Initially thought to be a danger only in hospitals, bacteria with the antibiotic-proof gene than can be horizontally transferred to other bacterial strains has been found in New Delhi's tap water network by researchers from the University of Cardiff led by Dr. Timothy Walsh as reported in the Lancet Infectious Diseases website.

The enzyme that causes this almost bullet-proof resistance to antibiotics is called NDM-1 (New Delhi metallo-beta-lactamase-1) because it was first described in a patient that acquired an infection from India. Indian scientists have since demanded that such 'geographic names giving' be abandoned and replaced by 'scientific names giving'. PCM (Plasmid-encoding Carbapenemase-resistant Metallo-B-Lactamase) has since been proposed to replace NDM-1.

But PCM or NDM-1, this is a worrisome piece of genetics because it is not very particular about the host bacteria it latches on to. In the Indian water samples gathered by Walsh and his team, NDM-1 was found in 11 different bacterial species. Aside from Klebsiella and Citrobacter, which are associated to hospital-associated infections they also identified it in E. coli, the stomach bug found in almost everyoneas well as in Shigella, which causes dysentery. But the scariest discovery is its presence in the germ that causes cholera because it makes an already nasty bug practically untreatable.

Walsh's study of India's water supply was prompted by observations that contradicted initial theories about how bacteria laden with this enzyme had been contracted. Thought to be acquired from being admitted to an Indian hospital, cases with the same type of bugs were then also observed in patients that had never been to hospital and thus were acquiring it through some other means.

The results were scary. From Sept 26 to Oct 10, 2010, Walsh and his team collected 171 seepage samples and 50 tap water samples from New Delhi. As a control group, 70 sewage effluent samples were taken from Cardiff Wastewater Treatment Works. In two of the 50 drinking water samples, bacteria with NDM-1 was detected as it was in 51 of 171 seepage samples from New Delhi. Bugs with the gene was not found in any sample from Cardiff.

The study said that 20 NDM-1-positive strains of bacteria were present in the samples, including the opportunistic Enterobacteriaceae Citrobacter freundii, E coli, and K pneumoniae, which commonly carry NDM-1 in hospitals in India and elsewhere, as well as the pathogenic species Shigella boydii and V cholerae, and Aeromonas caviae (a probable cause of gastroenteritis). Non-fermentative Gram-negative bacteria not previously reported to carry NDM-1 were also present, comprising Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas pseudoalcaligenes, Pseudomonas oryzihabitans, Sutonella indologenes, Stenotrophomonas maltophilia, Achromobacter spp, and Kingella denitrificans.