Abstract
BACKGROUND: In 2010, a multispecies outbreak of IMP type carbapenemase-producing Enterobacteriaceae (IMP-CPE) occurred at a large acute care hospital in Japan. The outbreak continued for years involving more than 100 patients mainly in surgical wards. METHODS: Because of the long period of the outbreak, investigation were focused on hospitalized patients whose clinical samples were positive for IMP-CPE between July 2013 and March 2014. A case–control study was conducted for cases who underwent abdominal surgery with controls from whom meropenem-susceptible Enterobacteriaceae were isolated. Pulsed-field gel electrophoresis (PFGE) was used for molecular typing. To evaluate genetic relationship among IMP-CPE isolates of different species, plasmid analysis using S1 nuclease to separate plasmid and chromosomal DNA followed by plasmid DNA extraction and whole-genome sequencing (WGS) was conducted. RESULTS: During the study period, 22 cases were identified and 22 IMP-CPE isolates which consisted of eight Escherichia coli, five Klebsiella oxytoca, five Enterobacter cloacae, three Klebsiella pneumoniae and one Enterobacter aerogenes were obtained. All five isolates of K. oxytoca had similar PFGE profiles which suggested clonal transmission. However, PFGE profiles of E. coli, E. cloacae and K. pneumoniae isolates were diverse. Plasmid analysis revealed that all 22 isolates shared ca. 50 kb IncN plasmid with bla(IMP-6) which implies interspecies transmission of it The case–control study which adjusted by days of hospitalization with 11 cases and 24 controls revealed that pancreato-duodenectomy (adjusted odds ratio (aOR) = 6.4, 95% confidence interval (CI) 1.3–32.4) and enteric fistula (aOR = 8.0, 95% CI 1.5–41.9) were associated with IMP-CPE acquisition. Use of endoscopy within the past six months was not associated with IMP-CPE (aOR = 0.8 95% CI 0.2–4.2). With a bundled infection control with Osaka City Public Health Office, the outbreak was contained in July 2016. CONCLUSION: Dissemination of carbapenemase gene by transmissible plasmid can play a critical role to complicate epidemiology of CPE outbreak and made it difficult to control. Plasmid analysis using WGS technology is a promising tool to untangle it. DISCLOSURES: All authors: No reported disclosures.