Epidemiology and virulence-associated genes of Clostridioides difficile isolates and factors associated with toxin EIA results at a university hospital in Japan.

INTRODUCTION: Clostridioides difficile is one of the most important nosocomial pathogens; however, reports regarding its clinical and molecular characteristics from Japan are scarce. AIMS: We studied the multilocus sequence typing (MLST)-based epidemiology and virulence-associated genes of isolates and the clinical backgrounds of patients from whom the isolates had been recovered. METHODS: A total of 105 stool samples tested in a C. difficile toxin enzyme immune assay (EIA) were analysed at the University of Tokyo Hospital from March 2013 to July 2014. PCR for MLST and the virulence-associated genes tcdA, tcdB, cdtA, cdtB and tcdC was performed on C. difficile isolates meeting our inclusion criteria following retrospective review of medical records. EIA-positive and EIA-negative groups with toxigenic strains underwent clinical and molecular background comparison. RESULTS: The toxigenic strains ST17, ST81, ST2, ST54, ST8, ST3, ST37 and ST53 and the non-toxigenic strains ST109, ST15 and ST100 were frequently recovered. The prevalence rate of tcdA-negative ST81 and ST37, endemic in China and Korea, was higher (11.4%) than that reported in North America and Europe, and hypervirulent ST1(RT027) and ST11(RT078) strains that occur in North America and Europe were not recovered. The linkage between the EIA results and cdt A/B positivity, tcdC deletion, or tcdA variation was absent among toxigenic strains. Compared with the 38 EIA-negative cases, the 36 EIA-positive cases showed that the patients in EIA-positive cases were older and more frequently had chronic kidney disease, as well as a history of beta-lactam use and proton pump inhibitor therapy. CONCLUSION: In Japan, the prevalence rates for tcdA-negative strains are high, whereas the cdtA/B-positive strains are rare. EIA positivity is linked to older age, chronic kidney disease and the use of beta-lactams and proton pump inhibitors.

Prevalence and characteristics of fecal antimicrobial-resistant Escherichia coli in a cohort of Japanese men undergoing prostate biopsy.

OBJECTIVES: To examine resistant Escherichia coli in rectal swab culture of Japanese men undergoing prostate biopsy, and to determine its prevalence, genotypic characteristics and carriage risk factors. METHODS: Rectal swabs of consecutive men undergoing transrectal ultrasound-guided prostate biopsy from April 2013 to March 2015 were cultured to isolate fluoroquinolone-resistant and extended-spectrum ß-lactamase-producing E. coli. The prevalence and antimicrobial susceptibility of these resistant E. coli strains and extended-spectrum ß-lactamase genotyping were examined. The risk factors of antimicrobial resistance carriage were also examined. RESULTS: The cohort was 376 men with a mean age of 67.8 years. Fluoroquinolone-resistant E. coli and extended-spectrum ß-lactamase-producing E. coli were detected in 37 men (9.8%) and 22 men (5.9%), respectively, with fluoroquinolone-resistant and/or extended-spectrum ß-lactamase-producing E. coli in 48 men (13.0%). All 49 antimicrobial-resistant strains were susceptible to tazobactam/piperacillin, amikacin, fosfomycin, meropenem and faropenem. CTX-M-9 and CTX-M-1 group were detected in 14 (63.6%) and eight (36.4%) men, respectively. CTX-M-9 showed relatively higher susceptibility to LVFX and minocycline compared with CTX-M-1. Diabetes mellitus was a significant factor for carriage of resistance by multivariate analysis (odds ratio 2.12, P = 0.039). CONCLUSIONS: The present study showed the fecal carriage of fluoroquinolone-resistant E. coli and extended-spectrum ß-lactamase-producing E. coli at 9.8% and 5.9%, respectively, with CTX-M-9 group of extended-spectrum ß-lactamase-producing E. coli comprising 63.6%, in Japanese men receiving prostate biopsy. The carriage of fluoroquinolone-resistant and/or extended-spectrum ß-lactamase-producing E. coli was significantly related to diabetes.

Diagnosing Clostridium difficile-associated diarrhea using enzyme immunoassay: the clinical significance of toxin negativity in glutamate dehydrogenase-positive patients.

PURPOSE: The enzyme immunoassay (EIA) has lower sensitivity for Clostridium difficile toxins A and B than the polymerase chain reaction in the diagnosis of C. difficile-associated diarrhea (CDAD). Furthermore, toxin positivity with EIA performed on C. difficile isolates from stool cultures may be observed even in patients with EIA glutamate dehydrogenase (GDH)-positive and toxin-negative stool specimens. It is unclear whether such patients should be treated as having CDAD. METHODS: The present study retrospectively compared patient characteristics, treatment, and diarrhea duration among three groups of patients who underwent stool EIA testing for CDAD diagnosis: a toxin-positive stool group (positive stool group; n=39); a toxin-negative stool/toxin-positive isolate group (discrepant negative/positive group, n=14); and a dual toxin-negative stool and isolate group (dual negative group, n=15). All cases included were confirmed to be GDH positive on EIA test. RESULTS: Patients' backgrounds and comorbidities were not significantly different among three groups. No difference was observed among the three groups with regard to antimicrobial drug use before diarrhea onset. Treatment was received by 82.1% of the positive stool group compared to 7.1% of the discrepant positive/negative group and 0% of the dual negative group, while mean diarrhea duration was 10.6 days compared to 7.9 days (P=0.6006) and 3.4 days (P=0.0312), respectively. CONCLUSION: Even without treatment, patients with toxin-negative stool specimens had shorter diarrhea duration than those with toxin-positive stool specimens even with toxin-positive isolates. These findings may suggest a limited need for CDAD treatment for GDH-positive patients and toxin-negative stool specimens.

Clinical characteristics and antimicrobial susceptibility of Bacillus cereus blood stream infections.

BACKGROUND: Bacillus cereus is one of the pathogens causing nosocomial bloodstream infections (BSIs). However, few reports have documented the antimicrobial susceptibility and clinical characteristics of Bacillus cereus BSI and the importance of empirical therapy. The aim of this study was to investigate the clinical characteristics and antimicrobial susceptibility of B. cereus isolates from patients with BSI and to analyze the impact of appropriate empirical therapy on the outcome of patients with B. cereus BSI. METHODS: All adult cases of bacteremia between April 2003 and March 2012 in a teaching hospital in Tokyo, Japan were reviewed retrospectively. Clinical data were collected from the patients' medical records and charts. Antimicrobial susceptibility testing was performed by broth microdilution method. The patients with B. cereus BSI were divided into an appropriate empirical therapy group and an inappropriate empirical therapy group. The primary outcome was all-cause mortality at 4 weeks after the start of BSI. The secondary outcome was early defervescence within 2 days after starting empirical therapy. RESULTS: There were 29 B. cereus bloodstream infection cases. No vancomycin, gentamicin, and imipenem-resistant isolates were found. However, 65.5 % were resistant to clindamycin and 10.3 % were resistant to levofloxacin. The main etiology was venous catheter-related (69 %). All-cause mortality at 4 weeks was not significantly different between the appropriate empirical therapy group (9 cases) and the inappropriate group (20 cases) in this study. However, early defervescence within 2 days after starting empirical therapy was significantly different (p = 0.032). CONCLUSIONS: The BSI of B. cereus is mostly caused by venous catheter-related infections. Appropriate empirical therapy is important to achieve early clinical resolution in B. cereus BSI. Vancomycin is one of the appropriate selections of empirical therapy for B. cereus BSI.