho E. A new species of Malassezia. Mycol Res . 1990; 94: 1146– 1149. Google Scholar CrossRef Search ADS   39. Guillot J, Guého E. The diversity of Malassezia yeasts confirmed by rRNA sequence and nuclear DNA comparisons. Antonie Van Leeuwenhoek . 1995; 67: 297– 314. Google Scholar CrossRef Search ADS PubMed  40. Bond R, Howell SA, Haywood PJ, Lloyd DH. Isolation of Malassezia sympodialis and Malassezia globosa from healthy pet cats. Vet Rec . 1997; 141: 200– 201. Google Scholar CrossRef Search ADS PubMed  41. Crespo Erchiga V, Ojeda Martos AA, Vera Casaño A, Crespo Erchiga A, Sánchez Fajardo F. Isolation and identification of Malassezia spp. In pytiriasis versicolor, seborrheic dermatitis and healthy skin. Rev Iberoam Micol . 1999; 16: S16– 21. Google Scholar PubMed  42. Aguirre C, Euliarte C, Finquelievich J, Sosa M de los Á, Giusiano G. Fungemia and interstitial lung compromise caused by Malassezia sympodialis in a pediatric patient. Rev Iberoam Micol . 2015; 32: 118– 121. Google Scholar CrossRef Search ADS PubMed  43. Patron RL. A 34-year-old man with cough, lung nodules, fever, and eosinophilia. Clin Infect Dis . 2016; 63: 1525– 1526 Google Scholar CrossRef Search ADS PubMed  44. Cabañes FJ, Theelen B, Castellá G, Boekhout T. Two new lipid-dependent Malassezia species from domestic animals. FEMS Yeast Res . 2007; 7: 1064– 1076. Google Scholar CrossRef Search ADS PubMed  45. Sugita T, Takashima M, Shinoda T et al.   New yeast species, Malassezia dermatis, isolated from patients with atopic dermatitis. 2002; 40: 1363– 1367. 46. Brooks R, Brown L. Systemic infection with Malassezia furfur in an adult receiving long-term hyperalimentation therapy. J Infect Dis . 1987; 156: 410– 411. Google Scholar CrossRef Search ADS PubMed  47. Dankner WM, Spector SA, Fierer J, Davis CE. Malassezia fungemia in neonates and adults: complication of hyperalimentation. Rev Infect Dis . 1987; 9: 743– 753. Google Scholar CrossRef Search ADS PubMed  48. Richet HM, McNeil MM, Edwards MC, Jarvis WR. Cluster of Malassezia furfur pulmonary infections in infants in a neonatal intensive-care unit. J Clin Microbiol . 1989; 27: 1197– 1200. Google Scholar PubMed  49. Surmont I, Gavilanes A, Vandepitte J, Devlieger H, Eggermont E. Malassezia furfur fungaemia in infants receiving intravenous lipid emulsions: a rarity or just underestimated? Eur J Pediatr . 1989; 148: 435– 438. Google Scholar CrossRef Search ADS PubMed  50. Weiss SJ, Schoch PE, Cunha BA. Malassezia furfur fungemia associated with central venous catheter lipid emulsion infusion. Heart Lung . 1991; 20: 87– 90. Google Scholar PubMed  51. Boekhout T, Bosboom RW. Karyotyping of Malassezia yeasts: taxonomic and epidemiological implications. Syst Appl Microbiol . 1994; 17: 146– 153. Google Scholar CrossRef Search ADS   52. Kaneko T, Murotani M, Ohkusu K, Sugita T, Makimura K. Genetic and biological features of catheter-associated Malassezia furfur from hospitalized adults. Med Mycol . 2012; 50: 74– 80. Google Scholar CrossRef Search ADS PubMed  53. Bell LM, Alpert G, Slight PH et al.   Malassezia furfur Skin colonization in infancy. Infect Control Hosp Epidemiol . 1988; 9: 151– 153. Google Scholar CrossRef Search ADS PubMed  54. Gupta P, Chakrabarti A, Singhi S, Kumar P, Honnavar P, Rudramurthy SM. Skin colonization by Malassezia spp. in hospitalized neonates and infants in a tertiary care centre in North India. Mycopathologia . 2014; 178: 267– 272. Google Scholar CrossRef Search ADS PubMed  55. Theelen B, Silvestri M, Guého E, van Belkum A, Boekhout T. Identification and typing of Malassezia yeasts using amplified fragment length polymorphism (AFLP), random amplified polymorphic DNA (RAPD) and denaturing gradient gel electrophoresis (DGGE). FEMS Yeast Res . 2001; 1: 79– 86. Google Scholar CrossRef Search ADS PubMed  56. Gupta AK, Boekhout T, Theelen B, Summerbell R, Batra R. Identification and typing of Malassezia species by amplified fragment length polymorphism and sequence analyses of the internal transcribed spacer and large-subunit regions of ribosomal DNA. J Clin Microbiol . 2004; 42: 4253– 4260. Google Scholar CrossRef Search ADS PubMed  57. Sugita T, Takashima M, Kodama M, Tsuboi R, Nishikawa A. Description of a new yeast species, Malassezia japonica, and its detection in patients with atopic dermatitis and healthy subjects. Society . 2003; 41: 4695– 4699. 58. Crespo MJ, Abarca ML, Cabañes FJ. Atypical lipid-dependent Malassezia species isolated from dogs with otitis externa. J Clin Microbiol . 2000; 38: 2383– 2385. Google Scholar PubMed  59. Crespo MJ, Abarca ML, Cabañes FJ. Occurrence of Malassezia spp. in the external ear canals of dogs and cats with and without otitis externa. Med Mycol . 2002; 40: 115– 121. Google Scholar CrossRef Search ADS PubMed  60. Jung WH, Croll D, Cho JH, Kim YR, Lee YW. Analysis of the nasal vestibule mycobiome in patients with allergic rhinitis. Mycoses . 2015; 58: 167– 172. Google Scholar CrossRef Search ADS PubMed  61. Sugita T, Tajima M, Takashima M et al.   A new yeast, Malassezia yamatoensis, isolated from a patient with seborrheic dermatitis, and its distribution in patients and healthy subjects. Microbiol Immunol . 2004; 48: 579– 583. Google Scholar CrossRef Search ADS PubMed  62. van Woerden HC, Gregory C, Brown R, Marchesi JR, Hoogendoorn B, Matthews IP. Differences in fungi present in induced sputum samples from asthma patients and non-atopic controls: a community based case control study. BMC Infect Dis . 2013; 13: 69. Google Scholar CrossRef Search ADS PubMed  63. Gueho E, Simmons RB, Pruitt WR, Meyer SA, Ahearn DG. Association of Malassezia pachydermatis with systemic infections of humans. J Clin Microbiol . 1987; 25: 1789– 1790. Google Scholar PubMed  64. Larocco M, Dorenbaum A, Robinson A, Pickering LK. Recovery of Malassezia pachydermatis from eight infants in a neonatal intensive care nursery: clinical and laboratory features. Pediatr Infect Dis J . 1988; 7: 398– 401. Google Scholar CrossRef Search ADS PubMed  65. Mickelsen PA, Viano-Paulson MC, Stevens DA, Diaz PS. Clinical and microbiological features of infection with Malassezia pachydermatis in high-risk infants. J Infect Dis . 1988; 157: 1163– 1168. Google Scholar CrossRef Search ADS PubMed  66. van Belkum A Boekhout T, Bosboom R. Monitoring spread of Malassezia infections in a neonatal intensive care unit by PCR-mediated genetic typing. J Clin Microbiol . 1994; 32: 2528– 2532. Google Scholar PubMed  67. Guého E, Boekhout T, Ashbee HR, Guillot J, Van Belkum A, Faergemann J. The role of Malassezia species in the ecology of human skin and as pathogens. Med Mycol . 1998; 36: 220– 229. Google Scholar PubMed  68. Chang HJ, Miller HL, Watkins N et al.   An epidemic of Malassezia pachydermatis in an intensive care nursery associated with colonization of health care workers’ pet dogs. N Engl J Med . 1998; 338: 706– 711. Google Scholar CrossRef Search ADS PubMed  69. Lautenbach E, Nachamkin I, Schuster MG. Malassezia pachydermatis infections. N Engl J Med . 1998; 339: 270. Google Scholar CrossRef Search ADS PubMed  70. Chryssanthou E, Broberger U, Petrini B. Malassezia pachydermatis fungaemia in a neonatal intensive care unit. Acta Paediatr . 2001; 90: 323– 327. Google Scholar CrossRef Search ADS PubMed  71. Choudhury S, Marte RL. Malassezia pachydermatis fungaemia in an adult on posaconazole prophylaxis for acute myeloid leukaemia. Pathology . 2014; 46: 466– 467. Google Scholar CrossRef Search ADS PubMed  72. Roman J, Bagla P, Ren P, Blanton LS, Berman MA. Malassezia pachydermatis fungemia in an adult with multibacillary leprosy. Med Mycol Case Rep . 2016; 12: 1– 3. Google Scholar CrossRef Search ADS PubMed  73. Prohic A, Kasumagic-Halilovic E. Identification of Malassezia pachydermatis from healthy and diseased human skin. Med Arh . 2009; 63: 317– 319. Google Scholar PubMed  74. Morris DO, O’Shea K, Shofer FS, Rankin S. Malassezia pachydermatis carriage in dog owners. Emerg Infect Dis . 2005; 11: 83– 88. Google Scholar CrossRef Search ADS PubMed  75. Gaitanis G, Magiatis P, Stathopoulou K et al.   AhR ligands, malassezin, and indolo[3,2-b]carbazole are selectively produced by Malassezia furfur strains isolated from seborrheic dermatitis. J Invest Dermatol . 2008; 128: 1620– 1625. Google Scholar CrossRef Search ADS PubMed  76. Gaitanis G, Velegraki A, Magiatis P, Pappas P, Bassukas ID. Could Malassezia yeasts be implicated in skin carcinogenesis through the production of aryl-hydrocarbon receptor ligands? Med Hypotheses . 2011; 77: 47– 51. Google Scholar CrossRef Search ADS PubMed  77. Chng KR, Tay ASL, Li C et al.   Whole metagenome profiling reveals skin microbiome-dependent susceptibility to atopic dermatitis flare. Nat Microbiol . 2016; 1: 16106. Google Scholar CrossRef Search ADS PubMed  78. Cleland EJ, Bassiouni A, Boase S, Dowd S, Vreugde S, Womald PJ. The fungal microbiome in chronic rhinosinusitis: richness, diversity, postoperative changes and patient outcomes. Int Forum Allergy Rhinol . 2014; 4: 259– 265. Google Scholar CrossRef Search ADS PubMed  79. Gelber JT, Cope EK, Goldberg AN, Pletcher SD. Evaluation of Malassezia and Common Fungal Pathogens in Subtypes of Chronic Rhinosinusitis. Int Forum Allergy Rhinol . 2016; 6: 950– 955. Google Scholar CrossRef Search ADS PubMed  80. Dupuy AK, David MS, Li L et al.   Redefining the human oral mycobiome with improved practices in amplicon-based taxonomy: discovery of Malassezia as a prominent commensal. PLoS One . 2014; 9: e90899. Google Scholar CrossRef Search ADS PubMed  81. Ghannoum MA, Jurevic RJ, Mukherjee PK et al.   Characterization of the oral fungal microbiome (mycobiome) in healthy individuals. PLoS Pathog . 2010; 6: e1000713. Google Scholar CrossRef Search ADS PubMed  82. Diaz PI, Hong B-Y, Dupuy AK, Strausbaugh LD. Mining the oral mycobiome: Methods, components, and meaning. Virulence . 2017; 8: 313– 323. Google Scholar CrossRef Search ADS PubMed  83. Shelburne SA, Ajami NJ, Chibucos MC et al.   Implementation of a pan-genomic approach to investigate holobiont-infecting microbe interaction: a case report of a leukemic patient with invasive mucormycosis. PLoS One . 2015; 10: e0139851. Google Scholar CrossRef Search ADS PubMed  84. Persoon IF, Buijs MJ, Özok AR et al.   The mycobiome of root canal infections is correlated to the bacteriome. Clin Oral Investig . 2017; 21: 1871– 1881. Google Scholar CrossRef Search ADS PubMed  85. Delhaes L, Monchy S, Fréalle E et al.   The airway microbiota in cystic fibrosis: a complex fungal and bacterial community—implications for therapeutic management. PLoS One . 2012; 7: e36313. Google Scholar CrossRef Search ADS PubMed  86. Willger SD, Grim SL, Dolben EL et al.   Characterization and quantification of the fungal microbiome in serial samples from individuals with cystic fibrosis. Microbiome . 2014; 2: 40. Google Scholar CrossRef Search ADS PubMed  87. Gouba N, Raoult D, Drancourt M. Eukaryote culturomics of the gut reveals new species. PLoS One . 2014; 9: e106994. Google Scholar CrossRef Search ADS PubMed  88. Suhr MJ, Hallen-Adams HE. The human gut mycobiome: pitfalls and potentials-a mycologist's perspective. Mycologia . 2015; 107: 1057– 1073. Google Scholar CrossRef Search ADS PubMed  89. Strati F, Di Paola M, Stefanini I et al.   Age and gender affect the composition of fungal population of the human gastrointestinal tract. Front Microbiol . 2016; 7: 1227. Google Scholar CrossRef Search ADS PubMed  90. Hallen-Adams HE, Suhr MJ. Fungi in the healthy human gastrointestinal tract. Virulence . 2017; 8: 352– 358. Google Scholar CrossRef Search ADS PubMed  91. Bond R. Superficial veterinary mycoses. Clin Dermatol . 2010; 28: 226– 236. Google Scholar CrossRef Search ADS PubMed  92. Sugita T, Boekhout T, Velegraki A, Guillot J, Hađina S, Cabañes FJ. Epidemiology of Malassezia-related skin infections. In: Boekhout T, Mayser P, Guého-Kellermann E, Velegraki A, eds. Malassezia and the Skin , 1st edn. Berlin: Springer; 2010: 65– 119. 93. Cabañes FJ. Malassezia yeasts: how many species infect humans and animals? PLoS Pathog . 2014; 10: e1003892. Google Scholar CrossRef Search ADS PubMed  94. Guillot J, Guého E, Chévrier G, Chermette R. Epidemiological analysis of Malassezia pachydermatis isolates by partial sequencing of the large subunit ribosomal RNA. Res Vet Sci . 1997; 62: 22– 25. Google Scholar CrossRef Search ADS PubMed  95. Puig L, Castellá G, Cabañes FJ. Cryptic diversity of Malassezia pachydermatis from healthy and diseased domestic animals. Mycopathologia . 2016; 181: 681– 688. Google Scholar CrossRef Search ADS PubMed  96. Shokri H, Khosravi AR. An epidemiological study of animals dermatomycoses in Iran. J Mycol Med . 2016; 26: 170– 177. Google Scholar CrossRef Search ADS PubMed  97. Hirai A, Kano R, Makimura K et al.   Malassezia nana sp. nov., a novel lipid-dependent yeast species isolated from animals. Int J Syst Evol Microbiol . 2004; 54: 623– 627. Google Scholar CrossRef Search ADS PubMed  98. Castellá G, De Bellis F Bond R, Cabañes FJ. Molecular characterization of Malassezia nana isolates from cats. Vet Microbiol . 2011; 148: 363– 367. Google Scholar CrossRef Search ADS PubMed  99. Aldrovandi AL, Osugui L, Acqua Coutinho SD. Is Malassezia nana the main species in horses’ ear canal microbiome? Braz J Microbiol . 2016; 47: 770– 774. Google Scholar CrossRef Search ADS PubMed  100. Duarte ER, Batista RD, Hahn RC, Hamdan JS. Factors associated with the prevalence of Malassezia species in the external ears of cattle from the state of Minas Gerais, Brazil. Med Mycol . 2003; 41: 137– 142. Google Scholar PubMed  101. Shokri H. Occurrence and distribution of Malassezia species on skin and external ear canal of horses. Mycoses . 2016; 59: 28– 33. Google Scholar CrossRef Search ADS PubMed  102. Richards TA, Jones MDM, Leonard G, Bass D. Marine fungi: their ecology and molecular diversity. Ann Rev Mar Sci . 2012; 4: 495– 522. Google Scholar CrossRef Search ADS PubMed  103. Amend A. From dandruff to deep-sea vents: Malassezia-like fungi are ecologically hyper-diverse. PLoS Pathog . 2014; 10: e1004277. Google Scholar CrossRef Search ADS PubMed  104. Elhady A, Giné A, Topalovic O et al.   Microbiomes associated with infective stages of root-knot and lesion nematodes in soil. PLoS One . 2017; 12: e0177145. Google Scholar CrossRef Search ADS PubMed  105. Quandt A, Glasco A, James T. Intestinal mycobiome variation across geography and phylogeny in the snail genus Conus. In: 29th Fungal Genetics Conference Asilomar . Vol Asilomar: Genetics Society of America; 2017: 20. 106. Renker C, Alphei J, Buscot F. Soil nematodes associated with the mammal pathogenic fungal genus Malassezia (Basidiomycota: Ustilaginomycetes) in Central European forests. Biol Fertil Soils . 2003; 37: 70– 72. 107. Duarte ER, Resende JC, Rosa CA, Hamdan JS. Prevalence of yeasts and mycelial fungi in bovine parasitic otitis in the state of Minas Gerais, Brazil. J Vet Med B Infect Dis Vet Public Health . 2001; 48: 631– 635. Google Scholar CrossRef Search ADS PubMed  108. Malacrinò A, Schena L, Campolo O et al.   A metabarcoding survey on the fungal microbiota associated to the olive fruit fly. Microb Ecol . 2017; 73: 677– 684. Google Scholar CrossRef Search ADS PubMed  109. Zhu Y, Engström PG, Tellgren-Roth C et al.   Proteogenomics produces comprehensive and highly accurate protein-coding gene annotation in a complete genome assembly of Malassezia sympodialis. Nucleic Acids Res . 2017; 45: 2629– 2643 Google Scholar PubMed  110. Triana S, Ohm RA, De Cock H, Restrepo S, Celis A. Draft genome sequence of the animal and human pathogen Malassezia pachydermatis strain CBS 1879. Genome Announc . 2015; 3: 5– 6. Google Scholar CrossRef Search ADS   111. Xu J, Saunders CW, Hu P et al.   Dandruff-associated Malassezia genomes reveal convergent and divergent virulence traits shared with plant and human fungal pathogens. Proc Natl Acad Sci U S A . 2007; 104: 18730– 18735. Google Scholar CrossRef Search ADS PubMed  112. Saunders CW, Scheynius A, Heitman J. Malassezia fungi are specialized to live on skin and associated with dandruff, eczema, and other skin diseases. PLoS Pathog . 2012; 8: e1002701. Google Scholar CrossRef Search ADS PubMed  113. Gordon James A, Abraham KH, Cox DS, Moore AE, Pople JE. Metabolic analysis of the cutaneous fungi Malassezia globosa and M. restricta for insights on scalp condition and dandruff. Int J Cosmet Sci . 2013; 35: 169– 175. Google Scholar CrossRef Search ADS PubMed  114. Wisecaver JH, Alexander WG, King SB, Hittinger CT, Rokas A. Dynamic evolution of nitric oxide detoxifying flavohemoglobins, a family of single-protein metabolic modules in bacteria and eukaryotes. Mol Biol Evol . 2016; 33: 1979– 1987. Google Scholar CrossRef Search ADS PubMed  115. Nielsen K, Heitman J. Sex and virulence of human pathogenic fungi. Dunlap JC, ed. Adv Genet . 2007; 57: 143– 173. Google Scholar CrossRef Search ADS   116. Heitman J, Carter DA, Dyer PS, Soll DR. Sexual reproduction of human fungal pathogens. Cold Spring Harb Perspect Med . 2014; 4: a019281. Google Scholar CrossRef Search ADS   117. Ianiri G, Averette A, Kingsbury JM, Heitman J, Idnurm A. Gene function analysis in the ubiquitous human commensal and pathogen Malassezia genus. MBio . 2016; 7: e01853. Google Scholar CrossRef Search ADS PubMed  118. Boekhout T, Kamp M, Guého E. Molecular typing of Malassezia species with PFGE and RAPD. Med Mycol . 1998; 36: 365– 372. Google Scholar CrossRef Search ADS PubMed  119. DeAngelis YM, Gemmer CM, Kaczvinsky JR, Kenneally DC, Schwartz JR, Dawson TL. Three etiologic facets of dandruff and seborrheic dermatitis: Malassezia fungi, sebaceous lipids, and individual sensitivity. J Investig Dermatol Symp Proc . 2005; 10: 295– 297. Google Scholar CrossRef Search ADS PubMed  120. Gaitanis G, Velegraki A, Mayser P, Bassukas ID. Skin diseases associated with Malassezia yeasts: facts and controversies. Clin Dermatol . 2013; 31: 455– 463. Google Scholar CrossRef Search ADS PubMed  121. Gupta AK, Bluhm R, Summerbell R. Pityriasis versicolor. J Eur Acad Dermatol Venereol . 2002; 16: 19– 33. Google Scholar CrossRef Search ADS PubMed  122. Saadatzadeh MR, Ashbee HR, Holland KT, Ingham E. Production of the mycelial phase of Malassezia in vitro. Med Mycol . 2001; 39: 487– 493. Google Scholar CrossRef Search ADS PubMed  123. Lee WJ, Kim JY, Song CH et al.   Disruption of barrier function in dermatophytosis and pityriasis versicolor. J Dermatol . 2011; 38: 1049– 1053. Google Scholar CrossRef Search ADS PubMed  124. Larangeira de Almeida H, Mayser P. Absence of sunburn in lesions of pityriasis versicolor alba. Mycoses . 2006; 49: 516– 516. Google Scholar CrossRef Search ADS PubMed  125. Mittermann I, Wikberg G, Johansson C et al.   IgE sensitization profiles differ between adult patients with severe and moderate atopic dermatitis. PLoS One . 2016; 11: e0156077. Google Scholar CrossRef Search ADS PubMed  126. Ishii K, Hiragun M, Hiragun T et al.   A human monoclonal IgE antibody that binds to MGL_1304, a major allergen in human sweat, without activation of mast cells and basophils. Biochem Biophys Res Commun . 2015; 468: 99– 104. Google Scholar CrossRef Search ADS PubMed  127. Hiragun M, Hiragun T, Ishii K et al.   Elevated serum IgE against MGL_1304 in patients with atopic dermatitis and cholinergic urticaria. Allergol Int . 2014; 63: 83– 93. Google Scholar CrossRef Search ADS PubMed  128. Gaitanis G, Magiatis P, Hantschke M, Bassukas ID, Velegraki A. The Malassezia genus in skin and systemic diseases. Clin Microbiol Rev . 2012; 25: 106– 141. Google Scholar CrossRef Search ADS PubMed  129. Jourdain R, Moga A, Vingler P et al.   Exploration of scalp surface lipids reveals squalene peroxide as a potential actor in dandruff condition. Arch Dermatol Res . 2016; 308: 153– 163. Google Scholar CrossRef Search ADS PubMed  130. Magiatis P, Pappas P, Gaitanis G et al.   Malassezia yeasts produce a collection of exceptionally potent activators of the Ah (dioxin) receptor detected in diseased human skin. J Invest Dermatol . 2013; 133: 2023– 2030. Google Scholar CrossRef Search ADS PubMed  131. Vlachos C, Gaitanis G, Alexopoulos EC, Papadopoulou C, Bassukas ID. Phospholipase activity after β-endorphin exposure discriminates Malassezia strains isolated from healthy and seborrhoeic dermatitis skin. J Eur Acad Dermatology Venereol . 2013; 27: 1575– 1578. Google Scholar CrossRef Search ADS   132. Hald M, Arendrup MC, Svejgaard EL et al.   Evidence-based Danish guidelines for the treatment of Malassezia-related skin diseases. Acta Derm Venereol . 2015; 95: 12– 19. Google Scholar CrossRef Search ADS PubMed  133. Negre A, Bensignor E, Guillot J. Evidence-based veterinary dermatology: a systematic review of interventions for Malassezia dermatitis in dogs. Vet Dermatol . 2009; 20: 1– 12. Google Scholar CrossRef Search ADS PubMed  134. Jesus FPK, Lautert C, Zanette RA et al.   In vitro susceptibility of fluconazole-susceptible and -resistant isolates of Malassezia pachydermatis against azoles. Vet Microbiol . 2011; 152: 161– 164. Google Scholar CrossRef Search ADS PubMed  135. Cafarchia C, Figueredo LA, Favuzzi V et al.   Assessment of the antifungal susceptibility of Malassezia pachydermatis in various media using a CLSI protocol. Vet Microbiol . 2012; 159: 536– 540. Google Scholar CrossRef Search ADS PubMed  136. Iatta R, Figueredo LA, Montagna MT, Otranto D, Cafarchia C. In vitro antifungal susceptibility of Malassezia furfur from bloodstream infections. J Med Microbiol . 2014; 63: 1467– 1473. Google Scholar CrossRef Search ADS PubMed  137. Gupta A, Foley K. Antifungal treatment for pityriasis versicolor. J Fungi . 2015; 1: 13– 29. Google Scholar CrossRef Search ADS   138. Arendrup MC, Boekhout T, Akova M et al.   ESCMID and ECMM joint clinical guidelines for the diagnosis and management of rare invasive yeast infections. Clin Microbiol Infect . 2014; 20: 76– 98. Google Scholar CrossRef Search ADS PubMed  139. Nakamura Y, Kano R, Murai T, Watanabe S, Hasegawa A. Susceptibility testing of Malassezia species using the urea broth microdilution method. Antimicrob Agents Chemother . 2000; 44: 2185– 2186. Google Scholar CrossRef Search ADS PubMed  140. Rincon S, Cepero de Garcia MC, Espinel-Ingroff A. A Modified Christensen's urea and CLSI broth microdilution method for testing susceptibilities of six Malassezia species to voriconazole, itraconazole, and ketoconazole. J Clin Microbiol . 2006; 44: 3429– 3431. Google Scholar CrossRef Search ADS PubMed  141. Yurayart C, Nuchnoul N, Moolkum P et al.   Antifungal agent susceptibilities and interpretation of Malassezia pachydermatis and Candida parapsilosis isolated from dogs with and without seborrheic dermatitis skin. Med Mycol . 2013; 51: 721– 730. Google Scholar CrossRef Search ADS PubMed  142. Carrillo-Muñoz AJ, Rojas F, Tur-Tur C et al.   In vitro antifungal activity of topical and systemic antifungal drugs against Malassezia species. Mycoses . 2013; 56: 571– 575. Google Scholar CrossRef Search ADS PubMed  143. Rojas FD, Sosa M d. l. A, Fernandez MS, Cattana ME, Cordoba SB, Giusiano GE. Antifungal susceptibility of Malassezia furfur, Malassezia sympodialis, and Malassezia globosa to azole drugs and amphotericin B evaluated using a broth microdilution method. Med Mycol . 2014; 52: 641– 646. Google Scholar CrossRef Search ADS PubMed  144. Velegraki A, Alexopoulos EC, Kritikou S, Gaitanis G. Use of fatty acid RPMI 1640 media for testing susceptibilities of eight Malassezia species to the new triazole posaconazole and to six established antifungal agents by a modified NCCLS M27-A2 microdilution method and Etest. J Clin Microbiol . 2004; 42: 3589– 3593. Google Scholar CrossRef Search ADS PubMed  145. Álvarez-Pérez S, García ME, Peláez T, Blanco JL. Genotyping and antifungal susceptibility testing of multiple Malassezia pachydermatis isolates from otitis and dermatitis cases in pets: is it really worth the effort? Med Mycol . 2016; 54: 72– 79. Google Scholar PubMed  146. Peano A, Pasquetti M, Chiavassa E. Superficial mycoses in dogs and cats. Summa Anim da Compagnia . 2012; 4: 40– 55 [Micosi superficiali del cane e del gatto]. 147. Breu F, Guggenbichler S, Wollmann J. Superficial Mycoses in Dogs and Cats . Worcestershire: NCAPP; 2011. 148. Ahman S, Perrins N, Bond R. Treatment of Malassezia pachydermatis-associated seborrhoeic dermatitis in Devon Rex cats with itraconazole—a pilot study. Vet Dermatol . 2007; 18: 171– 174. Google Scholar CrossRef Search ADS PubMed  149. Berger DJ, Lewis TP, Schick AE, Stone RT. Comparison of once-daily versus twice-weekly terbinafine administration for the treatment of canine Malassezia dermatitis—a pilot study. Vet Dermatol . 2012; 23: 418– e479. Google Scholar CrossRef Search ADS PubMed  150. Gupta AK, Bluhm R. Seborrheic dermatitis. J Eur Acad Dermatol Venereol . 2004; 18: 13– 26. Google Scholar CrossRef Search ADS PubMed  151. Tragiannidis A, Bisping G, Koehler G, Groll AH. Minireview: Malassezia infections in immunocompromised patients. Mycoses . 2010; 53: 187– 195. Google Scholar CrossRef Search ADS PubMed  152. Cafarchia C, Iatta R, Immediato D, Puttilli MR, Otranto D. Azole susceptibility of Malassezia pachydermatis and Malassezia furfur and tentative epidemiological cut-off values. Med Mycol . 2015; 53: 743– 748. Google Scholar CrossRef Search ADS PubMed  153. Rojas FD, Córdoba SB, de Los Ángeles Sosa M et al.   Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies. Mycoses . 2017; 60: 104– 111. Google Scholar CrossRef Search ADS PubMed  154. Leong C, Buttafuoco A, Glatz M, Bosshard PP. Antifungal susceptibility testing of Malassezia spp. with an optimized colorimetric broth microdilution method. J Clin Microbiol . 2017; 55: 1883– 1893. Google Scholar CrossRef Search ADS PubMed  155. Miranda KC, de Araujo CR, Costa CR, Passos XS, de Fátima Lisboa Fernandes O, do Rosário Rodrigues Silva M. Antifungal activities of azole agents against the Malassezia species. Int J Antimicrob Agents . 2007; 29: 281– 284. Google Scholar CrossRef Search ADS PubMed  156. Rodriguez-Tudela JL, Alcazar-Fuoli L, Mellado E, Alastruey-Izquierdo A, Monzon A, Cuenca-Estrella M. Epidemiological Cutoffs and Cross-Resistance to Azole Drugs in Aspergillus fumigatus. Antimicrob Agents Chemother . 2008; 52: 2468– 2472. Google Scholar CrossRef Search ADS PubMed  157. Pfaller MA, Diekema DJ. Progress in antifungal susceptibility testing of Candida spp. by use of clinical and laboratory standards institute broth microdilution methods, 2010 to 2012. J Clin Microbiol . 2012; 50: 2846– 2856. Google Scholar CrossRef Search ADS PubMed  158. Álvarez-Pérez S, Blanco JL, Peláez T, Cutuli M, García ME. In vitro amphotericin B susceptibility of Malassezia pachydermatis determined by the CLSI broth microdilution method and Etest using lipid-enriched media. Antimicrob Agents Chemother . 2014; 58: 4203– 4206. Google Scholar CrossRef Search ADS PubMed  159. Iatta R, Immediato D, Montagna MT, Otranto D, Cafarchia C. In vitro activity of two amphotericin B formulations against Malassezia furfur strains recovered from patients with bloodstream infections. Med Mycol . 2015; 53: 269– 274. Google Scholar CrossRef Search ADS PubMed  160. Mitsuyama J, Nomura N, Hashimoto K et al.   In vitro and in vivo antifungal activities of T-2307, a novel arylamidine. Antimicrob Agents Chemother . 2008; 52: 1318– 1324. Google Scholar CrossRef Search ADS PubMed  161. Fera MT, La Camera E, De Sarro A. New triazoles and echinocandins: mode of action, in vitro activity and mechanisms of resistance. Expert Rev Anti Infect Ther . 2009; 7: 981– 998. Google Scholar CrossRef Search ADS PubMed  162. Prohic A, KuskunovicVlahovljak S, Sadikovic T, Cavaljuga S. The Prevalence and species composition of Malassezia yeasts in patients with clinically suspected onychomycosis. Med Arch . 2015; 69: 81. Google Scholar CrossRef Search ADS PubMed  163. Iatta R, Puttilli MR, Immediato D, Otranto D, Cafarchia C. The role of drug efflux pumps in Malassezia pachydermatis and Malassezia furfur defence against azoles. Mycoses . 2016; 60: 178– 182. Google Scholar CrossRef Search ADS PubMed  164. Figueredo LA, Cafarchia C, Otranto D. Antifungal susceptibility of Malassezia pachydermatis biofilm. Med Mycol . 2013; 51: 863– 867. Google Scholar CrossRef Search ADS PubMed  165. Angiolella L, Leone C, Rojas F, Mussin J, de los Angeles Sosa M, Giusiano G. Biofilm, adherence, and hydrophobicity as virulence factors in Malassezia furfur. Med Mycol . March 2017. 166. Sanmiguel A, Grice EA. Interactions between host factors and the skin microbiome. Cell Mol Life Sci . 2015; 72: 1499– 1515. Google Scholar CrossRef Search ADS PubMed  167. Czurda S, Smelik S, Preuner-Stix S, Nogueira F, Lion T. Occurrence of fungal DNA contamination in PCR reagents: approaches to control and decontamination. J Clin Microbiol . 2016; 54: 148– 152. Google Scholar CrossRef Search ADS PubMed  168. Celis AM, Vos AM, Triana S et al.   Highly efficient transformation system for Malassezia furfur and Malassezia pachydermatis using Agrobacterium tumefaciens-mediated transformation. J Microbiol Methods . 2017; 134: 1– 6. Google Scholar CrossRef Search ADS PubMed  169. Kumar S, Stecher G, Tamura K. MEGA7: Molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol Biol Evol . 2016; 33: 1870– 1874. Google Scholar CrossRef Search ADS PubMed  170. Al-Sweih N, Ahmad S, Joseph L, Khan S, Khan Z. Malassezia pachydermatis fungemia in a preterm neonate resistant to fluconazole and flucytosine. Med Mycol Case Rep . 2014; 5: 9– 11. Google Scholar CrossRef Search ADS PubMed  171. Oliveri S, Trovato L, Betta P, Romeo MG, Nicoletti G. Malassezia furfur fungaemia in a neonatal patient detected by lysis-centrifugation blood culture method: first case reported in Italy. Mycoses . 2011; 54: e638– 640. Google Scholar CrossRef Search ADS PubMed  172. Chu CM, Lai RW. Malassezia furfur fungaemia in a ventilator-dependent patient without known risk factors. Hong Kong Med J . 2002; 8: 212– 214. Google Scholar PubMed  173. Barber GR, Brown AE, Kiehn TE, Edwards FF, Armstrong D. Catheter-related Malassezia furfur fungemia in immunocompromised patients. Am J Med . 1993; 95: 365– 370. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Medical Mycology Oxford University Press

Loading next page...
 
/lp/ou_press/malassezia-ecology-pathophysiology-and-treatment-6aYbnp09ax
Publisher
Oxford University Press
Copyright
© The Author(s) 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
ISSN
1369-3786
eISSN
1460-2709
D.O.I.
10.1093/mmy/myx134
Publisher site
See Article on Publisher Site

Abstract

Abstract Malassezia are lipid dependent basidiomycetous yeasts that inhabit the skin and mucosa of humans and other warm-blooded animals, and are a major component of the skin microbiome. They occur as skin commensals, but are also associated with various skin disorders and bloodstream infections. The genus currently comprises 17 species and has recently been assigned its own class, Malasseziomycetes. Importantly, multiple Malassezia species and/or genotypes may cause unique or similar pathologies and vary in their antifungal susceptibility. In addition to culture-based approaches, culture-independent methods have added to our understanding of Malassezia presence and abundance and their relationship to pathogenicity. Moreover, these novel approaches have suggested a much wider-spread presence, including other human body parts and even other ecosystems, but their role in these arenas requires further clarification. With recent successful transformation and genetic engineering of Malassezia, the role of specific genes in pathogenesis can now be studied. We suggest that characterizing the metabolic impact of Malassezia communities rather than species identification is key in elucidation of pathophysiological associations. Finally, the increasing availability of genome sequences may provide key information aiding faster diagnostics, and understanding of the biochemical mechanisms for Malassezia skin adaptation and the design of future drugs. Malassezia, biodiversity, mycobiome, skin, antifungal, disease mechanisms Introduction Malassezia are lipid dependent basidiomycetous yeasts that inhabit the skin and mucosal sites of humans and other warm-blooded animals. They are a major component of the skin mycobiome, based on both culture-based and culture-independent methods that used ITS length polymorphisms assessed by polymerase chain reaction (PCR),1 ITS meta-barcoding, and whole genome shotgun metagenomics.2,3 Various Malassezia species occur on human and animal skin as commensals, and they are associated with multiple skin disorders, such as pityriasis versicolor (PV), Malassezia folliculitis (MF), seborrheic dermatitis/dandruff (D/SD), atopic dermatitis (AD), and psoriasis.4 Use of catheters for parenteral nutrition can lead to Malassezia-caused bloodstream infections in immunocompromised patients or premature infants.5,6 A recent molecular phylogenetic study using six genes suggested the genus is deeply rooted in the Ustilaginomycotina with a sister relationship to Ustilaginomycetes and Exobasidiomycetes. Hence, the genus was assigned as its own class, Malasseziomycetes.7 These findings were confirmed by a phylogenomics approach based on complete genome sequences of 24 Malassezia isolates from 14 species.8 For many decades, the genus consisted of only two species, the lipid-dependent M. furfur and the apparent lipophilic M. pachydermatis. Since then, many more species have been described, initially using the D1/D2 domains of the large subunit of the ribosomal DNA (LSU rDNA) and the internal transcribed spacer regions (ITS) 1 and 2 (including the 5.8S rDNA).9 More recently, additional loci were added, including chitin synthase-2 (CHS2), β-tubulin, and translation elongation factor 1 alpha (TEF1).10–12 The phylogenomics study mentioned above used 164 core eukaryotic genes and identified three main species clusters: Cluster A consisting of species known mainly human skin, that is, M. furfur, M. japonica, M. obtusa, and M. yamatoensis; subcluster B1, with the most abundantly occurring human skin inhabitants M. globosa and M. restricta; subcluster B2 consisting of M. sympodialis, M. dermatis, M. caprae, M. equina, M. nana, and M. pachydermatis; and Cluster C that forms a basal lineage with M. cuniculi and M. slooffiae.8 Since then, three new species were described, namely, M. brasiliensis and M. psittaci from parrots11 and M. arunalokei from human skin.12 Thus at present the genus comprises 17 species. Phylogenetic relationships of these 17 species based on D1D2 domains of LSU rDNA are shown in Figure 1 and are largely in agreement with the previous phylogenomics data. Figure 1. View largeDownload slide Phylogenetic tree of the currently accepted 17 Malassezia species based on sequences of the D1D2 domains of the LSU rRNA gene, inferred using the Maximum Parsimony method with 1000 bootstrap replications. Tree 1 out of 5 most parsimonious trees (length = 377) is shown. The consistency index is 0.531250, the retention index is 0.689922, and the composite index is 0.470319 for all sites and 0.366521 for parsimony-informative sites. The tree is drawn to scale, with branch lengths calculated as number of changes over the full sequence. There were a total of 516 positions in the final data set and the evolutionary analysis was conducted in MEGA7.169 Figure 1. View largeDownload slide Phylogenetic tree of the currently accepted 17 Malassezia species based on sequences of the D1D2 domains of the LSU rRNA gene, inferred using the Maximum Parsimony method with 1000 bootstrap replications. Tree 1 out of 5 most parsimonious trees (length = 377) is shown. The consistency index is 0.531250, the retention index is 0.689922, and the composite index is 0.470319 for all sites and 0.366521 for parsimony-informative sites. The tree is drawn to scale, with branch lengths calculated as number of changes over the full sequence. There were a total of 516 positions in the final data set and the evolutionary analysis was conducted in MEGA7.169 Rapid and accurate identification of Malassezia from clinical samples is of importance for correct diagnosis and treatment. Traditionally, identification of Malassezia has been culture based using morphologic and biochemical features, such as utilization of Tweens and cremophore EL, catalase activity and growth at different temperatures. These conventional methods showed limitations with regards to differentiation between closely related species, are time consuming, and have a high error rate.13 In routine clinical laboratories, Malassezia-related disorders and infections likely are underdiagnosed as standard nonlipid supplemented media, such as Sabouraud glucose agar (SGA), do not support Malassezia growth, and delay correct identification and treatment. Likewise, the absence of species identification limits epidemiological knowledge regarding Malassezia-related disorders and infections.14,15 Several improvements have been made in Malassezia identification. An overview regarding available molecular tools was published by Cafarchia et al.14 With the recent addition of two PCR-based methodologies,16,17 including identification of 11 species directly from patient samples,17 the range of identification tools was further expanded. Application of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification of Malassezia isolates15,18 removed the need for DNA extraction, requires relatively low consumable and reagent costs, and has a short turnaround time. Unfortunately, spectra of most species have not yet been included in available commercial databases. Finally, the number of available genome sequences of Malassezia species is increasing rapidly and offers a valuable resource for development of targeted nucleic acid based diagnostics. As whole genome sequencing becomes more affordable, comparison of full genomes for identification and epidemiology may soon be within reach. Biodiversity and ecology Culture-independent tools for examining complex microbial communities occurring in and on the human body opened opportunities for detection of species that would otherwise be missed using culture-based methods, due to slow or fastidious growth or the lack of appropriate conditions resembling the natural habitat. Originally, human microbiome studies mainly focused on prokaryotic inhabitants of the human body, but fungi have recently received more attention. Some older studies referred to in this review were performed before general application of molecular methods and employed phenotypic methods, such as microscopy and physiological characteristics for isolate identification. We include those studies as they significantly contribute to our understanding of the diversity and role of Malassezia yeasts on the human and animal body, but it cannot be ruled out that over time with the further application of molecular diagnostics the emerging epidemiological picture may evolve. Table 1 gives an overview of all currently known species, with their taxonomic cluster denomination (also see Fig. 1), most common hosts, and known disease/disorder associations in both humans and animals. Table 1. Overview of all currently described Malassezia species with their taxonomic cluster denomination (see Fig. 1), main hosts and main known disease/disorder associations in both humans and animals. species  Taxonomic cluster  Main hosts  Main known disease/disorder associations in humans  Main known disease/disorder associations in animals  References  Malassezia furfur  A  Man, bovine, elephant, pig, monkey, ostrich, pelican  Systemic infections, PV, D/SD    5,9,59,93  Malassezia brasiliensis  A  Parrot  -  -  11  Malassezia yamatoensis  A  Man  SD, AD  -  9,61  Malassezia psitaci  A  Parrot  -  -  11  Malassezia japonica  A  Man  AD  -  57  Malassezia obtusa  A  Man  D/SD, AD  -  9,93  Malassezia nana  B2  Cat, bovine, dog  -  otitis  93,97,98,99  Malassezia caprae  B2  Goat, equine  -  dermatitis  44  Malassezia sympodialis  B2  Man, equine, pig, sheep  Systemic infections, PV, D/SD, AD  otitis  9,26,42,43,93  Malassezia dermatis  B2  Man  AD    9,27,45  Malassezia equina  B2  Equine, bovine  -  dermatitis  44  Malassezia pachydermatis  B2  Dog, cat, carnivores, birds  Systemic infections  otitis, dermatitis  9,64,93,94,95  Malassezia globosa  B1  Man, cheetah, bovine  PV, D/SD, AD  otitis  9,26,93,100,101  Malassezia restricta  B1  Man  D/SD, AD  -  9,27,32,35  Malassezia arunalokei  B1  Man  D/SD  -  12  Malassezia cuniculi  C  Rabbit  -  -  93  Malassezia slooffiae  C  Man, pig, goat, sheep  D/SD  otitis, dermatitis  9  species  Taxonomic cluster  Main hosts  Main known disease/disorder associations in humans  Main known disease/disorder associations in animals  References  Malassezia furfur  A  Man, bovine, elephant, pig, monkey, ostrich, pelican  Systemic infections, PV, D/SD    5,9,59,93  Malassezia brasiliensis  A  Parrot  -  -  11  Malassezia yamatoensis  A  Man  SD, AD  -  9,61  Malassezia psitaci  A  Parrot  -  -  11  Malassezia japonica  A  Man  AD  -  57  Malassezia obtusa  A  Man  D/SD, AD  -  9,93  Malassezia nana  B2  Cat, bovine, dog  -  otitis  93,97,98,99  Malassezia caprae  B2  Goat, equine  -  dermatitis  44  Malassezia sympodialis  B2  Man, equine, pig, sheep  Systemic infections, PV, D/SD, AD  otitis  9,26,42,43,93  Malassezia dermatis  B2  Man  AD    9,27,45  Malassezia equina  B2  Equine, bovine  -  dermatitis  44  Malassezia pachydermatis  B2  Dog, cat, carnivores, birds  Systemic infections  otitis, dermatitis  9,64,93,94,95  Malassezia globosa  B1  Man, cheetah, bovine  PV, D/SD, AD  otitis  9,26,93,100,101  Malassezia restricta  B1  Man  D/SD, AD  -  9,27,32,35  Malassezia arunalokei  B1  Man  D/SD  -  12  Malassezia cuniculi  C  Rabbit  -  -  93  Malassezia slooffiae  C  Man, pig, goat, sheep  D/SD  otitis, dermatitis  9  Note: AD, atopic dermatitis; D/SD, dandruff / seborrheic dermatitis; MF, Malassezia (pityrosporum) folliculitis; PV, pityriasis versicolor. View Large Presence on the healthy human skin The relative abundance of fungi on human skin was found to be low compared to bacteria, but Malassezia yeasts were identified using culture-independent methods as the most abundant skin eukaryotes representing 50%–80% of the total skin mycobiome.2,3Malassezia species predominated on all sampled body sites except foot. Eleven Malassezia species were identified with M. restricta being predominant in the external auditory canal, retroauricular crease and glabella, and M. globosa on back, occiput and inguinal crease. All the remaining species were observed scattered across other body sites and with lower frequency. Fungal diversity was more dependent on body site than the individual, but as similar species distributions occurred 3 months after the initial sampling this suggests temporal stability of site-specific Malassezia communities.2 Reanalysis of these metagenomic datasets using a more complete set of Malassezia genomes demonstrated the presence of 12 species, with M. restricta and M. globosa by far the most abundant, distantly followed by M. sympodialis.8 Most studies surveyed whites of Western descent. A high throughput ITS1 sequencing analysis of 40 asymptomatic Chinese subjects in Hong Kong revealed 90% of the sequencing reads as M. restricta, distantly followed by M. globosa with 5.3%.19 Another study investigating 40 healthy Japanese subjects using a real-time PCR approach, showed that the Malassezia skin mycobiome differed by sex, body site, and season. Generally, in male subjects, M. restricta and M. globosa were most predominant, followed by M. dermatis, M. furfur, and M. sympodialis. In female subjects M. globosa and M. sympodialis were most predominant, followed by M. dermatis, M. restricta, and M. furfur.20 Nevertheless, a major sampling bias is present in skin mycobiome studies to date and future studies need to take this into account. Malassezia skin colonization begins immediately after birth and increases until 6–12 months of age.21 Colonization then remains relatively low until just prior to puberty, when sebaceous gland activation provides a better habitat and Malassezia populations rise to a stable level.4 Recent metagenomic evidence suggests that skin colonization varies according to age and puberty22 and hypothesized a protective effect due to increased Malassezia colonization in adults preventing colonization by more pathogenic species, specifically dermatophytes and other more pathogenic species found more commonly in children. Occurrence in human skin disorders and systemic infections Host factors such as gene-induced variation, environmental conditions, lifestyle, hygiene, and the immune system can cause shifts in skin microbial communities associated with disease.23 For example, molecular studies of temporal changes in skin mycobiota of Japanese Antarctic expedition researchers and astronauts showed a temporal change in colonization levels with different proportions of Malassezia species during periods of increased stress and inability to bathe or shower. Fungal diversity decreased during time in space, whereas colonization of Malassezia species increased.24,25 Oh et al. reported a significant decrease in community diversity as an indication of skin disease, but it remains unclear whether such changes occur at all taxonomic levels.3 Malassezia species have been associated with a number of skin conditions, including PV, a MF, D/SD, AD, and psoriasis.26,27 In a 26S rDNA-based pyrosequencing study of Japanese SD patients Malassezia was the most abundant fungal genus at both lesional and nonlesional sites. At lesional sites M. restricta predominated, and at nonlesional sites M. globosa and other species were detected but did not differ between sites.28 A recent culture-based study of individuals in India applying multiple molecular methods for species identification confirmed the predominance of M. globosa on scalps of control subjects, whereas on the scalps of SD patients the abundance of M. globosa was closely followed by M. restricta and M. furfur.12 Based on both phenotypic and PCR-based studies M. globosa is the species most frequently associated with human disease and linked to various dermatological conditions including PV and D/SD and it occasionally occurs on animal skin.1,26,27,29–33 M. restricta is the second most common species on healthy and diseased skin, particularly of scalp, neck, face, and ears27,31 and is associated with D/SD and AD.1,32,34–36 It was abundantly found on healthy skin but significantly more abundant at SD sites.28 A culture-independent study comparing healthy, nondandruff with dandruff scalp of French subjects found M. restricta as the most abundant fungal species in both but with a slightly higher colonization level on healthy scalp (97% vs. 84%).37 M. sympodialis is the third most abundant species on healthy human skin but appearing with significantly lower frequency when compared to M. globosa and M. restricta.8 It is also known from PV, AD, the skin of an AIDS patient, the auditory tract of a healthy 33-year-old male, and various animals. It must be noted that the majority of these findings are based on physiological, not molecular, identification.26,27,29,38–41 Occasionally, M. sympodialis is also found to cause systemic infections.42,43 M. caprae has been described from healthy skin of goats and equines44 and is less frequently found on human skin.8M. dermatis has been identified with low frequency from both healthy skin and lesions of AD patients.8,27,45 Utilization of culture-based methods identifies M. furfur on various body sites including human skin, blood, and urine. However, culture-independent studies found M. furfur on skin only rarely, with low frequency and abundance.1,2,8M. furfur has been identified from deep-seated infections, such as blood, urine, and vagina, often associated with immune compromised patients, or from septicemia in neonates that received lipid supplementation via catheters.5,46–52M. furfur was isolated from the skin of preterm-infants in a neonatal intensive care unit (NICU), with a prevalence varying according to gestational age, admission to the NICU and length of hospitalization.53,54 An Italian 1-year survey of yeast mediated fungemia in 290 neonates and 17 pediatric patients (age <16 years) using MALDI-TOF and sequencing for species identification resulted in eight cases (2.8%) in which M. furfur was identified as the causative agent. From all patients with M. furfur bloodstream infections the species was also isolated from skin.5 Based on multiple methods, such as PFGE, AFLP, and rDNA sequence analysis, considerable intra-species variation was observed and it has been suggested that a specific AFLP genotype is more frequently involved in deep-seated infections.55,56 Another study evaluated catheter-associated M. furfur strains and found that all isolates recovered from blood cultures and catheter tips belonged to the specific subtype I-3.52 M. japonica is a rare species isolated from healthy human skin of a Japanese woman and AD patients.57M. obtusa has been identified from human groin, the nasal vestibule, and human AD but also from animals.58–60M. yamatoensis is known from SD and AD patients as well as healthy human skin.27,61 During a recent survey of SD in India, a new species M. arunalokei was found on scalp and in the nasolabial folds of both healthy subjects and D/SD patients.12 Based on mycobiome investigations, M. pachydermatis has been observed in the sputum from asthma patients62 and in the nasal vestibule of healthy subjects and patients with allergic rhinitis (AR).60 The species causes catheter-related septicemia in neonates that receive lipid supplementation,29,51,55,63–70 and it has been associated with sepsis and bloodstream infections in immunosuppressed adults.71,72M. pachydermatis is considered zoophilic and is only rarely isolated from human skin.4,8,73 However, it may colonize the hands of pet owners and when PCR was used as the detection technique the prevalence of hand colonization was found to be high (i.e., 93%).74 A possible zoonotic infection route was suggested when pet dogs were identified as a source for transmission of the species to neonates via the hands of health care workers.68 The in vitro production by Malassezia species of Aryl hydrocarbon receptor (AhR) indolic ligands from tryptophan changed our views on the biochemistry of these species. An array of bioactive indoles is produced by Malassezia species. The significance of this observation was expanded when it was associated with M. furfur pathogenic potential and was also shown to happen by the other, more common Malassezia species. Furthermore, these indols may also be formed in vivo as they were found in significantly higher quantities in SD skin scales as compared to healthy controls. Malassezia yeasts both in vitro and in vivo produce potent AhR ligands, that is, formyl-indolo [3,2-b] carbazole (FICZ) and indolo [3,2-b] carbozole (ICZ). The ability to activate the AhR receptor and thus modulate down-stream effects places Malassezia yeasts within two significant pathophysiological pathways, mediation of ultraviolet damage and modulation of the host immune response. These observations, together with the anatomic co-localization of Malassezia yeasts with basal cell carcinoma, led to the hypothesis that they could be implicated in skin carcinogenesis.6,75,76 More studies are needed to gain a better overview of the abundance and role of Malassezia species in the microbiome of healthy and diseased skin of male and females from various ethnicities, different locations, climates, and life styles. It will be especially important to consider long-term (years) longitudinal studies of lesional and healthy skin among genetically related humans.77 Presence in other human body sites A mycobiome analysis of the nasal vestibule of AR and healthy subjects identified 69 fungal genera of which Malassezia was predominant. At least six species were found in all subjects: M. restricta, M. globosa, M. sympodialis, M. slooffiae, M. dermatis, and M. pachydermatis. One sample contained M. cuniculi and M. obtusa. M. restricta represented the vast majority (>86%) in both subject groups. At the species level, two AR subjects showed a notably higher diversity compared to healthy individuals.60 Another study characterized the sinus fungal communities of 23 chronic rhinosinusitis (CRS) patients and 11 controls. Malassezia was the most prevalent fungus and detected in all patients and controls.78,79 Presently available data suggests that Malassezia species are commensals of the nasal cavity, but any role in AR and CRS needs further clarification. Conflicting data exist regarding the oral microbiome. Malassezia were reported to be present with high abundance in the oral microbiome of six subjects, suggesting it may be a prominent oral commensal,80 but reevaluation using more Malassezia genomes failed to confirm this result.8 Culture-based studies and one culture-independent study also failed to confirm the presence of Malassezia in the oral microbiome.81,82 Dupuy et al. suggested that the unexpected findings may be related to the use of an improved harsh cell lysis method,80,82 but this fails to explain why Malassezia were not found in a reanalysis of their sequencing data. Malassezia was also found a dominant oral mycobiome inhabitant in a leukemia patient with mucormycosis.83 In a study that characterized the microbiome of human root canal infections, Malassezia was the second most frequently identified fungal genus after Candida spp., albeit only in two out of six analyzed teeth and with a low abundance.84 With respect to other body sites, two studies found Malassezia spp. in sputum samples of cystic fibrosis (CF) patients but with lower abundances than Candida spp.85,86 Finally, Malassezia species have been found in stool, but more research is needed to clarify whether they belong to the commensal human gut mycobiota.87–90 Malassezia on animals and other habitats Malassezia have been isolated from a variety of animals, including cats, dogs, horses, goats, pigs, and rabbits,91–93 both as commensals and linked to diseased skin. M. brasiliensis and M. psittaci, two recently described species using sequencing analysis of three loci, originated from parrots in Brazil.11M. pachydermatis is the most frequently isolated species from skin of all animals investigated, except rabbits and goats. M. pachydermatis has a high intraspecies diversity, and certain genetic subtypes may have host specificity.94,95M. slooffiae has been reported from bovines, goats, cats, and healthy pigs, but these findings were mostly based on phenotypic identifications.91,96 A sequencing-based study showed that M. caprae was primarily isolated from healthy goats, and M. equina mainly from healthy horse.44 Using sequencing and other molecular methods M. nana has been identified in the ear canal of cats with otitis externa, in cows with and without otitis externa from Brazil,97 in healthy and diseased cats from the UK and Spain,98 and it has been suggested to be the predominant Malassezia species occurring in ears from horses.99 Using phenotypic identifications, M. globosa has been encountered on skin and healthy or otitic ears from cows and on horses that are either healthy or suffer from dermatomycoses.96,100,101M. sympodialis was the most common species found on healthy cattle in Brazil100 but has to a lesser extent also been isolated from healthy equines and other animals.59,96,100,101M. furfur has been isolated from various animals, including elk, elephant, ostrich, goat, dog, cat, and, more frequently, from cattle and equines.59,96,100,101 Most studies describing Malassezia species from animals are culture- and phenotype based, and further culture-independent surveys are needed to compare with the Malassezia communities occurring on humans. Malassezia species were originally thought to be specifically associated with mammalian hosts, but culture-independent studies revealed they may occur in a much broader diversity of habitats, including terrestrial and marine ecosystems such as deep-sea sediments, (Antarctic) soils, corals, sponges, nematodes,102–104 and cone snails.105 Furthermore, Malassezia DNA was detected from soil nematodes in Central European forests, and it has been hypothesized that nematodes may serve as a vector for Malassezia species.106 In a Brazilian study that investigated 45 cows with bilateral otitis nematodes were found in the ears of all subjects and Malassezia yeasts in 69% of the ears, suggesting a possible relationship between nematodes and Malassezia yeasts.107 Finally, in a recent metabarcoding survey on the fungal microbiome of the olive fruit fly, Malassezia was identified as one of the core associated fungi, albeit with low relative abundance.108 More research is needed to clarify the presence and role of Malassezia species in these and other habitats and their possible interactions with other members of the microbial communities and their vertebrate and invertebrate hosts. Advances in comparative genomics To date, the complete genomes of 29 Malassezia isolates have been reported, including 14 species and multiple isolates of the most common inhabitants of human skin, that is, M. globosa, M. restricta, and M. sympodialis,8,109M. pachydermatis, the most common veterinary species,110 and M. furfur, a species that causes most invasive infections and sepsis.8 These studies also included comparison to divergent fungal genomes, indicating features that define the Malassezia genus. Malassezia genomes are compact and well adapted to a specific ecological niche, as evidenced by loss of multiple common fungal gene families and multiplication of others.111Malassezia have a propensity for gene turnover, and the losses and gains are focused on gathering of necessary nutrients from a sparse environment via secretion of large families of lipases, phospholipases, aspartyl proteases, and other enzymes for degradation of skin. Interestingly, comparison of Malassezia to other fungi resident on humans or plants emphasizes “niche specific evolution.”111Malassezia express multiple secreted hydrolases, similar to Candida albicans, another opportunistic human skin pathogen. Candida is not phylogenetically related to Malassezia but its enzyme repertoire also aims to degrade proteins and fat. Similarly to Malassezia, Ustilago produces a set of secreted enzymes for degradation of their local host, but as Ustilago is a plant pathogen the enzymes target degradation of plant specific proteins, cutin, and waxes.8,112 All Malassezia have lost the main enzymes required for lipid metabolism, including fatty acid synthase (FAS), Δ9 desaturase, and Δ2, 3enoyl CoA isomerase.8,111,113 Therefore, they cannot produce fatty acids themselves but need lipids from the environment for growth. Comparative genomics coupled with phenotypic characterization also led to the conclusion that M. pachydermatis, previously thought to be lipid independent and lipophyllic, is actually lipid dependent along with all other Malassezia species. Comparative genomics also revealed 13 Malassezia-specific functional domains, mainly containing genes of unknown function. One example of a gene gain event is that of a single gene, belonging to the PFam domain PF06742 with unknown function, which is conserved in all Malassezia but absent in any other sequenced Basidiomycetes, implying a gene transfer event which predates the genesis of the genus.8 The gene is functionally expressed in M. globosa and its transcription regulated. A second potentially horizontally transferred gene was predicted to be a catalase that matched the PFam domain PF00199. This catalase may be potentially adaptive as it may protect Malassezia cells from their own secreted hydrogen peroxide generating proteins.8 Finally, another Malassezia HGT is the acquisition of flavohemoglobin A from the bacterial genus Corynebacterium, increasing NO resistance.114 These gene families have undergone multiple lineage-specific duplications and then further divergence. The most parsimonious explanation for the genus-wide variation in these gene families may be related to each species’ niche-specificity. Malassezia genomics also revealed they are likely to mate,8,109,111 which may increase their virulence as a result of higher genetic diversity.115,116 The structure of the mating loci suggest pseudo-bipolar mating in all Malassezia where the sequence assembly is strong enough to support structural determination of the region.8,117 Isolates belonging to M. furfur show significant genomic and phenotypic divergence, including isolates with: significantly larger genomes; duplicate copies of multiple genes; and differing karyotype patterns, taken together suggesting a hybridization event.8,55,111,118 Ongoing studies are attempting to disentangle the complexity of these M. furfur isolates and other genetically diverse species, such as M. globosa and M. pachydermatis. Epidemiology and pathophysiology of a complex relationship Malassezia yeasts are eukaryotic fungal skin commensals that must cope in their cutaneous niche with stimuli and perturbations that originate both from the host and the external environment. In addition, host susceptibility is critical.119,120 Thus, from the point of view of human pathology we may consider Malassezia as pathophysiologic effectors acting within a narrow, yet omnipresent transitional (intermediary) zone positioned in between the “self” body compartment, the skin, and the “non-self,” ‘outer’ environment (Fig. 2). Moreover, Malassezia populations occurring within the “transitional zone” are dynamically modified by and also respond to homeostatic reactions of the underlying skin (Fig. 2). In this view, we should not adhere to the concept of pathogenic versus apathogenic Malassezia species as fundamentally understood by the Koch postulates. On the contrary, we should address the impact of the metagenome (secretome, proteome) functional plasticity of the diverse Malassezia species and their constituting populations occurring within an anatomical area and the relevant impact they have on the skin of susceptible individuals with or without excess yeast proliferation, as is the case in PV, and D/SD and AD, respectively. Figure 2. View largeDownload slide Schematic representation of the interaction spectrum between Malassezia, the skin and the environment. Note: AD, atopic dermatitis; D/SD, seborrheic dermatitis /dandruff; PV, pityriasis versicolor. This Figure is reproduced in color in the online version of Medical Mycology. Figure 2. View largeDownload slide Schematic representation of the interaction spectrum between Malassezia, the skin and the environment. Note: AD, atopic dermatitis; D/SD, seborrheic dermatitis /dandruff; PV, pityriasis versicolor. This Figure is reproduced in color in the online version of Medical Mycology. In PV, there is a population burst of Malassezia which proliferate abundantly under favorable environmental conditions (e.g., enhanced heat, humidity). Reversing the aggravating disease conditions can promptly resolve PV without any specific therapy.121 Moreover, in this condition Malassezia cells massively acquire a distinctive hyphal morphology that probably denotes the profuse availability of nutrients,122 which does not only secure the opportunity of the yeast to reproduce freely but also their ability to spread on the skin surface and perhaps to mate with cells from distinct populations of neighboring yeast settlements, for example, from adjacent hair follicles. This would be suggestive of a condition analogous to microbial biofilms. Furthermore, from a clinical point of view, the almost 80% relapse rates after antifungal treatments is disappointing as it only temporarily reduces the colonizing yeast numbers without removing the underlying environmental cause. The pathophysiology of PV lesions includes minor changes in skin barrier function123 or even a potentially protecting UV-filtering action of the Malassezia biofilm.124 The observation of useful skin adaptations as a consequence of Malassezia proliferation further underscores the concept of a pliable, physiological ‘transitional mantel zone’ that enables a gradual transition between skin surface and environment. This ‘zone,’ is by nature “external” to the human body, yet it is also an area of significant compositional plasticity as the diverse effects of the underlying healthy or diseased skin could decisively modify it. Regarding the impact of Malassezia in AD and D/SD, Malassezia induce skin disease through two—not mutually exclusive but potentially interacting—induction mechanisms, namely, allergic and irritant pathways (Fig. 2). In AD, a sensitization state against Malassezia antigens seems to be almost universal. An array of well-characterized allergens with immunoglobulin E (IgE) binding ability has been described in AD patient disease exacerbations (as well as in patients with cholinergic urticaria), mostly of M. furfur and M. sympodialis, and more recently from M. globosa.125,126 The detection rate of IgE sensitization only to M. sympodialis antigens reaches 60% in severe AD patients.125 Similarly, high sensitization rates of patients with the same diagnosis have been described for M. globosa antigens.127 Possible explanations could include (1) the presence of an undetected persistent population of sensitizing species in skin sanctuaries, like the hair infudibulum, or (2) substantial turn-over in the species that colonize the skin in different life periods thus favoring multiple sensitization events. Additionally, a selectivity of these species for AD cannot be excluded. Thus, in the case of AD the involvement of Malassezia seems to be that of an unavoidable source of constantly synthesized allergens in close vicinity to the susceptive skin within the proposed ‘transitional zone’. The pathophysiological significance of an omnipresent allergen source could be further elaborated in future studies with a focus on allergen expressing behavior of all Malassezia species and also the identification of additional IgE binding Malassezia macromolecules at species and strains level. On the other hand, specific IgE antibodies against Malassezia species are absent to sparse in SD,128 and current data point toward an irritant and/or toxic effect of Malassezia metabolic products on predisposed susceptible skin as the pathophysiologic equivalent. These include lipid hydrolysis products, squalene peroxides, and indolic compounds.119,129,130 Most of these biologically active substances can also be produced by the action of UV light on the skin (e.g., squalene peroxides, L-tryptophan photoproducts), albeit to a lesser degree, a fact that highlights the complexity of the human skin—Malassezia—environmental interactions. The ability to modify the skin levels of these effectors by modulating their synthesis rates in yeast cells is expanded to almost all Malassezia species tested.130,131 Thus, restricting our focus to a particular species would end up with equivocal results. In order to unravel the pathobiology of Malassezia-associated diseases, it is important to comprehend the diversity of the pathogenic pathways that stems from a variety of possible interactions, namely, the higher degree of intraspecies diversity involved, that is, Malassezia species versus human skin, together with the respective metabolic plasticity of a eukaryote. On the other side, the human multicellular host may modify the outcome of this interaction by regulating (1) Malassezia species composition, (2) differential induction of the yeast metabolic pathways, and (3) relevant skin pathogenic pathways. Last but not least, environmental influences that affect both skin and Malassezia yeasts alike, for example, ambient humidity, UV level, and temperature, may lead to perplexing pathophysiologic interactions between human skin and yeasts. Thus elaborate future epidemiological studies, as done by Jo et al.22, could address the first question and guide subsequent Malassezia metabolome experiments to assess the possible roles of proteins, lipids, and bioactive molecules. Therapeutic approaches of Malassezia skin disorders and infections and anti-fungal susceptibility Malassezia are associated with a wide range of superficial diseases and nosocomial infections.6 Despite attempts with topical and systemic antifungals, a trend toward recurrence is often noticed.132,133 Moreover, there has been induction of in vitro fluconazole (FLZ) resistance in M. pachydermatis134,135 as well as treatment failure with terbinafine (TER) in PV patients or with FLZ or posaconazole (POS) in preventative treatment of Malassezia furfur fungemia,26,71,136,137 suggesting occurrence of resistance. Unfortunately, methods for in vitro susceptibility testing for Malassezia spp. have not been standardized,138 and published data describe variable azole susceptibility.136,139–145 Here we summarize data about the therapeutic approaches to Malassezia skin disorders and infections and in vitro antifungal activity of the most commonly employed drugs, that is, azoles, polyenes, allylamines, and echinocandins, against Malassezia yeasts. Therapeutic approaches for Malassezia skin disorders and infections Three classes of antifungals, that is, azoles, polyenes, and echinocandins, are used to manage fungal infections. Azoles and polyenes (amphotericin B, AmB), are frequently employed to treat Malassezia-related skin disorders or infections in humans and animals. For canine Malassezia dermatitis the European Scientific Counsel Companion Animal Parasites (ESCCAP) guideline146 concluded that there was good evidence supporting twice-weekly use of a 2% miconazole / 2% chlorhexidine shampoo. However, the employment of oral ketoconazole (KTZ-10 mg/kg, once daily) and oral itraconazole (ITZ-5 mg/kg, once daily) for 3 weeks was indicated for severe Malassezia-related disorders.133,147 Successive studies confirmed the previous results and indicated the efficacy of pulse administration of 5 mg/kg of ITZ or 30 mg /kg of terbinafine (TER) for at least 3 weeks in the treatment of Malassezia dermatitis in cats and dogs, respectively.148,149 For Malassezia-related human skin disorders, PV and SD patients might be sufficiently treated with topical agents, but maintenance therapy is usually suggested to prevent relapse.26,132,137,150 Even if the evidence for a causal relationship between Malassezia yeasts and atopic dermatitis remains to be better addressed, these yeast species are usually considered the exacerbating factor of atopic dermatitis (AD), and the patients show a good clinical improvement by use of ketoconazole.26 Topical KTZ shampoo (twice weekly) or miconazole cream (twice daily) is useful to treat also PV and SD.132 In particular, treatment of SD was traditionally performed using keratolytic agents or topical corticosteroids.132 However, based on the presumed causative association between Malassezia and SD, the current treatment option is primarily based on topical antifungal agents alone or in combination with corticosteroids.132 For widespread lesions of PV and in cases that are refractory to topical treatment, systemic therapy with FLZ (300 mg/week for 2–3 weeks) or ITZ (200 mg/day for 5 or 7 days up to 3 weeks) may be used.132,137 The effect of these two agents seems to be similar, but FLZ is usually preferred for PV and MF, and ITZ for SD. Oral use of TER seems ineffective in PV, possibly because of a more uneven yeast distribution at the skin surface.26,137,150 Systemic, catheter-related Malassezia infections are usually treated with catheter removal, administration of a systemic antifungal and in some cases by discontinuation of the lipid infusion.138 Intravenous treatment with AmB proved useful in both preterm infants and adults with blood stream infections (Table 2). FLZ, voriconazole (VOR), and posaconazole (POS) may represent alternative options, but clinical evidence suggests failure of these drugs to treat Malassezia fungemia (Table 2). Duration of treatment has not yet been defined, but a course of 14 days of effective antifungal therapy after the last positive blood culture and catheter removal is usually recommended similar to treatment of invasive Candida infections.151 Table 2. Prospective studies on the treatment of Malassezia spp. fungemia reporting clinical and mycological outcome. Species  Agent tested  Protocol  Length of treatment  Hosts  References  Malassezia sympodialis  Amphotericin B deoxycholate  1 mg/kg/day (accumulate dosage 20 mg/kg).  21 days  1 Preterm infant  42  Malassezia pachydermatis + mycobacteria  Liposomal Amphotericin B.+nafcillin  5 mg/kg/day IV  7 days  1 Adult  72  Malassezia pachydermatis  Liposomal Amphotericin B  1 mg/kg/day  NR  1 Adult with oral Posaconazolo prophylaxis  71  Malassezia pachydermatis  Liposomal Amphotericin B  nr  7 days  11 Preterm infant  170  Malassezia pachydermatis  Liposomal Amphotericin B alone or in combination with Flucytosine or Fluconazole  1 mg/kg/day 8 mg/kg/day PO or EV (50–150 mg kg/day PO)  3–5 weeks  8 Preterm neonates  70  Malassezia furfur  Liposomal Amphotericin B  4 mg/kg/day  45 days  1 Preterm infants  171  Malassezia furfur  Liposomal Amphotericin B  From 2.5 to 5 mg/kg  6–20 days  6 preterm infants, 3 with fluconazole prophylaxis  5  Malassezia furfur  Amphotericin B followed by Fluconazole  0.7 mg/ kg/day for10 days; 200 mg daily for 14 days  24 days  1 adult  172  Malassezia furfur  Amphotericin B  1 mg/kg/day  NR  4 adults and 3 children  173  Species  Agent tested  Protocol  Length of treatment  Hosts  References  Malassezia sympodialis  Amphotericin B deoxycholate  1 mg/kg/day (accumulate dosage 20 mg/kg).  21 days  1 Preterm infant  42  Malassezia pachydermatis + mycobacteria  Liposomal Amphotericin B.+nafcillin  5 mg/kg/day IV  7 days  1 Adult  72  Malassezia pachydermatis  Liposomal Amphotericin B  1 mg/kg/day  NR  1 Adult with oral Posaconazolo prophylaxis  71  Malassezia pachydermatis  Liposomal Amphotericin B  nr  7 days  11 Preterm infant  170  Malassezia pachydermatis  Liposomal Amphotericin B alone or in combination with Flucytosine or Fluconazole  1 mg/kg/day 8 mg/kg/day PO or EV (50–150 mg kg/day PO)  3–5 weeks  8 Preterm neonates  70  Malassezia furfur  Liposomal Amphotericin B  4 mg/kg/day  45 days  1 Preterm infants  171  Malassezia furfur  Liposomal Amphotericin B  From 2.5 to 5 mg/kg  6–20 days  6 preterm infants, 3 with fluconazole prophylaxis  5  Malassezia furfur  Amphotericin B followed by Fluconazole  0.7 mg/ kg/day for10 days; 200 mg daily for 14 days  24 days  1 adult  172  Malassezia furfur  Amphotericin B  1 mg/kg/day  NR  4 adults and 3 children  173  Note: NR, not reported. View Large Antimicrobial susceptibility profile of Malassezia species No reference method has been developed, and, hence culture media, inoculum sizes, incubation times, and criteria to determine MIC differ among studies.135,142,143,152 MICs of the most commonly employed drugs to treat dermatitis and/or fungemia are obtained using the modified CLSI broth microdilution test.136,139–145 Regardless of media or other conditions, evidence suggests that antifungal susceptibility profiles against azoles, AMB and TER vary according to species (Table 3). M. sympodialis and M. pachydermatis are the most susceptible, and M. furfur and M. globosa the least susceptible species.136,142,143,152 ITZ and KTZ were the most active for all Malassezia species, and FLZ, VOR, and AmB the least active.136,142,152,153 In particular, wide MIC ranges and higher intra-species variation to FCZ, VOR, and AmB were observed for M. furfur, M. sympodialis, and M. globosa.143,152–154 In addition, the MIC values for FLZ and ITZ of M. furfur isolates obtained from blood stream infected (BSI) patients were usually higher than those isolated from diseased human skin,140–142,144,152,155 suggesting the source of Malassezia might be pivotal in strain susceptibility.140–142,152 The VOR susceptibility is highly variable within M. furfur strains and the MIC values may be higher than those reported for other fungi (i.e., Candida spp. and/or Aspergillus spp.), thus showing a lower efficacy for M. furfur.138,152,155–157 Table 3. Range of MIC values obtained with modified CLSI protocols of Malassezia species from skin lesions and blood stream infections. Malassezia species  Host/lesion  FLZ  KTZ  ITZ  VRZ  POS  TER  AMB  References  Malassezia furfur  Human /SL  ≤0.125>128  ≤0.03–1  ≤0.03–16  ≤0.03–16  0.03-32  0.03-32  0.125 -16  136,140.142–144,152,153  Malassezia furfur  Human /BSI  0.5 > 128  ND  0.03–8  0.06–8  0.016–8  ND  0.25–16  136,152  Malassezia sympodialis  Human /SL  ≤0.125–16  0.015–4  ≤0.03–1  0.015–1  0.03-0.6  0.05–0.8  0.125–4  140,143,144,153  Malassezia globosa  Human /SL  ≤0.125–32  0.015––8  0.015––8  0.03–>8  0.03–0.06  0.03–16  0.1–4  140,143,144,153  Malassezia pachydermatis  Dogs /SL  1–>64  <0.008–4  0.03-4  0.06–8  0.008–4  0.063–2  0.06–0.5  135,140–142,144–145  Malassezia species  Host/lesion  FLZ  KTZ  ITZ  VRZ  POS  TER  AMB  References  Malassezia furfur  Human /SL  ≤0.125>128  ≤0.03–1  ≤0.03–16  ≤0.03–16  0.03-32  0.03-32  0.125 -16  136,140.142–144,152,153  Malassezia furfur  Human /BSI  0.5 > 128  ND  0.03–8  0.06–8  0.016–8  ND  0.25–16  136,152  Malassezia sympodialis  Human /SL  ≤0.125–16  0.015–4  ≤0.03–1  0.015–1  0.03-0.6  0.05–0.8  0.125–4  140,143,144,153  Malassezia globosa  Human /SL  ≤0.125–32  0.015––8  0.015––8  0.03–>8  0.03–0.06  0.03–16  0.1–4  140,143,144,153  Malassezia pachydermatis  Dogs /SL  1–>64  <0.008–4  0.03-4  0.06–8  0.008–4  0.063–2  0.06–0.5  135,140–142,144–145  Note: AmB, amphotericin B; BSI, blood stream infection; FLZ, fluconazole; ITZ, itraconazole; KTZ, ketoconazole; POS, posaconazole; SL, skin lesion; TER, terbinafine. View Large AMB is very active against M. pachydermatis158 but less so against M. furfur strains causing fungemia,153,159 which is linked to the AMB formulations.159 MICs of M. furfur were lower when liposomal AMB (l-AmB) was used, which may be due to the lipophilic nature of this yeast species.159 A higher efficacy of AmB (both l-AmB and AmB deoxycholate) was recorded for M. furfur strains coming from patients retreated with FLC, most likely due the synergic effect of azoles with AMB. This confirms that the combination of FLC plus AMB might be more effective toward a more rapid clearance of the BSI.152 The variations in susceptibility among Malassezia species to TER were greater compared to those obtained with the azole drugs (KTZ, ITZ, VOR, Table 2). M. furfur is less susceptible to TER than M. sympodialis and M. pachydermatis.144,145,153 For echinocandins limited data exist and the MIC values for M. furfur,160 that is, MIC >64 mg/l, need to be confirmed as Malassezia yeasts species are considered intrinsically resistant to these drugs as reported for other basidiomycetes fungi.138,161 Clinical outcome and in vitro susceptibility of Malassezia species The correlation of antifungal susceptibility with clinical outcome has been rarely reported and deserves further investigation. Preliminary results showed that FLZ high MIC values (i.e., >64 mg/l), correlated well with poor clinical response. Indeed, it has been shown that M. furfur strains originating from human patients receiving FLC prophylaxis (3 mg/Kg), but developing M. furfur BSI, presented high MIC values (i.e., >128),136 regardless of the media employed for testing in vitro susceptibility.136 On the contrary, high AmB MIC values were detected in M. furfur strains coming from patients with a positive clinical outcome with AmB therapy alone,159 thus suggesting the unsuitability of the methods, that is, media used, reading time as well inoculum concentration, employed to test the in vitro susceptibility.159 However, since similar results for the same Malassezia species (i.e., AmB MICs of M. furfur >2 mg/l) were obtained by other authors applying different methods,143,144 the high MIC values may be real and the positive outcome of patients might be due to the synergic effect of additional drugs.159 Indeed lower AMB MIC values were registered for M. furfur strains coming from BSI patients receiving FLC prophylaxis and treated with AMB, than those coming from patients treated with AMB alone.136,159 In addition, the high in vitro activity of AmB against M. pachydermatis using the same methodology suggests that the low M. furfur AmB susceptibility may be species dependent. Variations in quantity or type of sterols in cell membranes, as well as the inhibition of oxidative action of AmB due to high activity of fungal intracellular catalase and/or superoxide dismutase, may contribute to the low susceptibility of M. furfur to AMB.136,143,144 However, the observed incongruences between clinical outcome and in vitro-obtained susceptibility results need further investigation. Future, collaborative studies and clinical trials are essential for correlating in vitro results with clinical outcomes, but the data presented herein suggest that the high MICs of FLZ and VOR for Malassezia species indicate that they are not a good treatment option. The high susceptibility for AMB in M. furfur from BSI patients receiving FLC prophylaxis might indicate that AmB treatment should be combined with FLZ for a better prognosis. Guidelines for the treatment of Malassezia skin disorders have been assessed both for pet animals and humans, but those related to systemic mycoses are not available to date.138 Clinical evidence indicated the efficacy of azole drugs for the control of the skin disorders and of AmB for systemic infections.138 However, the common recurrence of skin disorders as well as the severity of infections suggests the use of high doses of antifungal agents for prolonged time periods.132,133,137,146 The observed high inter- and intra-species differences of Malassezia antifungal profiles may explain the differences observed in mycological cure rates when an antifungal agent is used to treat what appears to be clinically the same disease state. This can be due to different Malassezia species being involved in the same clinical presentation, and/or different genetic types of Malassezia species with different antifungal profile may colonize the same host.6,162 Despite the variable MIC data according to the protocol used, evidence exists that these yeasts have a low susceptibility to FLZ and VOR. In addition, the recent finding that efflux pump inhibitors, such as haloperidol (HAL) and pro-methazine (PTZ), display a synergistic interaction with FLZ and/or VOR only in Malassezia strains with high azole MIC values (i.e., FLZ MIC ≥ 128 μg/ml for M. furfur, FLZ MIC ≥ 64 μg/ml for M. pachydermatis and VOR MIC ≥ 4 μg/ml in both Malassezia spp.) suggests that the efflux pump genes might be overexpressed in the above strains, eventually resulting in azole resistance phenomena.163 Also the biofilm formation previously demonstrated for both M. pachydermatis and M. furfur might contribute to the low azole susceptibilities of these yeast species.164,165 The in vivo efficacy of these antifungal agents needs to be further evaluated by assessing the correlation between MICs and clinical outcomes. Only two studies reported high MIC values for azoles, that is, FLZ and POS, with unsuccessful treatment and/or prophylaxis,71,136 but these results need to be validated in multicentre studies in order to promptly develop therapeutic guidelines. Discussion The genus Malassezia comprises a heterogeneous group of species, and several species comprise multiple genotypes. These species/genotypes are specifically associated with mammalian hosts, but by using culture-independent techniques they were also retrieved from much wider-spread habitats, including various terrestrial and marine ecosystems and even deep-sea sediments. To date most studies dealing with the ecology and clinical occurrence of Malassezia are culture-based and provide us with strains suitable for genetic and phenotypic studies. On the other hand, culture-based methods have limitations and may not accurately represent the role of Malassezia species in the microbiome, ecology, or pathology due to their slow and fastidious growth and the fact that culturing conditions may not accurately represent the complexity of the natural habitat. Only in recent years, culture-independent approaches have been applied, adding valuable insights to the presence, abundance and the role of Malassezia spp. in various ecosystems. In order to understand the full potential of these new non–culture-based approaches it is important to be aware of their limitations and challenges. In general, with modern and sensitive community-analysis approaches, methodology variation has a huge impact, stressing the need for method standardization to allow meaningful future comparisons. Body sites vary in their physical and physiological composition166 potentially requiring unique sampling approaches to accurately collect microbial communities. Malassezia species have a rigorous cell wall, thus requiring a more stringent DNA-extraction method when compared to many other microorganisms. Other important downstream variables are PCR-primer design and (genome) sequence data availability. Finally, inclusion of proper controls is needed to correct for potential contamination, including fungal DNA-contamination of commercially available PCR reagents.167 Twenty years after the first landmark elucidation of the species status in Malassezia,29 a still pending question is whether the diversity found on human skin reflects on pathophysiologic associations of so-called pathogenic species with all or any of the different Malassezia-related disorders PV, D/SD, and AD. We suggest that the delineation of this question does not lay on the identification of culprit pathogenic species, but rather on the characterization of the metabolic impact of mixed Malassezia skin communities comprising the many genotypes that colonize each individual. The application of recently developed gene-deletion tools and model systems addressing different levels of immunological status will be necessary to study the role of specific genes in the pathogenesis of Malassezia. Now that transformation and genetic engineering of Malassezia has been made possible,117,168 it is likely that the roles of these and other genes and pathways in pathogenicity will be clarified. For the moment, it is important to be aware that the genus Malassezia comprises a heterogeneous group of species consisting of different genotypes that might cause the same pathologies. Moreover, these species and genotypes may vary in their susceptibility to different antifungal agents. In particular, the low susceptibility to FLZ or VOR should be considered when a long term or prophylactic therapy is implemented. Since maintenance therapy is essential for the successful management of relapsing skin disorders and infections, studies on alternative drugs should be encouraged. Whole-genome sequencing of Malassezia biodiversity enabling detailed analysis of the biochemical mechanisms involved in the adaptation to skin may pave the road to future therapeutic drug design. Declaration of Interest G.G., D.B. have received Research Grants to perform relevant work by Johnson and Johnson, Procter & Gamble and L’Oreal. T.D. is a former employee of the Procter & Gamble Co. The authors are responsible for the content and the writing of the paper. References 1. Gemmer CM, DeAngelis YM, Theelen B, Boekhout T, Dawson TL. Fast, noninvasive method for molecular detection and differentiation of Malassezia yeast species on human skin and application of the method to dandruff microbiology. J Clin Microbiol . 2002; 40: 3350– 3357. Google Scholar CrossRef Search ADS PubMed  2. Findley K, Oh J, Yang J et al.   Topographic diversity of fungal and bacterial communities in human skin. Nature . 2013; 498: 367– 370. Google Scholar CrossRef Search ADS PubMed  3. Oh J, Byrd AL, Deming C et al.   Biogeography and individuality shape function in the human skin metagenome. Nature . 2014; 514: 59– 64. Google Scholar CrossRef Search ADS PubMed  4. Prohic A, Jovovic Sadikovic T, Krupalija-Fazlic M, Kuskunovic-Vlahovljak S. Malassezia species in healthy skin and in dermatological conditions. Int J Dermatol . 2016; 55: 494– 504. Google Scholar CrossRef Search ADS PubMed  5. Iatta R, Cafarchia C, Cuna T et al.   Bloodstream infections by Malassezia and Candida species in critical care patients. Med Mycol . 2014; 52: 264– 269. Google Scholar CrossRef Search ADS PubMed  6. Velegraki A, Cafarchia C, Gaitanis G, Iatta R, Boekhout T. Malassezia infections in humans and animals: pathophysiology, detection, and treatment. PLoS Pathog . 2015; 11: e1004523. Google Scholar CrossRef Search ADS PubMed  7. Wang QM, Theelen B, Groenewald M, Bai FY, Boekhout T. Moniliellomycetes and Malasseziomycetes, two new classes in Ustilaginomycotina. Persoonia . 2014; 33: 41– 47. Google Scholar CrossRef Search ADS PubMed  8. Wu G, Zhao H, Li C et al.   Genus-wide comparative genomics of Malassezia delineates its phylogeny, physiology, and niche adaptation on human skin. PLoS Genet . 2015; 11 e1005614. Google Scholar CrossRef Search ADS PubMed  9. Boekhout T, Mayser P, Guého-Kellermann E, Velegraki A, eds. Malassezia and the Skin , 1st edn. Berlin: Springer; 2010. Google Scholar CrossRef Search ADS   10. Castellá G, Coutinho SDA, Cabañes FJ. Phylogenetic relationships of Malassezia species based on multilocus sequence analysis. Med Mycol . 2014; 52: 99– 105. Google Scholar PubMed  11. Cabanes FJ, Acqua SD, Puig L, Bragulat MR, Castellá G. New lipid-dependent Malassezia species from parrots. Rev Iberoam Micol . 2016; 33: 92– 99. Google Scholar CrossRef Search ADS PubMed  12. Honnavar P, Prasad GS, Ghosh A, Dogra S, Handa S, Rudramurthy SM. Malassezia arunalokei sp. nov., a novel yeast species isolated from seborrhoeic dermatitis patients and healthy individuals from India. J Clin Microbiol . 2016; 54: 1826– 1834 Google Scholar CrossRef Search ADS PubMed  13. Gupta AK. Molecular identification of Malassezia species by amplified fragment length polymorphism (AFLP) and sequence analyses of the internal transcribed spacer (ITS) and large subunit (LSU) regions of ribosomal DNA. J Am Acad Dermatol . 2004; 50: 106. Google Scholar CrossRef Search ADS   14. Cafarchia C, Gasser RB, Figueredo LA, Latrofa MS, Otranto D. Advances in the identification of Malassezia. Mol Cell Probes.  2011; 25: 1– 7. Google Scholar CrossRef Search ADS PubMed  15. Kolecka A, Khayhan K, Arabatzis M et al.   Efficient identification of Malassezia yeasts by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Br J Dermatol . 2014; 170: 332– 341. Google Scholar CrossRef Search ADS PubMed  16. Ilahi A, Hadrich I, Neji S, Trabelsi H, Makni F, Ayadi A. Real-Time PCR identification of six Malassezia species. Curr Microbiol . 2017; 74: 671– 677. Google Scholar CrossRef Search ADS PubMed  17. Vuran E, Karaarslan A, Karasartova D, Turegun B, Sahin F. Identification of Malassezia species from pityriasis versicolor lesions with a new multiplex PCR Method. Mycopathologia . 2014; 177: 41– 49. Google Scholar CrossRef Search ADS PubMed  18. Denis J, Machouart M, Morio F et al.   Performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identifying clinical Malassezia Isolates. J Clin Microbiol . 2017; 55: 90– 96. Google Scholar CrossRef Search ADS PubMed  19. Leung MHY, Chan KCK, Lee PKH. Skin fungal community and its correlation with bacterial community of urban Chinese individuals. Microbiome . 2016; 4: 46. Google Scholar CrossRef Search ADS PubMed  20. Akaza N, Akamatsu H, Sasaki Y et al.   Cutaneous Malassezia microbiota of healthy subjects differ by sex, body part and season. J Dermatol . 2010; 37: 786– 792. Google Scholar CrossRef Search ADS PubMed  21. Nagata R, Nagano H, Ogishima D, Nakamura Y, Hiruma M, Sugita T. Transmission of the major skin microbiota, Malassezia, from mother to neonate. Pediatr Int . 2012; 54: 350– 355. Google Scholar CrossRef Search ADS PubMed  22. Jo JH, Deming C, Kennedy EA et al.   Diverse human skin fungal communities in children converge in adulthood. J Invest Dermatol . 2016; 136: 2356– 2363. Google Scholar CrossRef Search ADS PubMed  23. Findley K, Grice EA. The skin microbiome: a focus on pathogens and their association with skin disease. PLoS Pathog . 2014; 10: e1004436. Google Scholar CrossRef Search ADS PubMed  24. Sugita T, Yamazaki T, Yamada S et al.   Temporal changes in the skin Malassezia microbiota of members of the Japanese Antarctic Research Expedition (JARE): A case study in Antarctica as a pseudo-space environment. Med Mycol . 2015; 53: 717– 724. Google Scholar CrossRef Search ADS PubMed  25. Sugita T, Yamazaki T, Makimura K et al.   Comprehensive analysis of the skin fungal microbiota of astronauts during a half-year stay at the International Space Station. Med Mycol . 2016; 54: 232– 239. Google Scholar CrossRef Search ADS PubMed  26. Gupta AK, Batra R, Bluhm R, Boekhout T, Dawson TL. Skin diseases associated with Malassezia species. J Am Acad Dermatol . 2004; 51: 785– 798. Google Scholar CrossRef Search ADS PubMed  27. Guého-Kellermann E, Boekhout T, Begerow D. Malassezia and the skin: science and clinical practice. In: Boekhout T, Mayser P, Guého-Kellermann E, Velegraki A, eds. Malassezia and the Skin , 1st edn. Berlin: Springer; 2010: 17– 63. 28. Tanaka A, Cho O, Saito M, Tsubol R, Kurakado S, Sugita T. Molecular characterization of the skin fungal microbiota in patients with seborrheic dermatitis. J Clin Exp Dermatol Res . 2014; 5: 5– 8. 29. Guého E, Midgley G, Guillot J. The genus Malassezia with description of four new species. Antonie Van Leeuwenhoek . 1996; 69: 337– 355. Google Scholar CrossRef Search ADS PubMed  30. Crespo-Erchiga V, Florencio VD. Malassezia yeasts and pityriasis versicolor. Curr Opin Infect Dis . 2006; 19: 139– 147. Google Scholar CrossRef Search ADS PubMed  31. Aspiroz C, Moreno LA, Rezusta A, Rubio C. Differentiation of three biotypes of Malassezia species on human normal skin.: correspondence with M. globosa, M. sympodialis and M. restricta. Mycopathologia . 1999; 145: 69– 74. Google Scholar CrossRef Search ADS PubMed  32. Nakabayashi A, Sei Y, Guillot J. Identification of Malassezia species isolated from patients with seborrhoeic dermatitis, atopic dermatitis, pityriasis versicolor and normal subjects. Med Mycol . 2000; 38: 337– 341. Google Scholar CrossRef Search ADS PubMed  33. Gaitanis G, Velegraki A, Alexopoulos EC, Chasapi V, Tsigonia A, Katsambas A. Distribution of Malassezia species in pityriasis versicolor and seborrhoeic dermatitis in Greece: typing of the major pityriasis versicolor isolate M. globosa. Br J Dermatol . 2006; 154: 854– 859 Google Scholar CrossRef Search ADS PubMed  34. Gupta AK, Kohli Y, Summerbell RC, Faergemann J. Quantitative culture of Malassezia species from different body sites of individuals with or without dermatoses. Med Mycol . 2001; 39: 243– 251. Google Scholar CrossRef Search ADS PubMed  35. Batra R, Boekhout T, Guého E, Cabañes FJ, Dawson TL, Gupta AK. Malassezia Baillon, emerging clinical yeasts. FEMS Yeast Res . 2005; 5: 1101– 1113. Google Scholar CrossRef Search ADS PubMed  36. Sugita T, Tajima M, Tsubuku H, Tsuboi R, Nishikawa A. Quantitative analysis of cutaneous Malassezia in atopic dermatitis patients using real-time PCR. Microbiol Immunol . 2006; 50: 549– 552. Google Scholar CrossRef Search ADS PubMed  37. Clavaud C, Jourdain R, Bar-Hen A et al.   Dandruff Is associated with disequilibrium in the proportion of the major bacterial and fungal populations colonizing the scalp. PLoS One . 2013; 8: e58203 Google Scholar CrossRef Search ADS PubMed  38. Simmons RB, Gueho E. A new species of Malassezia. Mycol Res . 1990; 94: 1146– 1149. Google Scholar CrossRef Search ADS   39. Guillot J, Guého E. The diversity of Malassezia yeasts confirmed by rRNA sequence and nuclear DNA comparisons. Antonie Van Leeuwenhoek . 1995; 67: 297– 314. Google Scholar CrossRef Search ADS PubMed  40. Bond R, Howell SA, Haywood PJ, Lloyd DH. Isolation of Malassezia sympodialis and Malassezia globosa from healthy pet cats. Vet Rec . 1997; 141: 200– 201. Google Scholar CrossRef Search ADS PubMed  41. Crespo Erchiga V, Ojeda Martos AA, Vera Casaño A, Crespo Erchiga A, Sánchez Fajardo F. Isolation and identification of Malassezia spp. In pytiriasis versicolor, seborrheic dermatitis and healthy skin. Rev Iberoam Micol . 1999; 16: S16– 21. Google Scholar PubMed  42. Aguirre C, Euliarte C, Finquelievich J, Sosa M de los Á, Giusiano G. Fungemia and interstitial lung compromise caused by Malassezia sympodialis in a pediatric patient. Rev Iberoam Micol . 2015; 32: 118– 121. Google Scholar CrossRef Search ADS PubMed  43. Patron RL. A 34-year-old man with cough, lung nodules, fever, and eosinophilia. Clin Infect Dis . 2016; 63: 1525– 1526 Google Scholar CrossRef Search ADS PubMed  44. Cabañes FJ, Theelen B, Castellá G, Boekhout T. Two new lipid-dependent Malassezia species from domestic animals. FEMS Yeast Res . 2007; 7: 1064– 1076. Google Scholar CrossRef Search ADS PubMed  45. Sugita T, Takashima M, Shinoda T et al.   New yeast species, Malassezia dermatis, isolated from patients with atopic dermatitis. 2002; 40: 1363– 1367. 46. Brooks R, Brown L. Systemic infection with Malassezia furfur in an adult receiving long-term hyperalimentation therapy. J Infect Dis . 1987; 156: 410– 411. Google Scholar CrossRef Search ADS PubMed  47. Dankner WM, Spector SA, Fierer J, Davis CE. Malassezia fungemia in neonates and adults: complication of hyperalimentation. Rev Infect Dis . 1987; 9: 743– 753. Google Scholar CrossRef Search ADS PubMed  48. Richet HM, McNeil MM, Edwards MC, Jarvis WR. Cluster of Malassezia furfur pulmonary infections in infants in a neonatal intensive-care unit. J Clin Microbiol . 1989; 27: 1197– 1200. Google Scholar PubMed  49. Surmont I, Gavilanes A, Vandepitte J, Devlieger H, Eggermont E. Malassezia furfur fungaemia in infants receiving intravenous lipid emulsions: a rarity or just underestimated? Eur J Pediatr . 1989; 148: 435– 438. Google Scholar CrossRef Search ADS PubMed  50. Weiss SJ, Schoch PE, Cunha BA. Malassezia furfur fungemia associated with central venous catheter lipid emulsion infusion. Heart Lung . 1991; 20: 87– 90. Google Scholar PubMed  51. Boekhout T, Bosboom RW. Karyotyping of Malassezia yeasts: taxonomic and epidemiological implications. Syst Appl Microbiol . 1994; 17: 146– 153. Google Scholar CrossRef Search ADS   52. Kaneko T, Murotani M, Ohkusu K, Sugita T, Makimura K. Genetic and biological features of catheter-associated Malassezia furfur from hospitalized adults. Med Mycol . 2012; 50: 74– 80. Google Scholar CrossRef Search ADS PubMed  53. Bell LM, Alpert G, Slight PH et al.   Malassezia furfur Skin colonization in infancy. Infect Control Hosp Epidemiol . 1988; 9: 151– 153. Google Scholar CrossRef Search ADS PubMed  54. Gupta P, Chakrabarti A, Singhi S, Kumar P, Honnavar P, Rudramurthy SM. Skin colonization by Malassezia spp. in hospitalized neonates and infants in a tertiary care centre in North India. Mycopathologia . 2014; 178: 267– 272. Google Scholar CrossRef Search ADS PubMed  55. Theelen B, Silvestri M, Guého E, van Belkum A, Boekhout T. Identification and typing of Malassezia yeasts using amplified fragment length polymorphism (AFLP), random amplified polymorphic DNA (RAPD) and denaturing gradient gel electrophoresis (DGGE). FEMS Yeast Res . 2001; 1: 79– 86. Google Scholar CrossRef Search ADS PubMed  56. Gupta AK, Boekhout T, Theelen B, Summerbell R, Batra R. Identification and typing of Malassezia species by amplified fragment length polymorphism and sequence analyses of the internal transcribed spacer and large-subunit regions of ribosomal DNA. J Clin Microbiol . 2004; 42: 4253– 4260. Google Scholar CrossRef Search ADS PubMed  57. Sugita T, Takashima M, Kodama M, Tsuboi R, Nishikawa A. Description of a new yeast species, Malassezia japonica, and its detection in patients with atopic dermatitis and healthy subjects. Society . 2003; 41: 4695– 4699. 58. Crespo MJ, Abarca ML, Cabañes FJ. Atypical lipid-dependent Malassezia species isolated from dogs with otitis externa. J Clin Microbiol . 2000; 38: 2383– 2385. Google Scholar PubMed  59. Crespo MJ, Abarca ML, Cabañes FJ. Occurrence of Malassezia spp. in the external ear canals of dogs and cats with and without otitis externa. Med Mycol . 2002; 40: 115– 121. Google Scholar CrossRef Search ADS PubMed  60. Jung WH, Croll D, Cho JH, Kim YR, Lee YW. Analysis of the nasal vestibule mycobiome in patients with allergic rhinitis. Mycoses . 2015; 58: 167– 172. Google Scholar CrossRef Search ADS PubMed  61. Sugita T, Tajima M, Takashima M et al.   A new yeast, Malassezia yamatoensis, isolated from a patient with seborrheic dermatitis, and its distribution in patients and healthy subjects. Microbiol Immunol . 2004; 48: 579– 583. Google Scholar CrossRef Search ADS PubMed  62. van Woerden HC, Gregory C, Brown R, Marchesi JR, Hoogendoorn B, Matthews IP. Differences in fungi present in induced sputum samples from asthma patients and non-atopic controls: a community based case control study. BMC Infect Dis . 2013; 13: 69. Google Scholar CrossRef Search ADS PubMed  63. Gueho E, Simmons RB, Pruitt WR, Meyer SA, Ahearn DG. Association of Malassezia pachydermatis with systemic infections of humans. J Clin Microbiol . 1987; 25: 1789– 1790. Google Scholar PubMed  64. Larocco M, Dorenbaum A, Robinson A, Pickering LK. Recovery of Malassezia pachydermatis from eight infants in a neonatal intensive care nursery: clinical and laboratory features. Pediatr Infect Dis J . 1988; 7: 398– 401. Google Scholar CrossRef Search ADS PubMed  65. Mickelsen PA, Viano-Paulson MC, Stevens DA, Diaz PS. Clinical and microbiological features of infection with Malassezia pachydermatis in high-risk infants. J Infect Dis . 1988; 157: 1163– 1168. Google Scholar CrossRef Search ADS PubMed  66. van Belkum A Boekhout T, Bosboom R. Monitoring spread of Malassezia infections in a neonatal intensive care unit by PCR-mediated genetic typing. J Clin Microbiol . 1994; 32: 2528– 2532. Google Scholar PubMed  67. Guého E, Boekhout T, Ashbee HR, Guillot J, Van Belkum A, Faergemann J. The role of Malassezia species in the ecology of human skin and as pathogens. Med Mycol . 1998; 36: 220– 229. Google Scholar PubMed  68. Chang HJ, Miller HL, Watkins N et al.   An epidemic of Malassezia pachydermatis in an intensive care nursery associated with colonization of health care workers’ pet dogs. N Engl J Med . 1998; 338: 706– 711. Google Scholar CrossRef Search ADS PubMed  69. Lautenbach E, Nachamkin I, Schuster MG. Malassezia pachydermatis infections. N Engl J Med . 1998; 339: 270. Google Scholar CrossRef Search ADS PubMed  70. Chryssanthou E, Broberger U, Petrini B. Malassezia pachydermatis fungaemia in a neonatal intensive care unit. Acta Paediatr . 2001; 90: 323– 327. Google Scholar CrossRef Search ADS PubMed  71. Choudhury S, Marte RL. Malassezia pachydermatis fungaemia in an adult on posaconazole prophylaxis for acute myeloid leukaemia. Pathology . 2014; 46: 466– 467. Google Scholar CrossRef Search ADS PubMed  72. Roman J, Bagla P, Ren P, Blanton LS, Berman MA. Malassezia pachydermatis fungemia in an adult with multibacillary leprosy. Med Mycol Case Rep . 2016; 12: 1– 3. Google Scholar CrossRef Search ADS PubMed  73. Prohic A, Kasumagic-Halilovic E. Identification of Malassezia pachydermatis from healthy and diseased human skin. Med Arh . 2009; 63: 317– 319. Google Scholar PubMed  74. Morris DO, O’Shea K, Shofer FS, Rankin S. Malassezia pachydermatis carriage in dog owners. Emerg Infect Dis . 2005; 11: 83– 88. Google Scholar CrossRef Search ADS PubMed  75. Gaitanis G, Magiatis P, Stathopoulou K et al.   AhR ligands, malassezin, and indolo[3,2-b]carbazole are selectively produced by Malassezia furfur strains isolated from seborrheic dermatitis. J Invest Dermatol . 2008; 128: 1620– 1625. Google Scholar CrossRef Search ADS PubMed  76. Gaitanis G, Velegraki A, Magiatis P, Pappas P, Bassukas ID. Could Malassezia yeasts be implicated in skin carcinogenesis through the production of aryl-hydrocarbon receptor ligands? Med Hypotheses . 2011; 77: 47– 51. Google Scholar CrossRef Search ADS PubMed  77. Chng KR, Tay ASL, Li C et al.   Whole metagenome profiling reveals skin microbiome-dependent susceptibility to atopic dermatitis flare. Nat Microbiol . 2016; 1: 16106. Google Scholar CrossRef Search ADS PubMed  78. Cleland EJ, Bassiouni A, Boase S, Dowd S, Vreugde S, Womald PJ. The fungal microbiome in chronic rhinosinusitis: richness, diversity, postoperative changes and patient outcomes. Int Forum Allergy Rhinol . 2014; 4: 259– 265. Google Scholar CrossRef Search ADS PubMed  79. Gelber JT, Cope EK, Goldberg AN, Pletcher SD. Evaluation of Malassezia and Common Fungal Pathogens in Subtypes of Chronic Rhinosinusitis. Int Forum Allergy Rhinol . 2016; 6: 950– 955. Google Scholar CrossRef Search ADS PubMed  80. Dupuy AK, David MS, Li L et al.   Redefining the human oral mycobiome with improved practices in amplicon-based taxonomy: discovery of Malassezia as a prominent commensal. PLoS One . 2014; 9: e90899. Google Scholar CrossRef Search ADS PubMed  81. Ghannoum MA, Jurevic RJ, Mukherjee PK et al.   Characterization of the oral fungal microbiome (mycobiome) in healthy individuals. PLoS Pathog . 2010; 6: e1000713. Google Scholar CrossRef Search ADS PubMed  82. Diaz PI, Hong B-Y, Dupuy AK, Strausbaugh LD. Mining the oral mycobiome: Methods, components, and meaning. Virulence . 2017; 8: 313– 323. Google Scholar CrossRef Search ADS PubMed  83. Shelburne SA, Ajami NJ, Chibucos MC et al.   Implementation of a pan-genomic approach to investigate holobiont-infecting microbe interaction: a case report of a leukemic patient with invasive mucormycosis. PLoS One . 2015; 10: e0139851. Google Scholar CrossRef Search ADS PubMed  84. Persoon IF, Buijs MJ, Özok AR et al.   The mycobiome of root canal infections is correlated to the bacteriome. Clin Oral Investig . 2017; 21: 1871– 1881. Google Scholar CrossRef Search ADS PubMed  85. Delhaes L, Monchy S, Fréalle E et al.   The airway microbiota in cystic fibrosis: a complex fungal and bacterial community—implications for therapeutic management. PLoS One . 2012; 7: e36313. Google Scholar CrossRef Search ADS PubMed  86. Willger SD, Grim SL, Dolben EL et al.   Characterization and quantification of the fungal microbiome in serial samples from individuals with cystic fibrosis. Microbiome . 2014; 2: 40. Google Scholar CrossRef Search ADS PubMed  87. Gouba N, Raoult D, Drancourt M. Eukaryote culturomics of the gut reveals new species. PLoS One . 2014; 9: e106994. Google Scholar CrossRef Search ADS PubMed  88. Suhr MJ, Hallen-Adams HE. The human gut mycobiome: pitfalls and potentials-a mycologist's perspective. Mycologia . 2015; 107: 1057– 1073. Google Scholar CrossRef Search ADS PubMed  89. Strati F, Di Paola M, Stefanini I et al.   Age and gender affect the composition of fungal population of the human gastrointestinal tract. Front Microbiol . 2016; 7: 1227. Google Scholar CrossRef Search ADS PubMed  90. Hallen-Adams HE, Suhr MJ. Fungi in the healthy human gastrointestinal tract. Virulence . 2017; 8: 352– 358. Google Scholar CrossRef Search ADS PubMed  91. Bond R. Superficial veterinary mycoses. Clin Dermatol . 2010; 28: 226– 236. Google Scholar CrossRef Search ADS PubMed  92. Sugita T, Boekhout T, Velegraki A, Guillot J, Hađina S, Cabañes FJ. Epidemiology of Malassezia-related skin infections. In: Boekhout T, Mayser P, Guého-Kellermann E, Velegraki A, eds. Malassezia and the Skin , 1st edn. Berlin: Springer; 2010: 65– 119. 93. Cabañes FJ. Malassezia yeasts: how many species infect humans and animals? PLoS Pathog . 2014; 10: e1003892. Google Scholar CrossRef Search ADS PubMed  94. Guillot J, Guého E, Chévrier G, Chermette R. Epidemiological analysis of Malassezia pachydermatis isolates by partial sequencing of the large subunit ribosomal RNA. Res Vet Sci . 1997; 62: 22– 25. Google Scholar CrossRef Search ADS PubMed  95. Puig L, Castellá G, Cabañes FJ. Cryptic diversity of Malassezia pachydermatis from healthy and diseased domestic animals. Mycopathologia . 2016; 181: 681– 688. Google Scholar CrossRef Search ADS PubMed  96. Shokri H, Khosravi AR. An epidemiological study of animals dermatomycoses in Iran. J Mycol Med . 2016; 26: 170– 177. Google Scholar CrossRef Search ADS PubMed  97. Hirai A, Kano R, Makimura K et al.   Malassezia nana sp. nov., a novel lipid-dependent yeast species isolated from animals. Int J Syst Evol Microbiol . 2004; 54: 623– 627. Google Scholar CrossRef Search ADS PubMed  98. Castellá G, De Bellis F Bond R, Cabañes FJ. Molecular characterization of Malassezia nana isolates from cats. Vet Microbiol . 2011; 148: 363– 367. Google Scholar CrossRef Search ADS PubMed  99. Aldrovandi AL, Osugui L, Acqua Coutinho SD. Is Malassezia nana the main species in horses’ ear canal microbiome? Braz J Microbiol . 2016; 47: 770– 774. Google Scholar CrossRef Search ADS PubMed  100. Duarte ER, Batista RD, Hahn RC, Hamdan JS. Factors associated with the prevalence of Malassezia species in the external ears of cattle from the state of Minas Gerais, Brazil. Med Mycol . 2003; 41: 137– 142. Google Scholar PubMed  101. Shokri H. Occurrence and distribution of Malassezia species on skin and external ear canal of horses. Mycoses . 2016; 59: 28– 33. Google Scholar CrossRef Search ADS PubMed  102. Richards TA, Jones MDM, Leonard G, Bass D. Marine fungi: their ecology and molecular diversity. Ann Rev Mar Sci . 2012; 4: 495– 522. Google Scholar CrossRef Search ADS PubMed  103. Amend A. From dandruff to deep-sea vents: Malassezia-like fungi are ecologically hyper-diverse. PLoS Pathog . 2014; 10: e1004277. Google Scholar CrossRef Search ADS PubMed  104. Elhady A, Giné A, Topalovic O et al.   Microbiomes associated with infective stages of root-knot and lesion nematodes in soil. PLoS One . 2017; 12: e0177145. Google Scholar CrossRef Search ADS PubMed  105. Quandt A, Glasco A, James T. Intestinal mycobiome variation across geography and phylogeny in the snail genus Conus. In: 29th Fungal Genetics Conference Asilomar . Vol Asilomar: Genetics Society of America; 2017: 20. 106. Renker C, Alphei J, Buscot F. Soil nematodes associated with the mammal pathogenic fungal genus Malassezia (Basidiomycota: Ustilaginomycetes) in Central European forests. Biol Fertil Soils . 2003; 37: 70– 72. 107. Duarte ER, Resende JC, Rosa CA, Hamdan JS. Prevalence of yeasts and mycelial fungi in bovine parasitic otitis in the state of Minas Gerais, Brazil. J Vet Med B Infect Dis Vet Public Health . 2001; 48: 631– 635. Google Scholar CrossRef Search ADS PubMed  108. Malacrinò A, Schena L, Campolo O et al.   A metabarcoding survey on the fungal microbiota associated to the olive fruit fly. Microb Ecol . 2017; 73: 677– 684. Google Scholar CrossRef Search ADS PubMed  109. Zhu Y, Engström PG, Tellgren-Roth C et al.   Proteogenomics produces comprehensive and highly accurate protein-coding gene annotation in a complete genome assembly of Malassezia sympodialis. Nucleic Acids Res . 2017; 45: 2629– 2643 Google Scholar PubMed  110. Triana S, Ohm RA, De Cock H, Restrepo S, Celis A. Draft genome sequence of the animal and human pathogen Malassezia pachydermatis strain CBS 1879. Genome Announc . 2015; 3: 5– 6. Google Scholar CrossRef Search ADS   111. Xu J, Saunders CW, Hu P et al.   Dandruff-associated Malassezia genomes reveal convergent and divergent virulence traits shared with plant and human fungal pathogens. Proc Natl Acad Sci U S A . 2007; 104: 18730– 18735. Google Scholar CrossRef Search ADS PubMed  112. Saunders CW, Scheynius A, Heitman J. Malassezia fungi are specialized to live on skin and associated with dandruff, eczema, and other skin diseases. PLoS Pathog . 2012; 8: e1002701. Google Scholar CrossRef Search ADS PubMed  113. Gordon James A, Abraham KH, Cox DS, Moore AE, Pople JE. Metabolic analysis of the cutaneous fungi Malassezia globosa and M. restricta for insights on scalp condition and dandruff. Int J Cosmet Sci . 2013; 35: 169– 175. Google Scholar CrossRef Search ADS PubMed  114. Wisecaver JH, Alexander WG, King SB, Hittinger CT, Rokas A. Dynamic evolution of nitric oxide detoxifying flavohemoglobins, a family of single-protein metabolic modules in bacteria and eukaryotes. Mol Biol Evol . 2016; 33: 1979– 1987. Google Scholar CrossRef Search ADS PubMed  115. Nielsen K, Heitman J. Sex and virulence of human pathogenic fungi. Dunlap JC, ed. Adv Genet . 2007; 57: 143– 173. Google Scholar CrossRef Search ADS   116. Heitman J, Carter DA, Dyer PS, Soll DR. Sexual reproduction of human fungal pathogens. Cold Spring Harb Perspect Med . 2014; 4: a019281. Google Scholar CrossRef Search ADS   117. Ianiri G, Averette A, Kingsbury JM, Heitman J, Idnurm A. Gene function analysis in the ubiquitous human commensal and pathogen Malassezia genus. MBio . 2016; 7: e01853. Google Scholar CrossRef Search ADS PubMed  118. Boekhout T, Kamp M, Guého E. Molecular typing of Malassezia species with PFGE and RAPD. Med Mycol . 1998; 36: 365– 372. Google Scholar CrossRef Search ADS PubMed  119. DeAngelis YM, Gemmer CM, Kaczvinsky JR, Kenneally DC, Schwartz JR, Dawson TL. Three etiologic facets of dandruff and seborrheic dermatitis: Malassezia fungi, sebaceous lipids, and individual sensitivity. J Investig Dermatol Symp Proc . 2005; 10: 295– 297. Google Scholar CrossRef Search ADS PubMed  120. Gaitanis G, Velegraki A, Mayser P, Bassukas ID. Skin diseases associated with Malassezia yeasts: facts and controversies. Clin Dermatol . 2013; 31: 455– 463. Google Scholar CrossRef Search ADS PubMed  121. Gupta AK, Bluhm R, Summerbell R. Pityriasis versicolor. J Eur Acad Dermatol Venereol . 2002; 16: 19– 33. Google Scholar CrossRef Search ADS PubMed  122. Saadatzadeh MR, Ashbee HR, Holland KT, Ingham E. Production of the mycelial phase of Malassezia in vitro. Med Mycol . 2001; 39: 487– 493. Google Scholar CrossRef Search ADS PubMed  123. Lee WJ, Kim JY, Song CH et al.   Disruption of barrier function in dermatophytosis and pityriasis versicolor. J Dermatol . 2011; 38: 1049– 1053. Google Scholar CrossRef Search ADS PubMed  124. Larangeira de Almeida H, Mayser P. Absence of sunburn in lesions of pityriasis versicolor alba. Mycoses . 2006; 49: 516– 516. Google Scholar CrossRef Search ADS PubMed  125. Mittermann I, Wikberg G, Johansson C et al.   IgE sensitization profiles differ between adult patients with severe and moderate atopic dermatitis. PLoS One . 2016; 11: e0156077. Google Scholar CrossRef Search ADS PubMed  126. Ishii K, Hiragun M, Hiragun T et al.   A human monoclonal IgE antibody that binds to MGL_1304, a major allergen in human sweat, without activation of mast cells and basophils. Biochem Biophys Res Commun . 2015; 468: 99– 104. Google Scholar CrossRef Search ADS PubMed  127. Hiragun M, Hiragun T, Ishii K et al.   Elevated serum IgE against MGL_1304 in patients with atopic dermatitis and cholinergic urticaria. Allergol Int . 2014; 63: 83– 93. Google Scholar CrossRef Search ADS PubMed  128. Gaitanis G, Magiatis P, Hantschke M, Bassukas ID, Velegraki A. The Malassezia genus in skin and systemic diseases. Clin Microbiol Rev . 2012; 25: 106– 141. Google Scholar CrossRef Search ADS PubMed  129. Jourdain R, Moga A, Vingler P et al.   Exploration of scalp surface lipids reveals squalene peroxide as a potential actor in dandruff condition. Arch Dermatol Res . 2016; 308: 153– 163. Google Scholar CrossRef Search ADS PubMed  130. Magiatis P, Pappas P, Gaitanis G et al.   Malassezia yeasts produce a collection of exceptionally potent activators of the Ah (dioxin) receptor detected in diseased human skin. J Invest Dermatol . 2013; 133: 2023– 2030. Google Scholar CrossRef Search ADS PubMed  131. Vlachos C, Gaitanis G, Alexopoulos EC, Papadopoulou C, Bassukas ID. Phospholipase activity after β-endorphin exposure discriminates Malassezia strains isolated from healthy and seborrhoeic dermatitis skin. J Eur Acad Dermatology Venereol . 2013; 27: 1575– 1578. Google Scholar CrossRef Search ADS   132. Hald M, Arendrup MC, Svejgaard EL et al.   Evidence-based Danish guidelines for the treatment of Malassezia-related skin diseases. Acta Derm Venereol . 2015; 95: 12– 19. Google Scholar CrossRef Search ADS PubMed  133. Negre A, Bensignor E, Guillot J. Evidence-based veterinary dermatology: a systematic review of interventions for Malassezia dermatitis in dogs. Vet Dermatol . 2009; 20: 1– 12. Google Scholar CrossRef Search ADS PubMed  134. Jesus FPK, Lautert C, Zanette RA et al.   In vitro susceptibility of fluconazole-susceptible and -resistant isolates of Malassezia pachydermatis against azoles. Vet Microbiol . 2011; 152: 161– 164. Google Scholar CrossRef Search ADS PubMed  135. Cafarchia C, Figueredo LA, Favuzzi V et al.   Assessment of the antifungal susceptibility of Malassezia pachydermatis in various media using a CLSI protocol. Vet Microbiol . 2012; 159: 536– 540. Google Scholar CrossRef Search ADS PubMed  136. Iatta R, Figueredo LA, Montagna MT, Otranto D, Cafarchia C. In vitro antifungal susceptibility of Malassezia furfur from bloodstream infections. J Med Microbiol . 2014; 63: 1467– 1473. Google Scholar CrossRef Search ADS PubMed  137. Gupta A, Foley K. Antifungal treatment for pityriasis versicolor. J Fungi . 2015; 1: 13– 29. Google Scholar CrossRef Search ADS   138. Arendrup MC, Boekhout T, Akova M et al.   ESCMID and ECMM joint clinical guidelines for the diagnosis and management of rare invasive yeast infections. Clin Microbiol Infect . 2014; 20: 76– 98. Google Scholar CrossRef Search ADS PubMed  139. Nakamura Y, Kano R, Murai T, Watanabe S, Hasegawa A. Susceptibility testing of Malassezia species using the urea broth microdilution method. Antimicrob Agents Chemother . 2000; 44: 2185– 2186. Google Scholar CrossRef Search ADS PubMed  140. Rincon S, Cepero de Garcia MC, Espinel-Ingroff A. A Modified Christensen's urea and CLSI broth microdilution method for testing susceptibilities of six Malassezia species to voriconazole, itraconazole, and ketoconazole. J Clin Microbiol . 2006; 44: 3429– 3431. Google Scholar CrossRef Search ADS PubMed  141. Yurayart C, Nuchnoul N, Moolkum P et al.   Antifungal agent susceptibilities and interpretation of Malassezia pachydermatis and Candida parapsilosis isolated from dogs with and without seborrheic dermatitis skin. Med Mycol . 2013; 51: 721– 730. Google Scholar CrossRef Search ADS PubMed  142. Carrillo-Muñoz AJ, Rojas F, Tur-Tur C et al.   In vitro antifungal activity of topical and systemic antifungal drugs against Malassezia species. Mycoses . 2013; 56: 571– 575. Google Scholar CrossRef Search ADS PubMed  143. Rojas FD, Sosa M d. l. A, Fernandez MS, Cattana ME, Cordoba SB, Giusiano GE. Antifungal susceptibility of Malassezia furfur, Malassezia sympodialis, and Malassezia globosa to azole drugs and amphotericin B evaluated using a broth microdilution method. Med Mycol . 2014; 52: 641– 646. Google Scholar CrossRef Search ADS PubMed  144. Velegraki A, Alexopoulos EC, Kritikou S, Gaitanis G. Use of fatty acid RPMI 1640 media for testing susceptibilities of eight Malassezia species to the new triazole posaconazole and to six established antifungal agents by a modified NCCLS M27-A2 microdilution method and Etest. J Clin Microbiol . 2004; 42: 3589– 3593. Google Scholar CrossRef Search ADS PubMed  145. Álvarez-Pérez S, García ME, Peláez T, Blanco JL. Genotyping and antifungal susceptibility testing of multiple Malassezia pachydermatis isolates from otitis and dermatitis cases in pets: is it really worth the effort? Med Mycol . 2016; 54: 72– 79. Google Scholar PubMed  146. Peano A, Pasquetti M, Chiavassa E. Superficial mycoses in dogs and cats. Summa Anim da Compagnia . 2012; 4: 40– 55 [Micosi superficiali del cane e del gatto]. 147. Breu F, Guggenbichler S, Wollmann J. Superficial Mycoses in Dogs and Cats . Worcestershire: NCAPP; 2011. 148. Ahman S, Perrins N, Bond R. Treatment of Malassezia pachydermatis-associated seborrhoeic dermatitis in Devon Rex cats with itraconazole—a pilot study. Vet Dermatol . 2007; 18: 171– 174. Google Scholar CrossRef Search ADS PubMed  149. Berger DJ, Lewis TP, Schick AE, Stone RT. Comparison of once-daily versus twice-weekly terbinafine administration for the treatment of canine Malassezia dermatitis—a pilot study. Vet Dermatol . 2012; 23: 418– e479. Google Scholar CrossRef Search ADS PubMed  150. Gupta AK, Bluhm R. Seborrheic dermatitis. J Eur Acad Dermatol Venereol . 2004; 18: 13– 26. Google Scholar CrossRef Search ADS PubMed  151. Tragiannidis A, Bisping G, Koehler G, Groll AH. Minireview: Malassezia infections in immunocompromised patients. Mycoses . 2010; 53: 187– 195. Google Scholar CrossRef Search ADS PubMed  152. Cafarchia C, Iatta R, Immediato D, Puttilli MR, Otranto D. Azole susceptibility of Malassezia pachydermatis and Malassezia furfur and tentative epidemiological cut-off values. Med Mycol . 2015; 53: 743– 748. Google Scholar CrossRef Search ADS PubMed  153. Rojas FD, Córdoba SB, de Los Ángeles Sosa M et al.   Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies. Mycoses . 2017; 60: 104– 111. Google Scholar CrossRef Search ADS PubMed  154. Leong C, Buttafuoco A, Glatz M, Bosshard PP. Antifungal susceptibility testing of Malassezia spp. with an optimized colorimetric broth microdilution method. J Clin Microbiol . 2017; 55: 1883– 1893. Google Scholar CrossRef Search ADS PubMed  155. Miranda KC, de Araujo CR, Costa CR, Passos XS, de Fátima Lisboa Fernandes O, do Rosário Rodrigues Silva M. Antifungal activities of azole agents against the Malassezia species. Int J Antimicrob Agents . 2007; 29: 281– 284. Google Scholar CrossRef Search ADS PubMed  156. Rodriguez-Tudela JL, Alcazar-Fuoli L, Mellado E, Alastruey-Izquierdo A, Monzon A, Cuenca-Estrella M. Epidemiological Cutoffs and Cross-Resistance to Azole Drugs in Aspergillus fumigatus. Antimicrob Agents Chemother . 2008; 52: 2468– 2472. Google Scholar CrossRef Search ADS PubMed  157. Pfaller MA, Diekema DJ. Progress in antifungal susceptibility testing of Candida spp. by use of clinical and laboratory standards institute broth microdilution methods, 2010 to 2012. J Clin Microbiol . 2012; 50: 2846– 2856. Google Scholar CrossRef Search ADS PubMed  158. Álvarez-Pérez S, Blanco JL, Peláez T, Cutuli M, García ME. In vitro amphotericin B susceptibility of Malassezia pachydermatis determined by the CLSI broth microdilution method and Etest using lipid-enriched media. Antimicrob Agents Chemother . 2014; 58: 4203– 4206. Google Scholar CrossRef Search ADS PubMed  159. Iatta R, Immediato D, Montagna MT, Otranto D, Cafarchia C. In vitro activity of two amphotericin B formulations against Malassezia furfur strains recovered from patients with bloodstream infections. Med Mycol . 2015; 53: 269– 274. Google Scholar CrossRef Search ADS PubMed  160. Mitsuyama J, Nomura N, Hashimoto K et al.   In vitro and in vivo antifungal activities of T-2307, a novel arylamidine. Antimicrob Agents Chemother . 2008; 52: 1318– 1324. Google Scholar CrossRef Search ADS PubMed  161. Fera MT, La Camera E, De Sarro A. New triazoles and echinocandins: mode of action, in vitro activity and mechanisms of resistance. Expert Rev Anti Infect Ther . 2009; 7: 981– 998. Google Scholar CrossRef Search ADS PubMed  162. Prohic A, KuskunovicVlahovljak S, Sadikovic T, Cavaljuga S. The Prevalence and species composition of Malassezia yeasts in patients with clinically suspected onychomycosis. Med Arch . 2015; 69: 81. Google Scholar CrossRef Search ADS PubMed  163. Iatta R, Puttilli MR, Immediato D, Otranto D, Cafarchia C. The role of drug efflux pumps in Malassezia pachydermatis and Malassezia furfur defence against azoles. Mycoses . 2016; 60: 178– 182. Google Scholar CrossRef Search ADS PubMed  164. Figueredo LA, Cafarchia C, Otranto D. Antifungal susceptibility of Malassezia pachydermatis biofilm. Med Mycol . 2013; 51: 863– 867. Google Scholar CrossRef Search ADS PubMed  165. Angiolella L, Leone C, Rojas F, Mussin J, de los Angeles Sosa M, Giusiano G. Biofilm, adherence, and hydrophobicity as virulence factors in Malassezia furfur. Med Mycol . March 2017. 166. Sanmiguel A, Grice EA. Interactions between host factors and the skin microbiome. Cell Mol Life Sci . 2015; 72: 1499– 1515. Google Scholar CrossRef Search ADS PubMed  167. Czurda S, Smelik S, Preuner-Stix S, Nogueira F, Lion T. Occurrence of fungal DNA contamination in PCR reagents: approaches to control and decontamination. J Clin Microbiol . 2016; 54: 148– 152. Google Scholar CrossRef Search ADS PubMed  168. Celis AM, Vos AM, Triana S et al.   Highly efficient transformation system for Malassezia furfur and Malassezia pachydermatis using Agrobacterium tumefaciens-mediated transformation. J Microbiol Methods . 2017; 134: 1– 6. Google Scholar CrossRef Search ADS PubMed  169. Kumar S, Stecher G, Tamura K. MEGA7: Molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol Biol Evol . 2016; 33: 1870– 1874. Google Scholar CrossRef Search ADS PubMed  170. Al-Sweih N, Ahmad S, Joseph L, Khan S, Khan Z. Malassezia pachydermatis fungemia in a preterm neonate resistant to fluconazole and flucytosine. Med Mycol Case Rep . 2014; 5: 9– 11. Google Scholar CrossRef Search ADS PubMed  171. Oliveri S, Trovato L, Betta P, Romeo MG, Nicoletti G. Malassezia furfur fungaemia in a neonatal patient detected by lysis-centrifugation blood culture method: first case reported in Italy. Mycoses . 2011; 54: e638– 640. Google Scholar CrossRef Search ADS PubMed  172. Chu CM, Lai RW. Malassezia furfur fungaemia in a ventilator-dependent patient without known risk factors. Hong Kong Med J . 2002; 8: 212– 214. Google Scholar PubMed  173. Barber GR, Brown AE, Kiehn TE, Edwards FF, Armstrong D. Catheter-related Malassezia furfur fungemia in immunocompromised patients. Am J Med . 1993; 95: 365– 370. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Journal

Medical MycologyOxford University Press

Published: Apr 1, 2018

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off