Microbial Spectrum of Intra-Abdominal Abscesses in Perforating Crohn’s Disease: Results from a Prospective German Registry

Microbial Spectrum of Intra-Abdominal Abscesses in Perforating Crohn’s Disease: Results from a... Abstract Background Intra-abdominal abscesses [IAAs] are common life-threatening complications in patients with Crohn’s disease [CD]. In addition to interventional drainage and surgical therapy, empirical antibiotic therapy represents a cornerstone of treatment, but contemporary data on microbial spectra and antimicrobial resistance are scarce. Methods We recruited 105 patients with CD and IAAs from nine German centres for a prospective registry in order to characterize the microbiological spectrum, resistance profiles, antibiotic therapy and outcome. Results In 92 of 105 patients, microbial investigations of abscess material revealed pathogenic microorganisms. A total of 174 pathogens were isolated, with a median of 2 pathogens per culture [range: 1–6]. Most frequently isolated pathogens were E. coli [45 patients], Streptococcus spp. [28 patients], Enterococci [27 patients], Candida [13 patients] and anaerobes [12 patients]. Resistance to third-generation cephalosporins, penicillins with beta-lactamase inhibitors and quinolones were observed in 51, 36 and 35 patients, respectively. Seven patients had multiple-drug-resistant bacteria. Thirty patients received inadequate empirical treatment, and this was more frequent in patients receiving steroids or immunosuppression [37%] than in patients without immunosuppression [10%: p = 0.001] and was associated with a longer hospital stay [21 days vs 13 days, p = 0.003]. Conclusion Based on antimicrobial resistance profiles, we herein report a high rate of inadequate empirical first-line therapy for IAAs in CD, especially in patients receiving immunosuppression, and this is associated with prolonged hospitalization. Microbial spectrum, intra-abdominal abscess [IAA], perforating Crohn’s disease, antimicrobial resistance 1. Introduction Intra-abdominal abscesses [IAAs] are frequent, potentially life-threatening complications in patients with Crohn’s disease [CD], occurring in up to 18% of patients.1,2 Therapeutic strategies comprise the use of antibiotics, interventional drainage and surgery. Owing to a lack of prospective studies, current treatment concepts are based on retrospective data and case series, and favour a combination of antibiotic therapy and percutaneous drainage, followed by delayed surgical therapy if necessary.3–8 Known risk factors for the failure of non-surgical therapeutic concepts are abscess size, ongoing immunosuppression or steroid medication and fistulating disease.2–4,9 For intra-abdominal infections [IAI], the selection of empirical antibiotic therapy should be based on local epidemiology, individual patient risk factors for difficult-to-treat pathogens, and the clinical severity of infection.10 Comparable with patients without CD,11,12 the major pathogens causing IAAs are autochthonous colonic flora and comprise E. coli, Streptococcus spp., Enterococcus spp. and anaerobes as major identified organisms.2,13 However, recent studies also show an alarming increase in quinolone-resistant E. coli,13 intrinsic 3GC-resistant Enterococcus faecium14 and Candida spp.15 in CD patients at risk from centres in Asia and North America. As prospective data on the microbiological spectrum and antibiotic resistance for Germany are missing, we implemented a prospective multicenter registry in order to characterize the microbial spectrum, antibiotic resistance and risk factors for therapy failure in CD patients with IAAs. 2. Methods 2.1. Study design To characterize the pathogen spectrum and resistance patterns, patients with CD, who underwent microbiological sampling of IAAs were prospectively included from nine German university and non-university centres between March 2013 and July 2016. Pus from IAAs was obtained either by percutaneous puncture guided by ultrasound or computed tomography [CT] or during surgical procedures. Microbial cultures were obtained, processed and analysed according to local standard procedures. Data were prospectively collected using an electronic CRF system [OpenClinica]. The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the internal review board [local ethics committee; 3783-05/13]. 2.2. Definition of multiple-drug resistance Gram-negative bacteria were defined as multidrug-resistant if they were non-susceptible to at least one agent in at least three antimicrobial categories [MDR] and non-susceptible to at least 1 agent in all but two or fewer categories [XDR] according to the interim definition of the European Centre for Disease Prevention and Control [ECDC] and the Centers for Disease Control and Prevention [CDC].16 Furthermore, methicillin-resistant Staphylococcus aureus [MRSA] and vancomycin-resistant Enterococcus spp. [VRE] were defined as multidrug resistant bacteria. 2.3 Statistical analysis Statistical analyses were performed using SPSS 20 [IBM Inc., Armonk, New York, USA]. Statistical differences were performed using the non-parametric Mann–Whitney U test, Kruskal–Wallis test for comparison of continuous data, or Fisher’s exact test for discrete variables, as appropriate. The significance level in two-sided testing was p < 0.05 without correction for multiple testing. Data are given as absolute number and percentage or as median with first and third quartiles. 3. Results A total of 105 consecutive patients with IAAs due to CD were prospectively studied between March 2013 and July 2016. Patients had a median age of 32 years and presented with a median disease history of CD of 6 years [range: 0 to 49 years]. Thirty-six per cent of patients had isolated ileal disease, 26% had colonic disease and 36% had ileocolonic disease, and 40 [38%] patients had undergone previous CD-related surgery [Table 1]. Overall, 40 [38.1%] patients received steroids [16 as a monotherapy and 24 in combination with immunosuppressants] and 27 [25.7%] patients received steroid-free immunosuppression [16 thiopurines, 7 anti-TNF therapy, 4 combo therapy]. Age, sex and smoking status were not associated with microbial spectra or resistance profiles. Table 1. Baseline characteristics. Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Data are presented as absolute numbers or as median and first and third quartiles. Abbreviations: IAA,intra-abdominal abscess; HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitor. View Large Table 1. Baseline characteristics. Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Data are presented as absolute numbers or as median and first and third quartiles. Abbreviations: IAA,intra-abdominal abscess; HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitor. View Large 3.1. Isolated pathogens In 13 [12.4%] patients, abscess cultures were sterile. In the remaining 92 patients, a total of 174 pathogens could be isolated, with a median of 2 pathogens per culture [range: 1–6]. The most frequently isolated gram-negative pathogens were Enterobacteriaceae comprising E. coli in 45 patients [25.9% of pathogens; 32.1% of patients], Klebsiella spp. in 9 patients [5.4% of pathogens; 5.7% of patients] and Proteus spp. in 5 patients [3.0% of pathogens, 4.8% of patients]. The most frequently isolated gram-positive pathogens were Streptococcus spp. in 33 isolations in 27 patients [19.0% of pathogens; 25.7% of patients] and Enterococcus spp. isolated in 28 isolations [22 E. faecium, 6 E. faecalis] in 27 patients [16.1% of pathogens; 25.7% of patients]. Staphylococci were detected in 10 patients [6.0% of pathogens; 9.5% of patients], with 4 of them being Staphylococcus aureus. Anaerobes were detected in 12 patients [7.2% of pathogens; 11.4% of patients]. Fungi were detected in 13 patients [8.0% of pathogens; 13.2% of patients], comprising Candida albicans in 9 patients, non-albicans Candida spp. in 3 patients, and mixed albicans/non-albicans in 1 patient. The antimicrobial profiles stratified for the immunosuppressive therapy are shown in Supplementary Table 1. There was no association between microbiological results and the source of microbiological samples [p = 0.300, detailed data not shown]. 3.2. Impact of immunosuppression on the microbial spectrum and antimicrobial resistance patterns Gram-negative infection was significantly more frequent in patients receiving steroids [65.0%] compared with in patients without immunosuppression [29.2%] or non-steroidal immunosuppression [40.7%, p = 0.020] [Table 2]. In particular, quinolone-resistant E. coli were more frequently isolated from patients receiving steroids [20.0%], compared with patients with steroid-free immunosuppression [7.4%] or without immunosuppression [2.1%; p = 0.035]. There were no differences in the frequencies of enterococcal or fungal IAAs with respect to the type of immunosuppression [Table 2] or to whether patients received mono as compared with combination therapy [data not shown]. Fungal infections were not associated with immunosuppressive therapy [p = 0.265]. Table 2. Differences in microbial spectrum and resistance with respect to immunosuppressive therapy. Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Data are presented as absolute numbers and percentage. Abbreviations: ESBL, extended-spectrum beta lactamase; VRE, vancomycin-resistant Enterococcus spp.; MDR, multidrug-resistant. View Large Table 2. Differences in microbial spectrum and resistance with respect to immunosuppressive therapy. Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Data are presented as absolute numbers and percentage. Abbreviations: ESBL, extended-spectrum beta lactamase; VRE, vancomycin-resistant Enterococcus spp.; MDR, multidrug-resistant. View Large Out of 92 patients with positive IAA culture results, data on microbial resistance were reported from 82 patients. Overall, 7 patients presented with MDR bacteria (1 MRSA, 3 multi-resistant gram-negative [MRGN], 3 VRE), without significant differences with respect to current immunosuppression [Table 2]. Antimicrobial resistance against quinolones was observed in 35 patients [fungal pathogens in 13 patients, 1 Staphylococcus, 9 Levofloxacin-resistant Enterococci, 11 E. coli, 3 other Enterobacteriacae] and against broad-spectrum penicillins with beta-lactamase inhibitors [BLIs] in 36 patients (fungal pathogens in 13 patients, ampicillin-resistant enterococci in 13 patients, 3 staphylococci [including 1 MRSA], 9 E. coli including 5 ESBL-producing strains, 4 ESBL-producing Enterobacteriaceae and 2 other bacteria). Antimicrobial resistance against third-generation cephalosporins [3GCs] was observed in 51 patients [fungal pathogens in 13 patients, enterococci in 27 patients, staphylococci including MRSA in 5 patients, ESBL-producing gram negatives in 9 patients, non-ESBL gram negatives in 5 patients and other bacteria in 3 patients]. Ongoing antibiotic therapy before microbiological sampling was not associated with higher rates of antibiotic resistance to the three antibiotic classes [Table 3]. Indicators of resistance against quinolones and broad-spectrum penicillins were higher white blood cell count, whereas resistance against 3GCs was more often observed in patients with lower C-reactive protein levels [Table 3]. Patients with microorganisms resistant to 3GCs more often had colonic or ileocolonic in contrast to ileal manifestation [Table 3]. Fistulas were described in 58 [55.2%] patients [56 internal, 2 external, 3 patients with both internal and external], without any differences between microbiological spectra or antimicrobial resistance between different origins of fistulas. Fungal infections were more frequently found in nosocomial IAAs [57.1% v. 13.5%, p=0.024]. Table 3. Risk factors for non-susceptible antibiotic therapy. Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Data are presented as absolute numbers or as median and first and third quartiles; p-values refer to susceptible isolates of the same antibiotic class. Abbreviations: HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitors. View Large Table 3. Risk factors for non-susceptible antibiotic therapy. Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Data are presented as absolute numbers or as median and first and third quartiles; p-values refer to susceptible isolates of the same antibiotic class. Abbreviations: HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitors. View Large 3.3. Treatment regimens Overall, 86 patients received empirical antibiotic therapy, comprising 42 with monotherapy and 44 with combination therapy. It was started before sampling in 73 patients. Broad-spectrum penicillins were used in in 41 patients [47.7%], 3GCs in 21 patients [24.4%], quinolones in 19 patients [22.1%], carbapenems in 3 patients and tigecyclin in 1 patient. Empirical antibiotic therapy combination with metronidazole was used in 28 patients [26 as combination therapy with 3GCs or quinolones]. The complete antimicrobial resistance profile was available in 83 out of 86 patients treated with antibiotics. In 53 patients, isolated pathogens were fully susceptible to empirical antibiotic therapy, whereas antimicrobial resistance to empirical therapy was observed in 30 patients. Antibiotic regimens associated with non-susceptible pathogens were penicillin-based in 14 patients, 3GC-based regimens in 9 patients, quinolone-based in 6 patients, and monotherapy with linezolid in one patient. Administration of antibiotics before microbiological sampling showed a trend towards, but was not significantly associated with, sterile culture results [p = 0.081]. Fungi were not more frequently isolated in patients receiving antibiotics before sampling [16.4% vs 10.0%, p = 1.000] Culture findings of microorganisms with antimicrobial resistance leading to change in empirically chosen antibiotic treatment were Candida spp. in 8 patients, Enterococcus spp. in 11 patients [9 E. faecium, 2 E. faecalis], gram-negative Enterobacteriacae in 15 patients [4 ESBL, 12 quinolone-resistant], Staphylococci in 5 patients, Streptococci in 2 patients and anaerobes in 4 patients. 3.4. Outcome Based on the in vitro resistance profiles, empirical antibiotic therapy was inadequate more often in patients receiving steroids or immunosuppression [37%] than in patients without immunosuppression [10%: p = 0.001] [Table 2]. Immunosuppression was discontinued in 49.3%, continued with reduced dosing in 13.4% and continued unchanged in 34.3% of the patients. Patients treated with inadequate empiric antibiotic therapy had a significantly longer hospital stay compared with patients receiving adequate empiric antibiotic therapy [median 21 days [interquartiles 15–25] vs 13 days [interquartiles 9–20], p = 0.003], although median treatment duration did not differ [12 vs 10 days; p = 0.14]. 4. Discussion Current epidemiological data on IAAs in CD are mostly based on small cases series or retrospective monocentric data,2,13,15 and data from large prospective studies are missing. In this German prospective multicenter registry of CD patients with IAAs, we report a high rate of inadequate antimicrobial empirical first-line therapy based on obtained antimicrobial resistance profiles. Inadequate therapy was more often observed in patients receiving immunosuppressive therapy and was associated with longer hospital stay, indicating clinical relevance. It is important to note that in this cohort, in which the vast majority of patients were treated with immunosuppressants, we could not find an increased overall risk of MDR in patients treated with steroids, thiopurines or anti-TNF. Only elevated white blood cell count was associated an increased probability for quinolone or penicillin/BLI resistance. Colonic or ileocolonic disease was associated with an increased probability for 3GC-resistant pathogens. Due to lack of robust data on microbiological patterns in abscesses in Crohn’s disease, antibiotics are often selected on the basis of data on microbiological patterns in other IAI. However, there can be relevant differences in microbial spectrum in IAI based on the underlying disease. In the current study, the most frequent pathogens was E. coli, followed by Streptococcus spp. In contrast, in Reuken et al., the most frequent pathogens isolated from primary peritonitis in patients with liver cirrhosis were Enterococci,17 requiring a different antibiotic therapy. Another retrospective study described Candida spp. in 51.9% of all IAI in intensive care patients,18 whereas it was only isolated in 13.2% of the patients in the current study. The lack of robust microbiological data on pathogens in CD-associated IAAs resulted in a broad variety of antibiotic regimens in our study. Overall, 20 different antibiotic combinations were used. Antibiotic resistance is an emerging problem also in IAI,19,20 and ciprofloxacin resistance in up to two-thirds of gram-negative isolates in patients with Crohn’s diseases in a retrospective study from Korea.13 Inadequate empirical therapy was associated with a longer hospital stay [21 vs 13 days], which is in line with reported outcomes for IAI from our group21 and others,22–25 and which translates into increased mortality and costs.17,24–26 The association of white blood cell count with resistance to quinolones and broad-spectrum penicillins with BLI may help to improve future antibiotic regimens. However, there are many potential confounders of this association, underlining the need for prospective evaluation. Especially, immunosuppressive medication with prednisolone is known to elevate white blood cell count and was used frequently in patients included in the current register. Surgical or interventional procedures are other potential confounders. Compared with high rates of antibiotic resistance in other recent studies from Asia and North America, empirical therapy rates of MDR pathogens were rather low in our register, with only 4 MDR Enterobacteriacae.14,27 Antibiotic resistance was predominantly associated with the following factors. (i) Patients receiving immunosuppressive therapy with steroids had significantly more quinolone-resistant E. coli [20.0%]. Quinolone-resistance is an increasing problem in CD patients with IAI. In our study, quinolone-resistant Enterobacteriacae were isolated in 12 patients. Recent studies reported quinolone-resistance in up to two-thirds of gram-negative isolates13 in CD patients, and other studies reported high rates of quinolone resistance in IAI.11,28–30 Increasing rates of resistance are challenging the use of quinolones as first-line therapy in IAI in patients at risk, such as those with nosocomial acquisition, with previous quinolone therapy, or under steroid therapy10; these categories of patients were also identified in our study as being at risk of quinolone-resistant E. coli infections. (ii) The second factor associated with high rates of antibiotic resistance is the frequent isolation of pathogens, which are per se resistant against one class of antibiotics, such as enterococci against cephalosporins or fungi against antibiotics. Recent studies found high rates of enterococcal-associated IAI11,17 that were associated with an increase in mortality in patients suffering from acute pancreatitis31 or spontaneous bacterial peritonitis.17 Our study could not identify risk factors for infection with Enterococcus spp. in CD patients, but resistance against 3GCs was associated with colonic localization of the CD and lower CRP levels. Other risk factors associated with intra-abdominal enterococcal infections are a history of antibiotic therapy,17 nosocomial acquisition and immunosuppression.17,32,33 The second pathogen accounting for a high rate of non-susceptible therapy is Candida spp., which was isolated in 13 patients in our study [12.4%]. Other studies reported Candida in up to 28.9% of IAI in intensive care units,34 with higher rates occurring when the origin of the intra-abdominal infection is in the upper-gastrointestinal tract due to normal colonization.10,35 Intra-abdominal Candida infection is associated with a poor prognosis in patients with nosocomial acquisition36 and mortality can reach up to 48% in these patients. Other risk factors associated with mortality in Candida infection are high APACHE II Score, respiratory failure or origin of the infection from the upper gastrointestinal tract.37 Delayed antifungal therapy is known to be associated with an increase in mortality.38,39 Contrasting these facts, the calculated antifungal therapy was zero percent in our registry, despite the isolation of Candida spp. in 12.4% of the 105 patients included. Therefore, antifungal therapy has to be taken into account when choosing antimicrobial therapy in CD patients with IAAs. Current therapeutic concepts for the management of IAA in CD consist of the combination of antibiotic therapy and interventional or percutaneous drainage followed by surgical therapy if necessary.3–8 The optimum time-point for delayed surgery still has to be defined. Some authors suggest 6–8 weeks,40 whereas others recommend only 2–3 weeks.41 Percutaneous drainage can avoid surgical therapy in up to 30% of patients,3,42 and a small study could not find differences in primary outcome when comparing patients undergoing surgical therapy with those receiving antibiotic therapy only,15 but patients receiving antibiotic therapy alone had a high recurrence rate of 29%. A recent meta-analysis did not find significant differences between percutaneous and surgical drainage with respect to length of hospital stay, stoma requirement or post-procedural complications.42 Contrasting that, inadequate antibiotic therapy pre-operative is associated with an increased risk of septic complications (occurring in up to 30% of these patients) and an increased number of patients requiring a stoma.43 In order to optimize therapeutic concepts dealing with antibiotic therapy alone without surgical therapy and for the pre-operative management of CD patients with IAAs, knowledge of the antibiotic-resistance pattern is crucial for therapeutic success; therefore, microbiological sampling should be performed in order to detect resistant pathogens and to optimize antibiotic therapy. To our knowledge, this is the first prospective, multicentre register evaluating microbiological patterns and resistances in patients suffering from CD in Germany, and may therefore serve as a basis for optimizing antibiotic regimens in selection of antibiotic substances. Quinolones should not be used in patients treated with steroids or when local resistance data indicates high rates of quinolone-resistant Enterococci. Funding None declared. Conflict of Interest No author reported any conflict of interests relevant to the reported article. Author Contributions All authors participated in patient inclusion and data collection. PAR and TB performed statistical analyses and wrote the paper, AS designed the study. All authors approved the final version of the manuscript. Supplementary Data Supplementary data for this article can be found at Journal of Crohns and Colitis Online. Abbreviations. 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Google Scholar CrossRef Search ADS PubMed Copyright © 2018 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Crohn's and Colitis Oxford University Press

Microbial Spectrum of Intra-Abdominal Abscesses in Perforating Crohn’s Disease: Results from a Prospective German Registry

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Oxford University Press
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Copyright © 2018 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com
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1873-9946
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1876-4479
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10.1093/ecco-jcc/jjy017
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Abstract

Abstract Background Intra-abdominal abscesses [IAAs] are common life-threatening complications in patients with Crohn’s disease [CD]. In addition to interventional drainage and surgical therapy, empirical antibiotic therapy represents a cornerstone of treatment, but contemporary data on microbial spectra and antimicrobial resistance are scarce. Methods We recruited 105 patients with CD and IAAs from nine German centres for a prospective registry in order to characterize the microbiological spectrum, resistance profiles, antibiotic therapy and outcome. Results In 92 of 105 patients, microbial investigations of abscess material revealed pathogenic microorganisms. A total of 174 pathogens were isolated, with a median of 2 pathogens per culture [range: 1–6]. Most frequently isolated pathogens were E. coli [45 patients], Streptococcus spp. [28 patients], Enterococci [27 patients], Candida [13 patients] and anaerobes [12 patients]. Resistance to third-generation cephalosporins, penicillins with beta-lactamase inhibitors and quinolones were observed in 51, 36 and 35 patients, respectively. Seven patients had multiple-drug-resistant bacteria. Thirty patients received inadequate empirical treatment, and this was more frequent in patients receiving steroids or immunosuppression [37%] than in patients without immunosuppression [10%: p = 0.001] and was associated with a longer hospital stay [21 days vs 13 days, p = 0.003]. Conclusion Based on antimicrobial resistance profiles, we herein report a high rate of inadequate empirical first-line therapy for IAAs in CD, especially in patients receiving immunosuppression, and this is associated with prolonged hospitalization. Microbial spectrum, intra-abdominal abscess [IAA], perforating Crohn’s disease, antimicrobial resistance 1. Introduction Intra-abdominal abscesses [IAAs] are frequent, potentially life-threatening complications in patients with Crohn’s disease [CD], occurring in up to 18% of patients.1,2 Therapeutic strategies comprise the use of antibiotics, interventional drainage and surgery. Owing to a lack of prospective studies, current treatment concepts are based on retrospective data and case series, and favour a combination of antibiotic therapy and percutaneous drainage, followed by delayed surgical therapy if necessary.3–8 Known risk factors for the failure of non-surgical therapeutic concepts are abscess size, ongoing immunosuppression or steroid medication and fistulating disease.2–4,9 For intra-abdominal infections [IAI], the selection of empirical antibiotic therapy should be based on local epidemiology, individual patient risk factors for difficult-to-treat pathogens, and the clinical severity of infection.10 Comparable with patients without CD,11,12 the major pathogens causing IAAs are autochthonous colonic flora and comprise E. coli, Streptococcus spp., Enterococcus spp. and anaerobes as major identified organisms.2,13 However, recent studies also show an alarming increase in quinolone-resistant E. coli,13 intrinsic 3GC-resistant Enterococcus faecium14 and Candida spp.15 in CD patients at risk from centres in Asia and North America. As prospective data on the microbiological spectrum and antibiotic resistance for Germany are missing, we implemented a prospective multicenter registry in order to characterize the microbial spectrum, antibiotic resistance and risk factors for therapy failure in CD patients with IAAs. 2. Methods 2.1. Study design To characterize the pathogen spectrum and resistance patterns, patients with CD, who underwent microbiological sampling of IAAs were prospectively included from nine German university and non-university centres between March 2013 and July 2016. Pus from IAAs was obtained either by percutaneous puncture guided by ultrasound or computed tomography [CT] or during surgical procedures. Microbial cultures were obtained, processed and analysed according to local standard procedures. Data were prospectively collected using an electronic CRF system [OpenClinica]. The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the internal review board [local ethics committee; 3783-05/13]. 2.2. Definition of multiple-drug resistance Gram-negative bacteria were defined as multidrug-resistant if they were non-susceptible to at least one agent in at least three antimicrobial categories [MDR] and non-susceptible to at least 1 agent in all but two or fewer categories [XDR] according to the interim definition of the European Centre for Disease Prevention and Control [ECDC] and the Centers for Disease Control and Prevention [CDC].16 Furthermore, methicillin-resistant Staphylococcus aureus [MRSA] and vancomycin-resistant Enterococcus spp. [VRE] were defined as multidrug resistant bacteria. 2.3 Statistical analysis Statistical analyses were performed using SPSS 20 [IBM Inc., Armonk, New York, USA]. Statistical differences were performed using the non-parametric Mann–Whitney U test, Kruskal–Wallis test for comparison of continuous data, or Fisher’s exact test for discrete variables, as appropriate. The significance level in two-sided testing was p < 0.05 without correction for multiple testing. Data are given as absolute number and percentage or as median with first and third quartiles. 3. Results A total of 105 consecutive patients with IAAs due to CD were prospectively studied between March 2013 and July 2016. Patients had a median age of 32 years and presented with a median disease history of CD of 6 years [range: 0 to 49 years]. Thirty-six per cent of patients had isolated ileal disease, 26% had colonic disease and 36% had ileocolonic disease, and 40 [38%] patients had undergone previous CD-related surgery [Table 1]. Overall, 40 [38.1%] patients received steroids [16 as a monotherapy and 24 in combination with immunosuppressants] and 27 [25.7%] patients received steroid-free immunosuppression [16 thiopurines, 7 anti-TNF therapy, 4 combo therapy]. Age, sex and smoking status were not associated with microbial spectra or resistance profiles. Table 1. Baseline characteristics. Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Data are presented as absolute numbers or as median and first and third quartiles. Abbreviations: IAA,intra-abdominal abscess; HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitor. View Large Table 1. Baseline characteristics. Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Patients with IAA [n=105] Male sex [n] 53 [50.5%] Age [years] 32 [25; 41] Never smoked 57 [54.3%] Body mass index [kg/m2] 21.5 [17.9; 23.6] Disease history and activity Manifestation:  Ileal 49 [46.7%]  Colonic 23 [21.9%]  Ileocolonic 26 [24.8%] Duration of disease [years] 6.0 [1.0; 15.0] HBI 7 [5; 10] Fistulizing disease 58 [55.2%] Stenosing disease 52 [49.5%] Previous CD-related surgery 40 [38.1%] HBI [points] 7 [5; 10] Immunosuppressive therapy at inclusion 67 [63.8%] Steroids alone or in combination 40 [38.1] Steroid-free immunosuppression 27 [25.7%] Used immunosuppressants Prednisolone [n] 40 Anti-TNF [n] 25 Azathioprine/6-MP [n] 40 Other [n] 6 Laboratory Data White blood cells [/nL] 10.9 [8.1; 15.2] C-reactive protein [mg/L] 83.9 [27.2; 140.0] Alanine aminotransferase [µmol/L s] 0.33 [0.22; 0.45] Hemoglobin [mmol/L] 7.2 [6.1; 8.0] Platelets [/nL] 399 [315; 516] Abscess characteristics Diagnosed by ultrasound 55 [52.4%] Diagnosed by computed tomography 27 [25.7%] Diagnosed by magnetic resonance imaging 52 [49.5%] Median maximum diameter [cm] 4.1 [2.8; 6.0] Medical treatment of Crohn’s disease Immunosuppression continued 23/67 [34.3%] Immunosuppression halted/reduced 44/67 [65.7%] Antibiotic treatment 86 [81.9%] Broad-spectrum penicillins/BLI 41/86 [47.7%] Cephalosporins 21/86 [24.4%] Quinolones 19 [22.1%] Other 5 [5.8%] Empiric antibiotic treatment 82 [78.1%] Change in antibiotic therapy 27 [25.7%] Primary drainage of abscess No drainage 26 [24.8%] Surgical drainage 54 [51.4%] Percutaneous drainage 20 [19.0%] Endoscopic drainage 6 [5.7%] Data are presented as absolute numbers or as median and first and third quartiles. Abbreviations: IAA,intra-abdominal abscess; HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitor. View Large 3.1. Isolated pathogens In 13 [12.4%] patients, abscess cultures were sterile. In the remaining 92 patients, a total of 174 pathogens could be isolated, with a median of 2 pathogens per culture [range: 1–6]. The most frequently isolated gram-negative pathogens were Enterobacteriaceae comprising E. coli in 45 patients [25.9% of pathogens; 32.1% of patients], Klebsiella spp. in 9 patients [5.4% of pathogens; 5.7% of patients] and Proteus spp. in 5 patients [3.0% of pathogens, 4.8% of patients]. The most frequently isolated gram-positive pathogens were Streptococcus spp. in 33 isolations in 27 patients [19.0% of pathogens; 25.7% of patients] and Enterococcus spp. isolated in 28 isolations [22 E. faecium, 6 E. faecalis] in 27 patients [16.1% of pathogens; 25.7% of patients]. Staphylococci were detected in 10 patients [6.0% of pathogens; 9.5% of patients], with 4 of them being Staphylococcus aureus. Anaerobes were detected in 12 patients [7.2% of pathogens; 11.4% of patients]. Fungi were detected in 13 patients [8.0% of pathogens; 13.2% of patients], comprising Candida albicans in 9 patients, non-albicans Candida spp. in 3 patients, and mixed albicans/non-albicans in 1 patient. The antimicrobial profiles stratified for the immunosuppressive therapy are shown in Supplementary Table 1. There was no association between microbiological results and the source of microbiological samples [p = 0.300, detailed data not shown]. 3.2. Impact of immunosuppression on the microbial spectrum and antimicrobial resistance patterns Gram-negative infection was significantly more frequent in patients receiving steroids [65.0%] compared with in patients without immunosuppression [29.2%] or non-steroidal immunosuppression [40.7%, p = 0.020] [Table 2]. In particular, quinolone-resistant E. coli were more frequently isolated from patients receiving steroids [20.0%], compared with patients with steroid-free immunosuppression [7.4%] or without immunosuppression [2.1%; p = 0.035]. There were no differences in the frequencies of enterococcal or fungal IAAs with respect to the type of immunosuppression [Table 2] or to whether patients received mono as compared with combination therapy [data not shown]. Fungal infections were not associated with immunosuppressive therapy [p = 0.265]. Table 2. Differences in microbial spectrum and resistance with respect to immunosuppressive therapy. Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Data are presented as absolute numbers and percentage. Abbreviations: ESBL, extended-spectrum beta lactamase; VRE, vancomycin-resistant Enterococcus spp.; MDR, multidrug-resistant. View Large Table 2. Differences in microbial spectrum and resistance with respect to immunosuppressive therapy. Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Without immunosuppression [n = 48] With steroids [n = 40] With steroid-free immunosuppression [n = 27] p-value Gram negatives 14 [29.2%] 26 [65.0%] 11 [40.7%] 0.020 E. coli 12 [25.0%] 22 [55.0%] 11 [40.7%] 0.09  ESBL E. coli 0 4 [10.0%] 1 [3.7%] 0.17  Quinolone resistant 1 [2.1%] 8 [20.0%] 2 [7.4%] 0.035 Other Enterobacteriaceae 6 [12.5%] 9 [22.5%] 1 [3.7%] 0.10  ESBL 1 [2.1%] 3 [7.5%] 0 0.45  Quinolone resistant 1 [2.1%] 1 [2.5%] 1 [3.7%] 1.00 Streptococci 10 [37.0%] 13 [32.5%] 6 [22.2%] 0.65 Enterococci 9 [18.6%] 8 [20.0%] 10 [37.0%] 0.35  E. faecalis 2 [4.2%] 3 [7.5%] 1 [3.7%] 0.49  E. faecium 7 [14.6%] 6 [15.0%] 9 [33.3%]  VRE 2 [4.2%] 0 0 Anaerobes 5 [10.4%] 2 [5.0%] 4 [14.8%] 0.33 Fungi 5 [10.4%] 6 [15.0%] 2 [7.4%] 0.70 MDR pathogens 2 [4.2%] 3 [7.5%] 2 [7.4%] 1.00 Inadequate therapy 5 [10.4%] 12 [30.0%] 13 [48.1%] 0.034 Data are presented as absolute numbers and percentage. Abbreviations: ESBL, extended-spectrum beta lactamase; VRE, vancomycin-resistant Enterococcus spp.; MDR, multidrug-resistant. View Large Out of 92 patients with positive IAA culture results, data on microbial resistance were reported from 82 patients. Overall, 7 patients presented with MDR bacteria (1 MRSA, 3 multi-resistant gram-negative [MRGN], 3 VRE), without significant differences with respect to current immunosuppression [Table 2]. Antimicrobial resistance against quinolones was observed in 35 patients [fungal pathogens in 13 patients, 1 Staphylococcus, 9 Levofloxacin-resistant Enterococci, 11 E. coli, 3 other Enterobacteriacae] and against broad-spectrum penicillins with beta-lactamase inhibitors [BLIs] in 36 patients (fungal pathogens in 13 patients, ampicillin-resistant enterococci in 13 patients, 3 staphylococci [including 1 MRSA], 9 E. coli including 5 ESBL-producing strains, 4 ESBL-producing Enterobacteriaceae and 2 other bacteria). Antimicrobial resistance against third-generation cephalosporins [3GCs] was observed in 51 patients [fungal pathogens in 13 patients, enterococci in 27 patients, staphylococci including MRSA in 5 patients, ESBL-producing gram negatives in 9 patients, non-ESBL gram negatives in 5 patients and other bacteria in 3 patients]. Ongoing antibiotic therapy before microbiological sampling was not associated with higher rates of antibiotic resistance to the three antibiotic classes [Table 3]. Indicators of resistance against quinolones and broad-spectrum penicillins were higher white blood cell count, whereas resistance against 3GCs was more often observed in patients with lower C-reactive protein levels [Table 3]. Patients with microorganisms resistant to 3GCs more often had colonic or ileocolonic in contrast to ileal manifestation [Table 3]. Fistulas were described in 58 [55.2%] patients [56 internal, 2 external, 3 patients with both internal and external], without any differences between microbiological spectra or antimicrobial resistance between different origins of fistulas. Fungal infections were more frequently found in nosocomial IAAs [57.1% v. 13.5%, p=0.024]. Table 3. Risk factors for non-susceptible antibiotic therapy. Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Data are presented as absolute numbers or as median and first and third quartiles; p-values refer to susceptible isolates of the same antibiotic class. Abbreviations: HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitors. View Large Table 3. Risk factors for non-susceptible antibiotic therapy. Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Third generation cephalosporin Broad-spectrum penicillins/BLI Quinolones Susceptible [n = 32] Resistant [n = 51] p value Susceptible [n = 47] Resistant [n = 36] p value Susceptible [n = 48] Resistant [n = 35] p value Male sex 14 [43.8%] 18 [31.6%] 0.475 17 [36.2%] 15 [41.7%] 0.531 20 [41.7%] 12 [34.3%] 0.290 Age [years] 28.0 [24.5; 40.5] 33.0 [24.75; 43.75] 0.556 30.5 [24.25; 40.75] 35.5 [25.0; 47.0] 0.375 31.0 [25.0; 41.0] 35.0 [23.0; 42.0] 0.883 Body mass index 21.1 [17.8; 24.5] 20.6 [17.7; 23.8] 0.281 21.2 [17.8; 23.3] 20.3 [17.9; 24.5] 0.983 20.8 [17.9; 23.1] 21.1 [17.8; 25.1] 0.399 HBI [points] 7 [6; 9.5] 5 [6; 10] 0.880 7 [5; 9,75] 7 [4.75; 10] 0.421 7 [4.5; 10] 7 [5.5; 10] 0.333 C-reactive protein [mg/L] 96.4 [38.7; 217.8] 75.5 [24.3; 134.3] 0.042 96.4 [27.2; 149.0] 96.6 [32.8; 159.9] 0.993 92.0 [21.2; 146.0] 98.7 [53.9; 197.9] 0.277 White blood cells [/nL] 10.9 [7.0; 15.3] 10.7 [8.6; 15.2] 0.992 9.5 [6.4; 14.4] 12.4 [9.6; 18.1] 0.005 9.8 [6.9; 14.3] 12.7 [8.8; 18.4] 0.014 Ongoing antibiotic treatment 26 [81.2%] 40 [78.4%] 0.578 36 [76.6%] 30 [83.3%] 0.428 38 [79.2%] 28 [80.0%] 1.000 Colonic/ileocolonic 11 [34.4%] 31 [60.8%] 0.037 24 [51.1%] 19 [52.8%] 1.000 25 [52.1%] 18 [51.4%] 1.000 Previous CD-related surgery 12 [37.5%] 20 [35.1%] 0.815 14 [29.8%] 18 [50.0%] 0.107 18 [37.5%] 14 [40.0%] 1.000 Fistulae 20 [62.5%] 35 [68.6%] 0.818 26 [55.3%] 22 [61.1%] 1.000 28 [58.3%] 20 [57.1%] 0.645 Any immunosuppression 19 [61.3%] 34 [65.4%] 0.814 27 [42.6%] 26 [72.2%] 0.177 28 [58.3%] 25 [71.4%] 0.254 Steroids alone 5 [15.7%] 9 [17.6%] 1.000 9 [19.1%] 5 [13.9%] 0.570 6 [12.5%] 8 [22.9%] 0.246 Combination therapy 7 [21.9%] 14 [27.5%] 0.796 11 [23.4%] 10 [27.8%] 0.800 12 [25.0%] 9 [25.7%] 1.000 Prednisolone 12 [37.5%] 20 [39.2%] 1.000 19 [40.4%] 13 [36.1%] 0.821 16 [33.3%] 16 [45.7%] 0.265 Anti-TNF 7 [21.9%] 13 [25.5%] 1.000 10 [21.3%] 10 [27.8%] 0.606 10 [20.8%] 10 [28.6%] 0.446 Azathioprine 11 [34.4%] 20 [39.2%] 0.819 16 [34.0%] 15 [41.7%] 0.501 20 [41.7%] 11 [31.4%] 0.368 Data are presented as absolute numbers or as median and first and third quartiles; p-values refer to susceptible isolates of the same antibiotic class. Abbreviations: HBI, Harvey–Bradshaw index; BLI, beta-lactamase inhibitors. View Large 3.3. Treatment regimens Overall, 86 patients received empirical antibiotic therapy, comprising 42 with monotherapy and 44 with combination therapy. It was started before sampling in 73 patients. Broad-spectrum penicillins were used in in 41 patients [47.7%], 3GCs in 21 patients [24.4%], quinolones in 19 patients [22.1%], carbapenems in 3 patients and tigecyclin in 1 patient. Empirical antibiotic therapy combination with metronidazole was used in 28 patients [26 as combination therapy with 3GCs or quinolones]. The complete antimicrobial resistance profile was available in 83 out of 86 patients treated with antibiotics. In 53 patients, isolated pathogens were fully susceptible to empirical antibiotic therapy, whereas antimicrobial resistance to empirical therapy was observed in 30 patients. Antibiotic regimens associated with non-susceptible pathogens were penicillin-based in 14 patients, 3GC-based regimens in 9 patients, quinolone-based in 6 patients, and monotherapy with linezolid in one patient. Administration of antibiotics before microbiological sampling showed a trend towards, but was not significantly associated with, sterile culture results [p = 0.081]. Fungi were not more frequently isolated in patients receiving antibiotics before sampling [16.4% vs 10.0%, p = 1.000] Culture findings of microorganisms with antimicrobial resistance leading to change in empirically chosen antibiotic treatment were Candida spp. in 8 patients, Enterococcus spp. in 11 patients [9 E. faecium, 2 E. faecalis], gram-negative Enterobacteriacae in 15 patients [4 ESBL, 12 quinolone-resistant], Staphylococci in 5 patients, Streptococci in 2 patients and anaerobes in 4 patients. 3.4. Outcome Based on the in vitro resistance profiles, empirical antibiotic therapy was inadequate more often in patients receiving steroids or immunosuppression [37%] than in patients without immunosuppression [10%: p = 0.001] [Table 2]. Immunosuppression was discontinued in 49.3%, continued with reduced dosing in 13.4% and continued unchanged in 34.3% of the patients. Patients treated with inadequate empiric antibiotic therapy had a significantly longer hospital stay compared with patients receiving adequate empiric antibiotic therapy [median 21 days [interquartiles 15–25] vs 13 days [interquartiles 9–20], p = 0.003], although median treatment duration did not differ [12 vs 10 days; p = 0.14]. 4. Discussion Current epidemiological data on IAAs in CD are mostly based on small cases series or retrospective monocentric data,2,13,15 and data from large prospective studies are missing. In this German prospective multicenter registry of CD patients with IAAs, we report a high rate of inadequate antimicrobial empirical first-line therapy based on obtained antimicrobial resistance profiles. Inadequate therapy was more often observed in patients receiving immunosuppressive therapy and was associated with longer hospital stay, indicating clinical relevance. It is important to note that in this cohort, in which the vast majority of patients were treated with immunosuppressants, we could not find an increased overall risk of MDR in patients treated with steroids, thiopurines or anti-TNF. Only elevated white blood cell count was associated an increased probability for quinolone or penicillin/BLI resistance. Colonic or ileocolonic disease was associated with an increased probability for 3GC-resistant pathogens. Due to lack of robust data on microbiological patterns in abscesses in Crohn’s disease, antibiotics are often selected on the basis of data on microbiological patterns in other IAI. However, there can be relevant differences in microbial spectrum in IAI based on the underlying disease. In the current study, the most frequent pathogens was E. coli, followed by Streptococcus spp. In contrast, in Reuken et al., the most frequent pathogens isolated from primary peritonitis in patients with liver cirrhosis were Enterococci,17 requiring a different antibiotic therapy. Another retrospective study described Candida spp. in 51.9% of all IAI in intensive care patients,18 whereas it was only isolated in 13.2% of the patients in the current study. The lack of robust microbiological data on pathogens in CD-associated IAAs resulted in a broad variety of antibiotic regimens in our study. Overall, 20 different antibiotic combinations were used. Antibiotic resistance is an emerging problem also in IAI,19,20 and ciprofloxacin resistance in up to two-thirds of gram-negative isolates in patients with Crohn’s diseases in a retrospective study from Korea.13 Inadequate empirical therapy was associated with a longer hospital stay [21 vs 13 days], which is in line with reported outcomes for IAI from our group21 and others,22–25 and which translates into increased mortality and costs.17,24–26 The association of white blood cell count with resistance to quinolones and broad-spectrum penicillins with BLI may help to improve future antibiotic regimens. However, there are many potential confounders of this association, underlining the need for prospective evaluation. Especially, immunosuppressive medication with prednisolone is known to elevate white blood cell count and was used frequently in patients included in the current register. Surgical or interventional procedures are other potential confounders. Compared with high rates of antibiotic resistance in other recent studies from Asia and North America, empirical therapy rates of MDR pathogens were rather low in our register, with only 4 MDR Enterobacteriacae.14,27 Antibiotic resistance was predominantly associated with the following factors. (i) Patients receiving immunosuppressive therapy with steroids had significantly more quinolone-resistant E. coli [20.0%]. Quinolone-resistance is an increasing problem in CD patients with IAI. In our study, quinolone-resistant Enterobacteriacae were isolated in 12 patients. Recent studies reported quinolone-resistance in up to two-thirds of gram-negative isolates13 in CD patients, and other studies reported high rates of quinolone resistance in IAI.11,28–30 Increasing rates of resistance are challenging the use of quinolones as first-line therapy in IAI in patients at risk, such as those with nosocomial acquisition, with previous quinolone therapy, or under steroid therapy10; these categories of patients were also identified in our study as being at risk of quinolone-resistant E. coli infections. (ii) The second factor associated with high rates of antibiotic resistance is the frequent isolation of pathogens, which are per se resistant against one class of antibiotics, such as enterococci against cephalosporins or fungi against antibiotics. Recent studies found high rates of enterococcal-associated IAI11,17 that were associated with an increase in mortality in patients suffering from acute pancreatitis31 or spontaneous bacterial peritonitis.17 Our study could not identify risk factors for infection with Enterococcus spp. in CD patients, but resistance against 3GCs was associated with colonic localization of the CD and lower CRP levels. Other risk factors associated with intra-abdominal enterococcal infections are a history of antibiotic therapy,17 nosocomial acquisition and immunosuppression.17,32,33 The second pathogen accounting for a high rate of non-susceptible therapy is Candida spp., which was isolated in 13 patients in our study [12.4%]. Other studies reported Candida in up to 28.9% of IAI in intensive care units,34 with higher rates occurring when the origin of the intra-abdominal infection is in the upper-gastrointestinal tract due to normal colonization.10,35 Intra-abdominal Candida infection is associated with a poor prognosis in patients with nosocomial acquisition36 and mortality can reach up to 48% in these patients. Other risk factors associated with mortality in Candida infection are high APACHE II Score, respiratory failure or origin of the infection from the upper gastrointestinal tract.37 Delayed antifungal therapy is known to be associated with an increase in mortality.38,39 Contrasting these facts, the calculated antifungal therapy was zero percent in our registry, despite the isolation of Candida spp. in 12.4% of the 105 patients included. Therefore, antifungal therapy has to be taken into account when choosing antimicrobial therapy in CD patients with IAAs. Current therapeutic concepts for the management of IAA in CD consist of the combination of antibiotic therapy and interventional or percutaneous drainage followed by surgical therapy if necessary.3–8 The optimum time-point for delayed surgery still has to be defined. Some authors suggest 6–8 weeks,40 whereas others recommend only 2–3 weeks.41 Percutaneous drainage can avoid surgical therapy in up to 30% of patients,3,42 and a small study could not find differences in primary outcome when comparing patients undergoing surgical therapy with those receiving antibiotic therapy only,15 but patients receiving antibiotic therapy alone had a high recurrence rate of 29%. A recent meta-analysis did not find significant differences between percutaneous and surgical drainage with respect to length of hospital stay, stoma requirement or post-procedural complications.42 Contrasting that, inadequate antibiotic therapy pre-operative is associated with an increased risk of septic complications (occurring in up to 30% of these patients) and an increased number of patients requiring a stoma.43 In order to optimize therapeutic concepts dealing with antibiotic therapy alone without surgical therapy and for the pre-operative management of CD patients with IAAs, knowledge of the antibiotic-resistance pattern is crucial for therapeutic success; therefore, microbiological sampling should be performed in order to detect resistant pathogens and to optimize antibiotic therapy. To our knowledge, this is the first prospective, multicentre register evaluating microbiological patterns and resistances in patients suffering from CD in Germany, and may therefore serve as a basis for optimizing antibiotic regimens in selection of antibiotic substances. Quinolones should not be used in patients treated with steroids or when local resistance data indicates high rates of quinolone-resistant Enterococci. Funding None declared. Conflict of Interest No author reported any conflict of interests relevant to the reported article. Author Contributions All authors participated in patient inclusion and data collection. PAR and TB performed statistical analyses and wrote the paper, AS designed the study. All authors approved the final version of the manuscript. Supplementary Data Supplementary data for this article can be found at Journal of Crohns and Colitis Online. Abbreviations. 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Google Scholar CrossRef Search ADS PubMed Copyright © 2018 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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Journal of Crohn's and ColitisOxford University Press

Published: Feb 5, 2018

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