Propagation of New Delhi Metallo-β-lactamase Genes (blaNDM-1) from a Wastewater Treatment Plant to Its Receiving River

The emergence and spread of NDM-1 (New Delhi metallo-β-lactamase-1) are of great concern to public health. Our previous study reported the occurrence and persistence of NDM-1 genes in wastewater treatment plants (WWTPs). In this study, the occurrence and fate of NDM-1 genes and host bacteria were investigated in a WWTP discharge-receiving river. A considerable level of NDM-1 genes occurred in the receiving river, whereas no NDM-1 genes were detected upstream of the WWTP. This finding together with the DNA sequencing of NDM-1 genes demonstrated that the river NDM-1 is derived from the WWTP. Opportunistic pathogens, like Shigella sonnei, Enterococcus faecium, and Wautersiella falsenii, were isolated from both the receiving water and the WWTP. This study underscores the need to mitigate the release of NDM-1 from WWTPs and indicates that more attention should to be paid to the propagation of these genes to the receiving environment to alleviate their worldwide dissemination.