HYDERABAD: In a significant step towards understanding the silent spread of drug-resistant bacteria, scientists from CSIR-Centre for Cellular and Molecular Biology (CCMB) and partner institutions have mapped antimicrobial resistance (AMR) genes in urban wastewater across India’s four largest cities.
Published in Nature Communications, the study offers the first comprehensive national picture of resistance patterns. “Researchers analysed 447 samples collected between March 2022 and March 2024 from 19 locations across Delhi, Mumbai, Kolkata and Chennai, using an advanced ‘shotgun metagenomics’ approach to decode bacterial genetic material,” a scientist involved in the study told TNIE.
Antimicrobial resistance occurs when bacteria evolve to withstand antibiotics, making treatments ineffective. While a global concern, India has lacked detailed, location-specific data. The study addresses this gap, showing that although dominant bacteria vary across cities, resistance mechanisms remain largely similar.
“For instance, Klebsiella pneumoniae (that can cause pneumonia, UTIs and infections) was found to be more prevalent in Chennai and Mumbai, while Pseudomonas aeruginosa (known to cause bloodstream infections, surgical site infections and UTI/catheter infections) dominated samples from Kolkata. Despite this variation, the genes that enable resistance — such as those that strengthen bacterial cell walls, break down antibiotics or expel them from cells — were consistently present across all cities,” the scientist said.
These genes help bacteria block, neutralise or expel antibiotics and can spread across species, accelerating resistance. The study also found that resistance linked to commonly used antibiotics spreads more easily than others.
Researchers stressed the need to scale up wastewater-based surveillance as a cost-effective tool to monitor infections and detect emerging threats early. They also developed a method to store samples for up to seven days without loss of quality, enabling wider adoption even in resource-limited settings.
Experts say such systems could allow real-time tracking of drug-resistant pathogens and strengthen outbreak preparedness.