Novel insights into genetic characteristics of -encoding plasmids from hospital sewage.

INTRODUCTION

The prevalence of Guiana extended-spectrum (GES)-type carbapenemase producers is increasing worldwide, and hospital water environments are considered as potential reservoirs. However, the genetic features underlying this resistance are not yet fully understood. This study aimed to characterize -encoding plasmids from a single-hospital sewage sample in Japan.

METHODS

Carbapenemase producers were screened using carbapenemase-selective agar and polymerase chain reaction. Whole-genome sequencing analyzes were performed on the carbapenemase-producing isolates.

RESULTS

Eleven gram-negative bacteria (four spp., three spp., three spp., and one spp.) with ( = 6), ( = 4), and ( = 1) were isolated from the sewage sample. Five and a were localized in IncP-6 plasmids, whereas three plasmids were localized in IncC plasmids with IncF-like regions. The remaining and were, respectively, localized on IncFIB-containing plasmids with IncF-like regions and a plasmid with an IncW-like replication protein. The IncP-6 and IncW-like plasmids had a close genetic relationship with plasmids from Japan, whereas the IncC/IncF-like and IncFIB/IncF-like plasmids were closely related to those from the United States and Europe. All genes were located on the class 1 integron cassette of the Tn transposon-related region, and the IncC/IncF-like plasmid carried two copies of the integron cassette. Eight of the eleven -encoding plasmids contained toxin-antitoxin system genes.

DISCUSSION

The findings on the plasmids and the novel genetic content from a single wastewater sample extend our understanding regarding the diversity of resistance and the associated spread of , suggesting their high adaptability to hospital effluents. These findings highlight the need for the continuous monitoring of environmental GES-type carbapenemase producers to control their dissemination.