抄録
Carbapenemase-producing Enterobacteriaceae (CPE) have been reported worldwide, but the types of carbapenemase vary between countries. Metallo-beta-lactamase (MBL) IMP (blaIMP) is the most common type of carbapenemase in Japan. CPE outbreaks occurred in our hospital's neonatal intensive care unit (NICU) between October 2014 and October 2015. The aim of this study was to evaluate the results of active surveillance and to establish more effective CPE detection methods. We also investigated the molecular epidemiological characteristics of CPE in Japan. During the outbreak period, active surveillance was performed on a weekly basis by analyzing fecal cultures from all patients admitted to the NICU. Between January 2014 and December 2015, which included the outbreak period described above, Enterobacteriaceae strains isolated by fecal culture or from clinical specimens were analyzed by antimicrobial susceptibility testing and double-disc synergy testing (DDST) using ceftazidime or imipenem with sodium mercaptoacetic acid, polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE), and conjugal transfer experiments. During the outbreak period we analyzed 1073 isolates detected by fecal culture from 285 patients. Of these, we detected 64 blaIMP-producing Enterobacteriaceae from 52 patients, all of whom were asymptomatic carriers (52/285, 18.2%). Klebsiella pneumoniae (33/64 strains, 51.6%) and Enterobacter cloacae (20/64 strains, 31.3%) were the predominant species. Of the 64 blaIMP-producing Enterobacteriaceae, 7 strains were susceptible to imipenem and meropenem. Active surveillance by fecal culturing and DDST of carbapenem-resistant and third-generation cephalosporin-resistant pathogens may be an effective strategy for identifying CPE carriers. Therefore, this strategy may contribute to infection control and prevent further spread of disease in healthcare settings.
