Insights into the circulation of carbapenem resistance in several Enterobacteriaceae species from wastewater and a hospital source mediated by a novel blaKPC-2-encoding IncP-6 plasmid

Untreated wastewater, particularly from hospitals and other healthcare facilities, is considered to be a reservoir for multidrug-resistant bacteria. However, its role in the spread of antibiotic resistances in the human population remains poorly investigated. We used whole genome sequencing (WGS) to analyze 25 KPC-2-producing Enterobacteriaceae isolates from sewage water collected during a 3-year period and three clinical Citrobacter freundii isolates from a tertiary hospital in the same catchment area. We detected a common IncP-6 plasmid carrying the gene blaKPC-2 in 21 isolates from both sources. The plasmid was present in diverse environmental bacterial species of opportunistic pathogens such as C. freundii, Enterobacter cloacae, Klebsiella oxytoca, and Raoultella ornithinolytica.The 40,186 bp IncP-6 plasmid encoded 52 coding sequences (CDS) and the region harboring the carbapenem resistance gene (14 kb) contained a Tn3 transposon disrupted by an ISApu-flanked element. We document here the presence of a novel promiscuous blaKPC-2 plasmid circulating in environmental bacteria in wastewater and human populations.