Superbug turns up in Delhi drinking water

A gene that makes bacteria highly drug-resistant has been found in drinking water supplies in New Delhi, scientists say.

NDM-1 or New Delhi metallo-beta-lactamase 1, makes bacteria resistant to almost all antibiotics. Since it was first identified in 1998, infections have occurred in Britain, Canada, Australia, the U.S. and Sweden.

The gene was found intwo of the 50 drinking water samples and 51 of 171 street samples.

It was also found in 11 different types of bacteria not previously reported, including those that cause dysentery and cholera, Timothy Walsh of Cardiff University in the UK and his co-authors said inThursday's issue of the journal Lancet Infectious Diseases.

The samples were taken between September and October 2010 and tested for the presence of the NDM-1 gene. Bacteria isolated from the water samples were also tested for susceptibility to antibiotics.

As a comparison, samples were also taken from a water treatment centre in Cardiff. No NDM-1 genes were found in those.

The rate at which the gene was copied and transferred to other bacteria was highest at 30 C, a temperate that falls within the city's daily range from April to October. The time period includes monsoon season, which could potentially disseminate resistant bacteria, the researchers said.

Oral-fecal transmission of bacteria is a problem worldwide, particularly in places with poor sanitation. It represents a serious problem in India, where 650 million citizens do not have access to a flush toilet and even more probably do not have access to clean water, according to the study.

"International surveillance of resistance, incorporating environmental sampling as well as examination of clinical isolates needs to be established as a priority and cover Pakistan and Bangladesh, because these are also source countries for exported cases," the study's authors concluded.

Indian health officials called the study "unsupported," citing a random sample of nearly 2,000 women in a New Delhi hospital which they said showed no sign of the NDM-1 gene.

"We know that such bacteria with genes are in the atmosphere everywhere," said V.M. Katoch, director-general of the Indian Council of Medical Research. "This is a waste of time," he said. "The study is creating a scare that India is a dangerous country to visit. We are condemning it."

In a commentary accompanying the study, Mohd Shahid from Jawaharlal Nehru Medical College and Hospital in Uttar Pradesh, India warned "the potential for wider international spread of plasmids encoding NDM-1 is real and should not be ignoredcoordinated, concrete, and collective efforts are needed, initially to limit their widespread dissemination, and finally to combat this emerging threatening resistance problem."

The emergence of NDM-1 is "worrisome" but it is difficult to forecast what could happen, said Guenael Rodier, director of communicable diseases at the World Health Organization's office in Copenhagen. He noted resistant strains can mysteriously disappear.

The European Union paid for the study.