Discharge of KPC-2 genes from the WWTPs contributed to their enriched abundance in the receiving river

At present, very little is known about the persistence and spread pathway of KPC-2 genes in the environment Our previous study reported the prevalence and persistence of KPC-2 genes in wastewater treatment plants (WWTPs). In the present work, we investigated the occurrence and fate of KPC-2 genes in a WWTP discharge-receiving river and studied the effect of WWTP discharges on the prevalence of KPC-2 genes and host bacteria in the receiving river. It is observed that a considerable level` of KPC-2 genes occurred in the receiving river, and a significant increase of bla(Kpc-2) abundance in the downstream following WWTP discharge was observed compared to the upstream. Furthermore, opportunistic pathogens with 100% identical bla(kpc-2) sequence, like Escherichia coli and Kluyvera georgiana, were isolated from both WWTP and its receiving water, whereas no bla(kpc-2) carrying bacteria was detected in the upstream. These findings indicated that the treated wastewater discharges have a considerable influence on bla(kpc-2) levels in the receiving river. Interestingly, there is no correlation between concentrations of antibiotics and bla(kpc-2) concentrations, demonstrating that the increase of KPC-2 genes in the receiving river is mainly due to WWTP release. This finding is important because it illustrates a significant pathway for KPC-2 gene proliferation to the environment