A high prevalence of in () and related species in hospital wastewater in South West England.

species occupy a wide range of environmental and animal niches, and occasionally cause opportunistic infections that are resistant to multiple antibiotics. In particular, () has gained notoriety as a major nosocomial pathogen, due principally to the rise in non-susceptibility to carbapenems and other beta-lactam antibiotics. Whilst it has been proposed that the urban water cycle facilitates transmission of pathogens between clinical settings and the environment, the level of risk posed by resistant strains in hospital wastewater remains unclear. We used whole genome sequencing (WGS) to compare species in contemporaneous samples of wastewater from an English hospital and influent to the associated wastewater treatment plant (WWTP). As we aimed to characterize representative samples of communities, we did not actively select for antibiotic resistance (other than for ampicillin), nor for specific species. Two species, and . () (), were of equal dominance in the hospital wastewater, and four other species were present in low abundance in this sample. In contrast, despite being the species most closely associated with healthcare settings, was the dominant species within the WWTP influent. In total, 29 % of all isolates harboured the gene on a pOXA-48-like plasmid, and these isolates were almost exclusively recovered from the hospital wastewater. This gene was far more common in (68 % of isolates) than in (3.4 % of isolates). In general plasmid-borne, but not chromosomal, resistance genes were significantly enriched in the hospital wastewater sample. These data implicate hospital wastewater as an important reservoir for antibiotic-resistant , and point to an unsuspected role of species within the group in the maintenance and dissemination of plasmid-borne . This article contains data hosted by Microreact.