Indian researchers have isolated a strain of E.Coli bacteria, carrying a new gene (mcr -1), described previously as ‘truly pan-drug resistant’. It is resistant to the last mile antibiotic the human race currently has access to —colistin.
While colistin resistance had already been detected in India, it existed thus far only as mutations in the chromosomal/genetic path. Now, mutations do not spread from patient to patient. With mcr-1, however, the gene is found in the plasmid medium, a small DNA molecule outside of the chromosomal DNA, meaning the infection can spread in hospitals, and the community.
In a letter published in the Clinical Infectious Diseases, in the Oxford Journals group, the authors Mohit Kumar (of Shiv Astha Hospital, Haryana) et al, note: “The emergence of plasmid-mediated colistin resistance heralds the breach of the last group of antibiotics, polymyxins.”
“This is an important turning point in the country. While we have already recorded colistin resistance, mcr-1 is an entirely different story all together. It is not self limiting, and can spread in the community,” says Abdul Ghafur, Coordinator, Chennai Declaration, which attempted to set a road map to tackle antimicrobial resistance in the country.
NDM1 superbugTo explain further the implications, Dr. Ghafur draws a parallel with the NDM1 superbug that was identified in an article in the Lancet in 2010. “At that point, it was estimated to be present between two and three per cent in the bacterial population. Now it has grown exponentially.”
Karthikeyan Kumaraswamy, the researcher whose publication on NDM1 unleashed a virtual storm in the health sector, agrees with Dr. Ghafur about the growth of the NDM1: “We identified the NDM1 from a sewage sample, but today we are seeing so many patients presenting with NDM1 literally on a daily basis.” However, he adds that no plasmid-mediated colistin resistance has emerged in his research as yet. Mcr-1 has already been reported in half a dozen countries, and the indications are the same as colistin resistance, as is the treatment protocol. “The thing is we must realise that clinical practice depends on colistin. The next antibiotic will probably be ready in a couple of years, and that is of concern to us,” he adds.
V. Ramasubramaniam, consultant, Infectious Diseases, Apollo Hospitals, takes a pragmatic approach. “Whenever an antibiotic is used/overused/ misused, resistance develops. A mix of bacteria enters the sewage, contaminates drinking water and enters the gut of a healthy individual, making him/her resistant to those bugs. This resistance moves from one level to another. Mcr-1 is therefore, inevitable.”
