Deciphering the antimicrobial resistomes and microbiome landscape of open drain wastewater using metagenomics in a...

Antimicrobial resistance (AMR) is a growing environmental and public health concern, with wastewater systems are acting as a critical reservoirs for resistant microorganisms and genes. Open drains in densely populated and industrialized regions can accelerate AMR dissemination into the environment. Despite Maharashtra's high urban density and industrial activity, comprehensive metagenomic surveillance of its wastewater resistome is lacking. This study applied high-throughput nanopore sequencing to 138 wastewater samples collected from 23 open-drain sites across three regions of Maharashtra (Western, Mumbai, and Central). Bioinformatic pipelines were used to characterize microbial communities, resistance genes, mobile genetic elements (MGEs), and resistome risk scores. Microbial composition varied significantly across regions, with Mumbai and Central regions explaining up to 13 % of variance at the family level. Thirty indicator taxa were identified through LEfSe analysis. Resistome profiling revealed 28 drug classes and 808 ARGs, dominated by multidrug (40.49 %), macrolide-lincosamide-streptogramin (15.84 %), beta-lactam (7.95 %), and tetracycline (6.52 %). WHO-priority pathogens such as Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa harbored high-abundance ARGs including sul1, mdr(ABC), and acrB. Resistome risk scores were highest in Mumbai, indicating elevated ecological and human health risks. These findings underscore wastewater as a hotspot for AMR persistence and spread. Integrating wastewater-based surveillance within a One Health framework enables systematic tracking of resistance trends, comprehensive assessment of environmental risks, and evidence-driven regional interventions. This integrated approach supports the development of targeted mitigation strategies to curb the spread of antibiotic-resistant contaminants across ecosystems.