Using Arabian Sea Coastal Water as a Model to Study Plasmid-mediated AMR Dissemination driven by Anthropogenic Impacts

Background Antimicrobial resistance (AMR) is a growing global public health threat. The water bodies act as both reservoirs and medium for dissemination of AMR. Coastal water driven by anthropogenic effects accumulate antibiotics, heavy metals, microplastics, and disinfectants which act as stressors, increasing the overall AMR. Therefore, it is necessary to understand the AMR entities and its transmission in coastal water bodies. Methods and Results Mumbai, mirroring most cosmopolitan cities of the world, was used as a model to understand how rapid urbanization disseminate AMR in coastal waters of the Arabian Sea and can pose substantial risk to human health. Bacteria isolated from coastal waters were screened and found to be multi-drug resistant. Several isolates carried multiple plasmids of high molecular weight (>10 kb). Plasmid sequencing and analysis using various bioinformatic tools identified plasmid replicons like IncFIA, IncFII, rep7a and repUS43. Analysis showed a high burden of antibiotic resistance genes (ARGs) conferring resistance to antibiotic classes such as monobactams (blaTEM-116), carbapenems (blaNDM-5), vancomycin (vanA), disinfectants and antiseptics (qacG). Additionally, clinically relevant mecA and mecR1 associated with methicillin-resistant Staphylococcus sp., rpsL associated with streptomycin resistant Mycobacterium tuberculosis and the colistin-resistance genes mcr-10.1 and mcr-10.4 were also detected. We also report for the first-time presence of a plasmid-borne mupB gene in coastal waters, that confers high resistance to mupirocin. Conclusions Despite the moderate sample size, the presence of diverse plasmid replicons and clinically important ARGs suggests urban coastal environment as a potent reservoir of AMR, with potential for global transmission through active waterway trade and transport.