High Prevalence of Drug Resistance and Class 1 Integrons in Isolated From River Yamuna, India: A Serious Public Health Risk.

Globally, urban water bodies have emerged as an environmental reservoir of antimicrobial resistance (AMR) genes because resistant bacteria residing here might easily disseminate these traits to other waterborne pathogens. In the present study, we have investigated the AMR phenotypes, prevalent plasmid-mediated AMR genes, and integrons in commensal strains of , the predominant fecal indicator bacteria isolated from a major urban river of northern India Yamuna. The genetic environment of was also investigated. Our results indicated that 57.5% of the strains were resistant to at least two antibiotic classes and 20% strains were multidrug resistant, i.e., resistant to three or more antibiotic classes. The multiple antibiotic resistance index of about one-third of the strains was quite high (>0.2), reflecting high contamination of river Yamuna with antibiotics. With regard to plasmid-mediated AMR genes, was present in 95% of the strains, followed by qS1 and A (17% each), (15%), AB (12%), and A (7%). Contrary to the earlier reports where was mostly associated with pathogenic phylogroup B2, our study revealed that the CTX-M-15 type extended-spectrum β-lactamases (ESBLs) were present in the commensal phylogroups A and B1, also. The genetic organization of was similar to that reported for , isolated from other parts of the world; and IS was present upstream of . The integrons of classes 2 and 3 were absent, but class 1 integron gene was present in 75% of the isolates, denoting its high prevalence in of river Yamuna. These evidences indicate that due to high prevalence of plasmid-mediated AMR genes and , commensal can become vehicles for widespread dissemination of AMR in the environment. Thus, regular surveillance and management of urban rivers is necessary to curtail the spread of AMR and associated health risks.