A gene that makes bugs highly resistant to almost all known antibiotics has been found in bacteria in water supplies in New Delhi used by local people for drinking, washing and cooking, scientists said on Thursday.
The NDM 1 gene, which creates what some experts describe as "super superbugs", has spread to germs that cause cholera and dysentery, and is circulating freely in other bacteria in the Indian city capital of 14 million people, the researchers said.
"The inhabitants of New Delhi are continually being exposed to multidrug-resistant and NDM 1-positive bacteria", said Mark Toleman of Britain's Cardiff University School of Medicine, who published the findings in a study on Thursday.
A "substantial number" of them are consuming such bacteria on a daily basis, he told a briefing in London. "We believe we have discovered a very significant underlying source of NDM 1 in the capital city of India," he said.
NDM 1, or New Delhi metallo-beta-lactamase 1, makes bacteria resistant to almost all antibiotics, including the most powerful class, called carbapenems.
It first emerged in India three years ago and has now spread across the world. It has been found in a wide variety of bugs, including familiar pathogens like Escherichia coli, or E. coli.
No new drugs are on the horizon for at least 5-6 years to tackle it and experts are concerned that only a few major drug companies, such as GlaxoSmithKline and AstraZeneca, still have strong antibiotic development programs.
Mr. Toleman's study, carried out with Cardiff University's Timothy Walsh and published in The Lancet Infectious Diseases journal, investigated how common NDM 1-producing bacteria are in community waste seepage - such as water pools or rivulets in streets - and tap water in urban New Delhi.
The researchers collected 171 swabs from seepage water and 50 public tap water samples from sites within a 12 kilometre radius of central New Delhi between September and October 2010.
The NDM 1 gene was found in two of the drinking-water samples and 51 of seepage samples, the researchers said, and bacteria positive for NDM 1 were grown from two drinking-water samples and 12 seepage samples.
"We would expect that perhaps as many as half a million people are carrying NDM 1-producing bacteria as normal (gut) flora in New Dehli alone," Mr. Toleman said.
Experts say the spread of superbugs threatens whole swathes of modern medicine, which cannot be practised if doctors have no effective antibiotics to ward off infections during surgery, intensive care or cancer treatments like chemotherapy.
In a commentary about the findings, Mohd Shahid from Jawaharlal Nehru Medical College and Hospital in Uttar Pradesh, India, said global action was needed.
"The potential for wider international spread of ... NDM 1 is real and should not be ignored," he wrote.
The World Health Organization has designated April 7 as World Health Day and under the slogan "No action today, no cure tomorrow" it is campaigning about the risks of life-saving antibiotics losing their healing power.
"We are at a critical point in time where antibiotic resistance is reaching unprecedented levels," said Zsuzsanna Jakab, the WHO's regional director for Europe.
"Given the growth of travel and trade in Europe and across the world, people should be aware that until all countries tackle this, no country alone can be safe."