A new class of bacteria resistant to almost all antibiotics is spreading from South Asia, says a new study conducted by a joint research team of Cardiff University and the University of Madras.

The new drug-resistant superbugs, which have reportedly spread to Britain, contain a gene called NDM-1 that makes them impervious to drugs.

The NDM-1 or New Delhi metallo-beta-lactamase-1 gene was first identified last year by Cardiff University's Timothy Walsh in two types of bacteria, viz., the Klebsiella pneumoniae and Escherichia coli, from a Swedish patient admitted to an Indian hospital.

The bacteria containing NDM-1 gene are resistant even to carbapenems, a group of antibiotics often reserved as a last resort for emergency treatment for multi-drug resistant bugs, reports said.

In the new study, led by Walsh and Madras University's Karthikeyan Kumarasamy, researchers checked hospital patients with suspect symptoms to determine how common the NDM-1 producing bacteria were in South Asia.

They found 44 cases or 1.5 percent of those screened in the south Indian state of Chennai, and 26 (eight percent) in the norther state of Haryana infected with the resistant bugs.

The researchers also detected the superbug in Bangladesh and Pakistan, as well 37 cases in Britain. "India also provides cosmetic surgery for other Europeans and Americans, and it is likely that NDM-1 will spread worldwide," said the study, published in the British medical journal The Lancet.

Most commonly, NDM-1 gene was found in E. coli and K. pneumoniae, and ressitant to all antibiotics except two, tigecycline and colistin. The authors said the NDM-1 gene was found on DNA structures, called plasmids that can be easily copied and transferred between bacteria, giving the bug "an alarming potential to spread and diversify".

"Unprecedented air travel and migration allow bacterial plasmids and clones to be transported rapidly between countries and continents," mostly undetected, they said.

The emergence of these new drug-resistant bacteria could become a serious global public health problem as the threat shifts toward a broad class of bacteria including those armed with the NDM-1 gene known as Gram-negative. "There are few new anti-Gram-negative antibiotics in development, and none that are effective against NDM-1," the study said.