Where did the gene come from?
The birthplace of the bacterial antibiotic resistance gene of the "last reserve" has been found
Sergey Vasiliev, Naked Science
Antibiotics of the polymyxin group (including colistin) belong to the drugs of the "last reserve", to which doctors resort only in cases when other means no longer give results. They try to minimize their use: firstly, because of dangerous side effects, and secondly, in order not to give bacteria an extra chance to develop resistance. But this does not help much: a few years ago, the MCR-1 plasmid was discovered, carrying the colistin resistance gene (mcr-1) and transmitted from cell to cell. It does not give microbes absolute protection, but forces doctors to prescribe large, "horse" doses of an antibiotic to patients.
The main accusations in this regard are made against farmers in China and India, who use antibiotics thoughtlessly, massively adding them to food for livestock. China is also indicated by the new work of a large group of scientists led by Francois Balloux from University College London. Their paper analyzing the spread of the mcr-1 gene is published in the journal Nature Communications.
Scientists have identified a total of 457 colistin-resistant bacterial strains isolated from humans and animals, among others. "The speed at which the global spread of mcr-1 is simply shocking,– says Professor Ballou. "I wouldn't be surprised if we find the emergence and spread of genetic elements that give greater resistance to colistin than mcr–1, which will only aggravate the situation."
Strain detection statistics,
resistant to colistin / © UCL
Genetic analysis showed that the plasmid could have appeared back in 2005 on one of the pig farms, and then began to spread around the world. Ten years later (scientists first noticed MCR-1 in 2016), resistant microbes were found on all inhabited continents except Australia. These rates amazed the researchers. "We cannot specify exactly all the ways of its distribution," the authors of the work say. – But it can be assumed that other antibiotic resistance genes can be transmitted in the same ways and at the same rate. <...> This is a global problem that requires a coordinated international response."
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