Scientists say they have found dangerous forms of bacteria in drinking water in New Delhi. These bacteria contain a gene that scientists call New Delhi metallo-beta-lactamase, or NDM-1. The gene is dangerous because it can make bacteria resistant to treatment with antibiotics.Researchers from the University of Cardiff in Britain led the study. They say they found the NDM-1 gene in bacteria in two out of fifty drinking water samples. They also found it in seepage water -- the water that children might play in on the streets. The gene was found in eleven kinds of bacteria, including those that cause cholera and dysentery. The researchers also reported finding the NDM-1 gene in bacteria collected from medical patients. These patients were from India and other South Asian countries as well as Europe and North America.The scientists estimate that about one hundred million Indians may be carrying bacteria with the gene as they travel. Timothy Walsh leads the NDM-1 research at the University of Cardiff. He says: "Wherever these people travel, they carry their normal flora with them, one hundred trillion bacteria. Therefore the ultimate consequence of this is it can spread worldwide." The United States government reported the presence of the NDM-1 gene in three people last year. All had been to India earlier for medical treatment.Experts say people can stay healthy even if they have bacteria with the gene in their body. The danger is if they get sick with disease-causing bacteria. The gene can make bacteria resistant to even the most powerful antibiotics. Antibiotics are the main treatment for bacterial infections.Indian officials say the water supply is safe. Vishwa Mohan Katoch, the director general of health services, says the bacteria do not usually cause a problem.However, officials in New Delhi are investigating. Timothy Walsh says he worries that the investigation will not employ the right study methods. He says he offered his team to help but Indian officials rejected the invitation. Professor Walsh also says it is time for the international community to force countries to follow World Health Organization guidelines for antibiotic use. The study appeared in the Lancet medical journal.

For VOA Special English, I'm Alex Villareal. To read and listen to more stories about health and for English teaching activities, go to voaspecialenglish.com.