Characteristics of Carbapenemase-Producing Enterobacteriaceae in Wastewater Revealed by Genomic Analysis.

Wastewater is considered a major source of antibiotic-resistant bacteria released into the environment. Here, we characterized carbapenemase-producing (CPE) in wastewater by whole-genome analysis. Wastewater samples ( = 40) were collected from municipal wastewater treatment plants and hospital wastewater in Japan and Taiwan. Samples were screened for CPE using selective media, and the obtained isolates were sequenced using an Illumina MiSeq. The isolates ( = 45) included the following microorganisms: ( = 12), ( = 10), complex ( = 10), ( = 8), ( = 2), ( = 1), ( = 1), and ( = 1). Among the 45 isolates, 38 harbored at least one carbapenemase-encoding gene. Of these, the (, , and ) genes were found in 29 isolates. The genes were situated in novel class 1 integrons, but the integron structures were different between the Japanese (In1439 with and In1440 with ) and Taiwanese (In1441 with and In1442 with ) isolates. Other carbapenemase-encoding genes (, , , , and ) were found in one to three isolates. Notably, class 1 integrons previously reported among clinical isolates obtained in the same regions as the present study, namely, In477 with and In73 with , were found among the Japanese and Taiwanese isolates, respectively. The results indicate that CPE with various carbapenemase-encoding genes in different genetic contexts were present in biologically treated wastewater, highlighting the need to monitor for antibiotic resistance in wastewater.