Monday, January 25, 2016

MCR-1 gene: Update


I have previously blogged about colistin resistance factor in a plasmid that has had the world turn attention (Read earlier posts here and here). This discovery signalled that we are loosing out on antibiotics. Colistin is one of the last resorts against pan drug resistant gram negative bacteria. Resistance to this drug would be essentially a grave problem. It is generally agreed that Colistin is not the only drug, there are a couple of other options in case of such infections but the arsenal is very limited.

Ever since the first identification report was published, most of the countries have looked for the gene sequence in their strains and databases and there has been aggressive reporting of the findings. This is in part, a global effort. I need to stress here that the media reporting these as first instance is totally wrong. The gene has been described earlier in chromosomes of resistant organisms. The highlight of this issue is, now it is a plasmid which makes it more mobile. In other words, unlike the earlier known version, this is moving through different strains.

Fig 1, is a representation of the discovery of MCR-1 in bacterial isolates. The samples include from anything that can be imagined- human sample, commercially available meat, animals etc. 

Fig 1: Map of MCR-1 gene detected. Data as on 15 January 2016. Source
It has been established that this rise in antibiotic resistance is due to the heavy use of antibiotics in livestock. Interestingly, despite several earlier warnings the antibiotic sale has shot up by about 23% over the last 5 years, a majority of which is going into the livestock use.

It remains to be seen what is the true extent of spread of MCR-1. However, experts agree that it has already spread and some suggest that with surveillance and molecular evidence we maybe able to see more regions.

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