New Delhi: A new online study on the emergence of the superbug, which British researchers had traced to India in 2010, has said the antibiotic resistant gene was constructed very recently, challenging Indian health authorities` contention that it has existed in the environment forever.
Authored by four British researchers including Timothy Walsh of Cardiff University, who discovered the superbug in August 2010, the new study says the fast spreading NDM-1 gene (New Delhi Metallo B Lactamase) came into existence after a very recent fusion between two previously existing antibiotic resistant genes.
With this conclusion, the researchers have challenged the stand of Indian health authorities who have been maintaining that drug-resistant pathogens such as the superbug have existed forever and can be found in any country.
"Our study is unequivocal evidence that NDM-1 is a chimeric gene that has arisen by the fusion of a pre-existing MBL gene with another gene called aph46 which was first
reported only in 1988. NDM-1 gene was likely constructed in the bacteria called Acinetobacter baumanii.
And the first European isolate of this bacteria containing NDM-1 gene was collected recently in Germany," says the study published in the latest online edition of the American journal - "Antimicrobial Agents and Chemotherapy".
In support of their new findings, the researchers say "we have shown that NDM-1 is a chimera and freak and a result of genetic fusion between two previous antibiotic-resistant
genes. It is likely that NDM-1 was constructed very recently and therefore any ideas that suggest it is found everywhere and has been around for ever are found-less."
The study is targeted at India, considering the Health Ministry had in August 2010 rejected the Lancet Report which said that drug-resistant superbugs that could cause multiple organ failure had been traced to India.
The study conducted by Indian and British researchers, including Timothy Walsh, had then named the new gene as NDM-1 after New Delhi because it was found in patients in South Asia and Britain, who had previously been hospitalized in Indian hospitals.
The Indian health authorities had then vehemently denied the existence of any kind of bacteria in Delhi hospitals. The Directorate General of Health Services had opposed naming of the bacteria after New Delhi.
The National Centre for Disease Control and the Indian Council of Medical Research had also flayed the Lancet report on the superbug.
However, India has objected to the naming of the gene after New Delhi though Timothy Walsh who was in India last year to attend the Global Conference on Antimicrobial
Resistance defended such naming.
NDM-1 gene is an enzyme carried by certain bacteria and has been found top erode the effectiveness of even the most powerful group of antibiotics which are called carbapenems.
In the latest study, researchers say, "We have previously identified NDM-1 genes in a broad range of gram negative bacteria isolated from the New Delhi environment including the serious pathogens like Shigella boydii and Vibrio cholera which cause gastric infections. In the continuing absence of any new antibacterials effective against ram negative pathogens, the spread of NDM-1 producing strains is a cause for significant concern."
The new study concludes, "Our studies indicate that the fusion event which resulted in the construction of drug resistant NDM-1 gene was a very recent event in line with what
is known about the emergence of NDM-1."