Molecular epidemiology of carbapenemase-producing Enterobacteriaceae in a primary care hospital in Japan, 2010-2013

摘要

Recently, carbapenemase-producing Enterobacteriaceae (CPE) have been spreading worldwide and have become a threat in healthcare systems. We investigated the isolation frequency and molecular epidemiological characteristics of CPE isolated from clinical samples collected at a primary care hospital over the four years of 2010-2013 in Japan. CPE were detected in 17 (0.34%) of 4875 isolates by the broth microdilution method, sodium mercaptoacetate inhibition test, and modified Hodge test using meropenem disks. The frequency of CPE isolates was 0.09% in 2010, 0.17% in 2011, 0.16% in 2012 and 0.82% in 2013. Isolates positive for carbapenemase included Klebsiella pneumoniae (0.92%), Escherichia coli (0.12%), Enterobacter cloacae (0.80%), Klebsiella oxytoca (0.55%), Enterobacter aerogenes (0.81%) and Proteus mirabilis (0.08%). Antimicrobial susceptibility testing showed low MICs for piperacillin-tazobactam, amikacin, ciprofloxacin and levofloxacin, and only one multidrug-resistant strain. The carbapenemase genotype of all strains was IMP-6, and 94% of the strains were simultaneous CTX-M-2 producers. Two K. pneumoniae and 3 E. coli isolates showed the same pulsed-field gel electrophoresis group. Multilocus sequence typing detected no international high-risk clone types. Plasmid replicon typing detected IncN from all CPE strains, and IncF and IncFIB were simultaneously detected in 24% and 18%, respectively. All patients with detected CPE were inpatients, and many were elderly long-term hospitalized patients or had a history of prior vancomycin or levofloxacin antibiotic administration. The rapid spread of CPE is a concern in Japan. Preventive measures must be implemented against the spread of CPE after considering the epidemiological trend of CPE detection, antibiograms, and risk factors. (C) 2017 Published by Elsevier Ltd on behalf of Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases.