Isolation and characterization of NDM-positive Escherichia coli from municipal wastewater in Jeddah, Saudi Arabia

The emergence of resistance to last resort antibiotics is a public health concern of global scale. Besides direct person-to-person propagation, environmental pathways might contribute to the dissemination of antibiotic-resistant bacteria and antibiotic resistance genes (ARGs). Here, we describe the incidence of blaNDM-1, a gene conferring resistance to carbapenems, in the wastewater of Jeddah city over a one-year period. blaNDM-1 was detected at concentrations ranging from 104 to 105 copies per m3 of untreated wastewater during the entire monitoring period. These results indicate the ubiquity and high incidence of blaNDM-1 in the local wastewater. To track the bacteria carrying blaNDM-1, we isolated Escherichia coli PI7, a strain of the sequence type ST101, from wastewater around the Hajj event in October 2013. Genome sequencing of this strain revealed an extensive repertoire of ARGs as well as virulence and invasive traits. These traits were further confirmed by antibiotic resistance profiling and in-vitro cell internalization in HeLa cell cultures. Given that this strain remains viable even after a certain duration in the sewerage, and that Jeddah lacks a robust sanitary infrastructure to fully capture all generated sewage, the presence of this bacterium in the untreated wastewater would represent a potential hazard to the local public health. To the best of our knowledge, this is the first report of a blaNDM-1-positive E. coli isolated from a non-nosocomial environment in Saudi Arabia, and may set a preceding concern for the need to establish an improved surveillance for carbapenem-resistant E. coli in the country and nearby regions.