Antibiotic resistance in the Ganga River: Investigation of antibiotic resistant bacteria and antibiotic resistance genes, and public health risk assessment

The Ganga River, sacred to India and supporting 440 million people, faces a severe threat from antibiotic resistance. Here, we have investigated the abundance of antibiotic resistant bacteria (ARB), antibiotic resistant genes (ARGs), and mobile genetic elements (MGEs) in water and sediment samples at 16 different sites across the Ganga River biannually. Furthermore, we investigated the presence of potentially pathogenic ARB at genus level in the Ganga River and conducted a risk assessment for human exposure to ESKAPE pathogens during swimming activities. Among the sites studied, a notably higher abundance of ARB, ARGs, and MGEs was observed downstream of the pristine sites (G1 and G2) due to anthropogenic inputs. A significant positive correlation (p < 0.05) was observed between ARB, ARGs, MGEs, and coliforms, suggesting a close association between faecal contamination and MGEs in the spread of antibiotic resistance in the river. Of the identified, 10,340 isolates, Pseudomonas, Bacillus, Acinetobacter, Pseudoxanthomonas, and Aeromonas were the top five most abundant genera. The dominant potentially pathogenic ARB were Pseudomonas, Acinetobacter, Aeromonas, Stenotrophomonas, and Brevundimonas. The results of the Quantitative Microbial Risk Assessment (QMRA) and the analysis of disability-adjusted life years (DALYs) indicated that Enterobacter cloacae posed the highest risk, followed by Acinetobacter baumannii and Klebsiella pneumoniae. Overall, this study provides quantitative data on antibiotic resistance and human health risks in the Ganga River. The data from this study can serve as a foundational basis for guiding crucial actions and policy recommendations for safeguarding the Ganga River and the well-being of its users.