MOLECULAR CHARACTERIZATION OF EXTENDED-SPECTRUM BETA-LACTAMASE PRODUCING GENES OF ENTEROBACTERIACEAE ISOLATED FROM MUNCIPAL AND HOSPITAL WASTEWATERS

Abstract

 Extended spectrum β-lactamase (ESBL)-producing Enterobacteria (ESBL-Ent), which are resistant to a wide range of antibiotics in beta-lactam group, have been recognized worldwide as a threat causing nosocomial infections. To characterize the ESBL-Ent carried by healthy people, we isolated the bacteria from municipal wastewater (MW) and detected genes (bla) cording β-lactamase production. The same analysis was applied to hospital wastewater (HW) for comparison. Wastewater samples were taken from a municipal wastewater treatment plant and a general hospital twice a month throughout a year from February 2019 in Sendai, Miyagi prefecture, Japan. By incubating on CHROMOagar ESBL, 594 and 102 isolates of ESBL-Ent were obtained from MW and HW, respectively. The species identification of each isolate with detection of specific gene (for Escherichia coli) and sequencing of 16S rRNA (for Enterobacteria) found ten bacterial genera including mainly E. coli, Aeromonas, and Klebsiella. Among 20 types tested, 16 types of bla were detected from these isolates. The classification of detected bla demonstrated that Class A was predominant and, in this class, bla_{CTX-M group-9} had the highest prevalence in both wastewaters (MW: 51.9%, HW: 35.6%). ESBL-Ent possessing Class A and Class B genes simultaneously, which can degrade peniciline and carbapenem groups of antibiotics, were detected in both MW (1 isolate) and HW (2 isolates). Two important resistance genes bla_KPC and bla_OXA-1, called overseas carbapenemase in Japan, were also detected from MW and HW isolates. These results indicated that ESBL-Ent, a fraction of which potentially cause infectious diseases difficult to be treated, have been already spread among healthy people living outside hospitals.