Tracking dissemination of antimicrobial resistance from a hospital to surface water via a municipal wastewater treatment plant using a carbapenemase gene. Klebsiella oxytoca

Antibiotic resistant bacteria originating from hospitals are ultimately discharged to municipal wastewater treatment plants (WWTP), which may serve as important reservoirs for the spread of antibiotic resistant genes. This study traced and quantified the presence of a rare but clinically relevant antimicrobial resistance gene; Klebsiella pneumoniae carbapenamase (KPC)-and the viable organisms which carried the gene (KPCO) in hospital, non-hospital wastewater discharges, various compartments within the WWTP, and receiving water and sediment samples. The KPC gene was present in high concentration along with viable and multispecies KPCO in the hospital wastewater and in the forepart stages of the WWTP, but not detected in the final effluent. KPCO were not detected in multiple non-hospital sources of wastewater discharges tested. The treatment train used in the sampled WWTP was found to help remove and reduce KPCO load. Using whole-genome sequencing, a KPC-producing Klebsiella oxytoca strain identical to strains seen in the patients and hospital was isolated from the downstream receiving water on one sampling event. This study systematically demonstrates dissemination of KPCO from hospital point sources to environment via municipal WWTP. KPCE were also found to persist in the biosolids, but were not detected in the processed composting products. Understanding hospitals as the origin and source of spread of some of the most clinically urgent antimicrobial resistant organisms may help direct interventions to improve efficiency and reliability of elimination of antimicrobial resistant organisms via enhancement of wastewater treatment and reduce their loading into the environment.