Drinking Water in New Delhi Contaminated With NDM-1

Seepage and drinking-water samples test positive for bacteria containing NDM-1 gene

THURSDAY, April 7 (HealthDay News) -- The New Delhi metallo-β-lactamase (NDM-1) gene has been found in drinking and seepage water in New Delhi, according to a study published online April 7 in The Lancet Infectious Diseases.

Timothy R. Walsh, Ph.D., from Cardiff University in the United Kingdom, and colleagues evaluated the prevalence of the NDM-1 gene (blaNDM-1) in drinking-water and seepage samples from New Delhi. They collected 50 drinking-water samples and 171 seepage samples from within a 12-km radius of central New Delhi, and compared them to 70 control samples from the Cardiff Wastewater. Bacteria were isolated and examined by polymerase chain reaction for blaNDM-1. Bacterial plasmid transfer frequency was assessed at three different temperatures.

The researchers found that the blaNDM-1 gene was present in two of the drinking-water samples and 51 seepage samples from New Delhi, and none of the samples from Cardiff. Bacteria positive for blaNDM-1 were grown from 12 seepage samples and two water samples. A total of 20 strains of bacteria were identified, which included 11 species in which blaNDM-1 had not previously been identified, including Shigella boydii and Vibrio cholerae. A total of 12 of the strains of bacteria carried blaNDM-1 on plasmids, and Aeromonas caviae and Vibrio cholerae isolates carried blaNDM-1 on chromosomes. The conjugative transfer rate was highest at 30 degrees Celsius, compared to 25 or 37 degrees.

"The presence of NDM-1 β-lactamase-producing bacteria in environmental samples in New Delhi has important implications for people living in the city who are reliant on public water and sanitation facilities," the authors write.

Two of the study authors disclosed financial ties to the pharmaceutical industry.

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