Genetic features of BEL-1-producing and KPC-2-producing E. coli from hospital wastewater: human source or sewages adaptation

TL;DR

The study investigates E. coli isolates from hospital wastewater that produce BEL-1 and KPC-2 enzymes, suggesting they adapted to sewage rather than coming directly from patients.

Contribution

The paper presents evidence that BEL-1-producing E. coli may have evolved in hospital sewage ecosystems rather than originating from human sources.

Findings

BEL-1 and KPC-2 co-producing E. coli isolates were found in hospital wastewater over 10 months.

The isolates carried similar plasmids with shared genetic regions and a phage-like structure, suggesting in situ adaptation.

No colonized patients were found, supporting the idea that these isolates originated in the sewage environment.

Abstract

Hospital sewage is an ecosystem that facilitates the transfer of antibiotic and heavy metal resistance genes and the interaction of human and environmental bacteria. In this environment, we have detected the presence of 7 KPC-2 and BEL-1 co-producing E. coli isolates of two different clones over a 10-month period in the same hospital. All isolates carried blaKPC-2 and the operon mer on the same IncP plasmid of similar size and an IncN plasmid of different size each clone carrying blaBEL-1. Both IncN-blaBEL-1 plasmids shared a 77 kb region containing blaBEL-1 alongside with fosE, bla
OXA-10 and aac(6’)-1b genes in a class 3 integron within a Tn3 transposon. The major IncN plasmid contained in addition a region homolog to P1-like bacteriophage RCS47, including the lytic RepL and lysogenic proteins, but other phage regions were incomplete. The characters such as the temporal persistence in sewage, the absence of colonized patients in the hospital or in the region, the presence of a p1 phage-plasmid fusion and the infrequent class 3 integron as genetic platform would indicate that BEL-1-producing isolates could have been generated in situ by adaptation to human sewage. Part of the microbiota in these discharges could be explained by the interactions of sewage ecosystems and not derive directly from the hospital.

The online version contains supplementary material available at 10.1007/s11356-024-33875-w.

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