India's Urban Wastewater Reveals Alarming Map of Antibiotic Resistance

Beyond identifying threats, the researchers propose that wastewater-based pathogen surveillance be used more widely in the country. They have provided a practical path forward for public health despite the infrastructural challenges in various regions of the country, according to the release from CSIR-Centre for Cellular and Molecular Biology (CCMB).

The reseachers utilised a shotgun metagenomics approach that looks into the details of bacterial genes. Through these genes, researchers can estimate how bacteria become resistant, it said.

Conducted between March 2022 and March 2024, the study analysed 447 samples from 19 sites across Delhi, Mumbai, Kolkata, and Chennai. The findings reveal a complex landscape - different bacteria are abundant in different cities, but they follow similar ways of resisting antibiotics.

This situation is called antimicrobial resistance (AMR) and is killing millions of people every year worldwide. Despite that, data on the local prevalence of AMR are largely missing in India. "We do not know which deadly bacteria around us might be the most resistant to available antibiotics, or if they all follow similar mechanisms to become resistant." Traditional lab culture methods do not offer such details.

"We have developed and validated a Standard Operating Procedure that allows for effective sample storage at 4°C for up to seven days without compromising data quality. The samples can be sent to common testing hubs, which suits resource-limited settings. A broader participation in wastewater-based surveillance will help to detect early outbreaks and track the spread of drug-resistant pathogens in real-time," said Dr Vinay K Nandicoori, Director, CSIR-CCMB.

Bacteria become resistant to antibiotics, thanks to certain genes. These genes either help the bacteria make stronger cell walls through which antibiotics cannot enter bacteria at all, or help the bacteria metabolise or throw out the antibiotic molecules from their cells or even destroy the antibiotic molecules. Bacteria can share these genes not only with their offspring but also with their neighbours.

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.

Antibiotics also belong to different chemical classes such as tetracyclines, beta-lactams and macrolides. The researchers also found that bacteria can share resistant genes against tetracyclines and beta-lactams far more easily than against macrolides.

Antimicrobial drugs like antibiotics kill bacteria and protect us from many deadly bacterial diseases. But bacteria are becoming resistant to antibiotics; antibiotics are not able to kill these microbes as effectively anymore.

- ANI