NDM-1 circulating in water samples in New Delhi

Walsh TR. Lancet Infect Dis. 2011;doi:10.1016/S1473-3099(11)70059-7.

Researchers from the United Kingdom have identified New Delhi metallo-beta-lactamase-1 circulating in community water samples in New Delhi. Future steps toward international surveillance of resistance should, therefore, include sample carriage in both residents and travelers in South Asia, according to Timothy R. Walsh, PhD, and colleagues.

Walsh, professor in the department of infection at Cardiff University, in the United Kingdom, and colleagues conducted an environmental point prevalence study to measure the incidence of New Delhi metallo-beta-lactamase-1 (NDM-1) in samples of drinking water collected from sites within a 12 km radius of central New Delhi. Between Sept. 26 to Oct. 10, 2010, 171 seepage samples and 50 samples of tap water were collected and compared with 70 control samples of sewage effluents from the Cardiff Wastewater Treatment Works in Tremorfa, Wales.

NDM-1 was detected in 51 seepage samples and two drinking-water samples compared with none of the control samples from Wales. Eleven species of NDM-1 bacteria not previously reported were found in 12 seepage samples and two water samples in New Delhi. All seepage samples grew bacteria resistant to cefotaxime, including Enterobactiaceae, according to the researchers.

Of the 20 strains that tested positive for NDM-1, researchers detected E. coli, K. pneumonia, Shigella boydii, Aeromonas caviae, and V. cholera. Bacteria that were present but not previously reported to carry NDM-1 included, P. aeruginosa, P. putida, P. pseudoalcaligenes, P. oryzihabitans, and K. denitrificans.

“The results of this study suggest widespread environmental contamination and are in keeping with the facts that not all of the UK or European patients with NDM-1-positve bacteria who had visited India were admitted to hospital there and that many patients from Chennai who had NDM-1-positive clinical isolates had no recent history of hospital admission,” the researchers wrote. “Rather than being a purely nosocomial problem, bacteria with this resistance seem to be circulating in the community; thus they may be imported into hospitals with admitted patients and probably enriched within the gut flora when these patients, for whatever reason, receive antibiotic treatment or prophylaxis.”

Disclosure: This research was funded by the European Union.

James Hughes, MD

Antimicrobial resistance is a local, national, and global problem, as underscored by its selection by the World Health Organization as the theme for this year’s World Health Day. We are faced with increasing resistance at a time of a dramatically decreasing rate of development of new antimicrobial drugs; the slogan for World Health Day appropriately is, “No action today, no cure tomorrow.” The emergence of the New Delhi beta-lactamase gene which confers resistance to a broad range of beta-lactam antibiotics has recently been reported from a number of countries on five continents. Initial reports involved infections in India, Pakistan, and the United Kingdom; infections in the UK were associated with medical tourism in India, reminding us once again that microbes do not respect international borders. The recent report of detection of the NDM-1 gene in tap water and surface water samples from the megacity New Delhi highlights the potential for environmental contamination to contribute to dissemination of this gene and organisms containing it to the exposed population, which includes the poorest of the poor. At a time when approximately 900 million people worldwide lack access to water from a safe source and approximately 2.5 billion lack access to adequate sanitation, the potential for further rapid dissemination of this gene and organisms containing it should be obvious. These findings reinforce the urgency of improving surveillance of drug-resistant infections, promoting judicious antimicrobial usage, conducting further epidemiologic, microbiologic, and environmental research to better document this problem and assess its implications, and addressing the global water and sanitation crisis.

– James M. Hughes, MD

Infectious Disease News Editorial Board member

Disclosure: Dr. Hughes reports no relevant financial disclosures

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