Aligarh (UP)

Researchers at the Interdisciplinary Biotechnology Unit of Aligarh Muslim University have identified a new multidrug-resistant bacterial genome in wastewater flowing through Aligarh city, raising concerns over the growing threat of antibiotic resistance in densely populated urban areas.

The findings, published in the April edition of the scientific journal 'Molecular Biology Reports', are based on a long-term study by a team of scientists led by Asad Ullah Khan, Shamsi Khalid and Absar Talat, who have been tracking the evolution of antibiotic resistance genes (ARGs) for over a decade.

According to the study, genome sequencing of a bacterial isolate, identified as 'AK 633' from a major city drain revealed the presence of a rare "mosaic plasmid" carrying the NDM-7 gene, which is associated with resistance to multiple antibiotics.

In microbiology, plasmids are small DNA molecules inside bacteria that can transfer genetic material, including drug-resistance traits, from one bacterium to another. A "mosaic plasmid" refers to a plasmid formed through genetic recombination, enabling it to carry resistance traits from different bacterial sources.

The researchers said the NDM-7 gene belongs to the New Delhi Metallo-beta-lactamase (NDM) family of resistance genes, which make bacteria resistant even to "last-resort antibiotics" such as carbapenems that are often used when other antibiotics fail.

The study noted that the sequencing of AK 633 pointed to the role of the plasmid 'p1550' in the possible global spread of high-risk antibiotic-resistant bacterial clones.

Talking to PTI, researcher Asad Ullah Khan said the findings underscore the urgent need for a wider national surveillance and awareness programme to monitor and contain the growing menace of drug-resistant bacterial genomes.

He said antibiotic resistance has emerged as a major public health challenge worldwide and pointed to untreated waste disposal, particularly hospital waste, and poor drainage management as important contributing factors.

Khan also stressed the need for vigilance during drain-cleaning operations in urban areas.

"Very often after drains are cleaned, the sludge is left on the roadside for long periods instead of being immediately removed. Such practices can contribute to the spread of resistant organisms," he said.

According to the researchers, genotypic analysis -- the study of the genetic composition of bacterial isolates -- is essential to understand how resistance genes spread between bacteria in community and hospital settings.

Khan said at least 94 variants of NDM genes have so far been identified globally, many of which are increasingly being found both in hospitals and in the community.

"These are among the main causes of resistance against last-resort antibiotics," he said.

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The researchers noted that while similar work is being carried out in a limited number of laboratories in India, a much larger scientific and public health effort is needed to combat the growing threat posed by multidrug-resistant bacterial genomes.