By Abdullahi Lukman
Sewage flowing through Indian cities is emerging as a major reservoir for antibiotic-resistant bacteria, with wastewater systems helping to spread resistance to commonly used drugs, according to a new research published in Nature.
The study found that antibiotic residues from hospitals, households and other sources are entering drains and sewers, creating conditions that allow bacteria to develop and share resistance genes.
Scientists warn this process is weakening the effectiveness of widely used antibiotics, including azithromycin, and extending antimicrobial resistance beyond hospitals into rivers and communities.
Researchers reported that untreated sewage and hospital waste are flowing into major waterways such as the Yamuna River, exposing downstream populations to resistant pathogens.
In some locations, antibiotic concentrations in sewage were high enough to promote genetic exchange among bacteria, accelerating the spread of resistance.
The findings show that antibiotic resistance genes were more abundant in sewage than in hospital samples for some drug classes.
Aminoglycoside resistance genes, for example, were found to be about 50 percent more prevalent in sewage, suggesting additional inputs from agriculture, poultry and fisheries.
Sampling conducted in Faridabad revealed that bacteria in community sewage shared genetic profiles with pathogens responsible for hospital-acquired infections worldwide between 2019 and 2023.
These included strains of Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii, indicating that clinically dangerous bacteria are circulating through urban wastewater.
Beyond individual cities, the researchers analysed hundreds of sewage samples collected from six states between June and December 2023.
They detected residues of 11 antibiotics across seven drug classes, with kanamycin and azithromycin among the most frequently identified.
In total, 170 resistance genes linked to 16 antibiotic classes were found.
Laboratory testing showed the scale of the threat: nearly 94 percent of tested bacterial isolates were resistant to more than 10 antibiotics.
Genome sequencing confirmed resistance genes across multiple bacterial families, including species known to cause severe human infections.
The researchers said the results demonstrate a clear link between antibiotic concentrations in sewage and the presence of drug-resistant pathogens, warning that wastewater systems are acting as reservoirs for extensively drug-resistant bacteria.
Experts not involved in the study said the findings strengthen the case for environmental surveillance of antimicrobial resistance, particularly in countries with limited regulation of antibiotic use.
The authors also called for an India-specific resistance gene database to better track how resistance develops and spreads within the country’s unique ecological conditions.
