Researchers from the Centre for Cellular and Molecular Biology and partner institutions have identified widespread antimicrobial resistance (AMR) genes in bacteria present in urban wastewater across major Indian cities, highlighting the scale of a growing public health concern.
The findings, published in Nature Communications, are based on one of the most comprehensive studies of its kind in India, mapping AMR genes across multiple metropolitan regions.
The study analysed 447 wastewater samples collected between March 2022 and March 2024 from 19 sites across four major cities, Delhi, Mumbai, Kolkata and Chennai.
Using advanced “shotgun metagenomics” techniques, researchers examined bacterial genetic material to understand how resistance to antibiotics develops and spreads. Antimicrobial resistance occurs when bacteria evolve mechanisms to survive drugs designed to kill them, making infections harder to treat and increasing the risk of disease spread, severe illness and death.
The study found that while microbial communities varied depending on local environmental conditions, resistance genes remained largely consistent across
all four cities.
Also read: Telangana joins Kerala in crackdown on misuse of antibiotics
“The study finds that the microbial communities shifted based on local environmental factors. For example, Klebsiella pneumoniae is more abundant in Chennai and Mumbai, and Pseudomonas aeruginosa in Kolkata. But the genes conferring resistance to various antibiotics remained consistent across all four metro cities,” the researchers said.
The findings also showed that bacteria share resistance genes more easily for certain classes of antibiotics, particularly tetracyclines and beta-lactams, compared to macrolides.
Antimicrobial resistance is already recognised as a major global health threat, contributing to millions of deaths each year and posing significant challenges to modern medicine by reducing the effectiveness of existing treatments.
Beyond identifying the scale of the problem, the researchers have proposed expanding wastewater-based pathogen surveillance in India as a practical tool for early detection and monitoring of AMR trends.
They said such surveillance could help public health systems respond more effectively, despite infrastructure constraints in different regions, by providing real-time insights into the spread of drug-resistant bacteria.
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