Open Forum Infectious Diseases CORRESPONDENCE Keratitis due to an Unusual In the present study, we report a second the right eye showed an attached retina Pathogenic Social Amoeba, case of keratitis by D. polycephalu.m with an echo-free vitreous cavity. At the Dictyostelium polycephalum A 15-year-old, non–contact lens wearer time of the visit, the patient was using To the Editor—Infections with patho- presented with a 20-day history of prick-0.5% moxifloxacin eye drops installed genic free-living amoeba including ing sensation, redness, swelling, pain, 5×/d. Corneal scrapings were collected Acanthamoeba spp., Naegleria fowleri, and watering in the right eye aer ft injury using a sterile surgical blade (#15 on a Balamuthia mandrillaris, and Sappinia with a fingernail. The right eye showed lid bard parker handle) under topical anes- pedata have been documented in many edema, the conjunctiva was congested, and thesia. Corneal scrapings were subjected countries . However, social amoeba the cornea showed a large epithelial defectto dir ect microscopic examination and have not been reported earlier as etio- with a whitish yellow infiltrate meas -ur inoculated onto blood agar, brain-heart logical agents in human infections. In ing 10 × 10 mm involving almost all the infusion broth, Sabourauds dextrose agar, April 2010, we reported a case of keratitis cornea (Figure 1A). Visual acuity was and non-nutrient agar (NNA). in an immunocompetent person by social expressed as the ability to see hand move- e dir Th ect microscopic examination of amoeba, Dictyostelium polycephalum . ments near the face. Ultrasonography ofco rneal scraping revealed double-walled AF BC DE Figure 1. (A) Cornea of the patient’s right eye showing whitish yellow infiltrate. (B) Spherical cysts morphologically resembling Dictyostelium species in Gram stain. (C) Unicellular myxamoeba of Dictyostelium on non-nutrient agar. (D) Cell streaming, wheel-shaped aggregates of myxamoeba of Dictyostelium. (E) Pseudo plasmodia (slug) of Dictyostelium. (F) Corneal graft of the patient at the last follow-up. CORRESPONDENCE • OFID • 1 Downloaded from https://academic.oup.com/ofid/article-abstract/5/2/ofy009/4810328 by Ed 'DeepDyve' Gillespie user on 16 March 2018 cysts morphologically resembling e m Th orphological identification of the Acknowledgments Financial support. None. Dictyostelium species in potassium hy- organism was confirmed by sequencing. Study on human subjects. e p Th rocedures droxide mount, Gram stain (Figure 1B), At the last follow-up (4 months aer t ft he followed in the study were in accordance with the and Giemsa stain. Based on direct mi- surgery), the corneal graft of the patient ethical standards of Helsinki declaration and the croscopy findings, a presumptive diag- was clear (Figure 1F), with no evidence patient written consent obtained. Potential conifl cts of interest. All authors: nosis of Dictyostelium keratitis was made. of infection, and the best corrected visual no reported conflicts of interest. All authors As the size of the infiltrate was too large acuity was expressed as 6/9. have submitted the ICMJE Form for Disclosure to treat medically and no data on anti- e lif Th e cycle of Dictyostelium is of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the microbial susceptibility of Dictyostelium unique, and the transition from unicel- manuscript have been disclosed. were available, surgical treatment was lular organism to multicellular fruiting advised. Penetrating keratoplasty was body is seen during the life cycle . e Th 1 2 Arjun Srirampur, Ashok Kumar Reddy, 3 4 performed instead of lamellar kerato-vegetative stage of Dictyostelium species Swathi Siva, and Anupama Kalwad plasty as the infiltrate had penetrated is a free-living myxamoeba. When the Consultant Ophthalmologist, Anand Eye Institute, Hyderabad, India; Consultant Microbiologist, GHR Micro the descemet’s membrane and there was food becomes scarce, the myxamoeba Diagnostics, Hyderabad, India; Cornea and Anterior Segment a small endoexudate in the visual axis. aggregates to form a slug or pseudo plas- Services, Anand Eye Institute, Hyderabad, India; Cornea and Anterior Segment Services, Anand Eye Institute, Hyderabad, Postoperatively, the patient was treate md odium. The slug forms a fruiting body. India with topical 1% prednisolone acetate eye Under some conditions, some myxam- drops every 2 hours and 0.5% moxifloxa- oeba enter into an encystment stage, References cin eye drops every 2 hours. Aer ft a week, termed a microcyst. The sexual life cycle 1. Visveswara GS. Infections with free living amoebae. the antibiotic was stopped, and steroid of Dictyostelium species involves the Handb Clin Neurol 2013; 114:153–68. 2. Reddy AK, Balne PK, Garg P, et al. Dictyostelium eye drops tapered gradually. formation of macrocysts. Instead of the polycephalum infection of human cornea. Emerg Several unicellular myxamoeba myxamoeba forming a slug, two of the Infect Dis 2010; 16:1644–5. 3. Tsvetkova N, Schild M, Panaiotov S, et al. The (Figure 1C), cell streaming, wheel-shaped aggregating amoebae fuse, consume the identification of free-living environmental isolates aggregates of myxamoeba (Figure 1D), remaining cells, and form a macrocyst of amoebae from Bulgaria. Parasitol Res 2004; pseudo plasmodia (slugs) (Figure 1E), and [5, 6]. There are more than 100 species 92:405–13. 4. Schaap P. Evolutionary crossroads in developmen- spherical cysts were seen aer 48 h ft ours of of Dictyostelium identified so far . It is tal biology: Dictyostelium discoideum . Development incubation on an NNA plate inoculated quite surprising that in both the cases of 2011; 138:387–96. 5. Romeralo M, Cavender JC, Landolt JC, et al. with corneal scraping. Fruiting bodiesD ictyostelium keratitis the species iden- An expanded phylogeny of social amoebas or Sorocorps that are very small, typit -ified is polycephalum. Dictyostelium (Dictyostelia) shows increasing diversity and new morphological patterns. BMC Evol Biol 2011; cally clustered to form coremiform fruc-species are found in arctic, tropical, des- 11:84. tifications, and variable in number were ert, and rain forest soils . There are a 6. Blaskovics JC, Raper KB. Encystment stages of dic- tyostelium. Biol Bull 1957; 113:58–88. observed on NNA plates aer 5 ft days of number of ecological changes that oer ff incubation. Based on morphology, the opportunities for existing nonpathogenic organism was identified as Dictyostelium organisms to become pathogenic and Received 27 September 2017; editorial decision 28 polycephalum. e co Th rneal button inoc- adapt to the human body. A fingernail December 2017; accepted 13 January 2018. ulated onto the NNA plate showedco ntaminated with soil may be the source Correspondence: A. K. Reddy, PhD, D(ABMM), FCCM, GHR Micro Diagnostics, Dwarakapuri Colony, Panjagutta, the growth of Dictyostelium . DNA was of infection in the present patient. Hyderabad-500082, India. Email: firstname.lastname@example.org. extracted from the growth on the NNA e c Th linical presentation is similar in Open Forum Infectious Diseases plate, inoculated with corneal scrapingst he 2 cases, except for the presence of © The Author(s) 2018. Published by Oxford University Press and directly from the corneal button. The endoexudates in the visual axis in the on behalf of Infectious Diseases Society of America. This is an Open Access article distributed under the terms of the extracted DNA was subjected to 18S rDNAs econd patient. Both the patients were Creative Commons Attribution-NonCommercial-NoDerivs li- polymerase chain reaction (PCR) for treated by surgery. However, there is cence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution free-living amoebas . 3 e Th PCR product a need to study the antimicrobial sus- of the work, in any medium, provided the original work is not was subjected to bidirectional sequencing, ceptibility of this emerging pathogenic altered or transformed in any way, and that the work is prop- erly cited. For commercial re-use, please contact journals. and the sequence is deposited at GenBank organism for the medical management of email@example.com (GenBank accession number MF780724). patients. DOI: 10.1093/ofid/ofy009 2 • OFID • CORRESPONDENCE Downloaded from https://academic.oup.com/ofid/article-abstract/5/2/ofy009/4810328 by Ed 'DeepDyve' Gillespie user on 16 March 2018
Open Forum Infectious Diseases – Oxford University Press
Published: Feb 1, 2018
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