The world is drawing closer to a “post-antibiotic era” after bacteria resistant to last-resort drugs are discovered in China. The mutation that made the bacteria resistant to the drug is called the MCR-1 gene, and spread resistance between various bacteria including E. coli. It remains to be seen how quickly the gene may spread more widely-but given that antibiotic resistance already kills thousands of people every year, it’s bad news however fast it happens.
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“These are extremely worrying results”, study author Jian-Hua Liu, a professor at South China Agricultural University in Guangzhou, China, said in a journal news release.
In particular, the scientists behind the study identified antibiotic-resistant DNA strands that were being transferred between Klesbsiella pneumoniae, which causes pneumonia, and Escherichia coli (better known as E. Coli), a leading cause of urinary tract infections.
Scientists found the bug was able to transfer its immunity to the drug to other strains via the mobile gene mcr-1.
“MCR-1 is likely to spread to the rest of the world at an alarming rate unless we take a globally coordinated approach to combat it. Coupled with the poor hygiene and habits of consuming raw or undercooked meat, the spread of resistance to Laos could create an environment where greater human exposure could occur than if meat was always hygienically handled and prepared”, she said. That suggests that the resistance originated in animals and then spread to people. “Until now, colistin resistance resulted from chromosomal mutations, making the resistance mechanism unstable and incapable of spreading to other bacteria”.
“In order to preserve colistin, as well as other lifesaving antibiotics, the use of antibiotics in animal-feed must be severely restricted in order to reduce the development of resistance among microorganisms which colonize the animals”, Polsky said.
The importance of selective pressure on this resistance gene becomes even more evident when considering the fact that China is one of the world’s largest users and producers of colistin for agriculture and veterinary use. Further tests were done on pigs in four Chinese provinces, and pork and chicken sold in 30 markets and 27 supermarkets across Guangzhou province. And two-thirds of farm animals generally – including cattle, sheep, pigs, turkeys and chickens – have ampicillin-resistant E.coli, according to a PHE report.
In an accompanying commentary, David Paterson and Patrick Harris, from the University of Queensland in Brisbane, Australia, say that the link between farm use of colistin and the presence of resistance in animals, food and human beings is now complete.
“One of the few solutions to uncoupling these connections is limitation or cessation of colistin use in agriculture”, they said.
Almost 12,000 tonnes of the drug are used annually in livestock production there, according to Marilyn Roberts, a researcher at the University of Washington School of Public Health in Seattle.
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“If MRC-1 becomes global, which is a case of when not if, and the gene aligns itself with other antibiotic resistance genes, which is inevitable, then we will have very likely reached the start of the post-antibiotic era”. Worryingly, the proportion of positive samples increased from year to year, they said, and mcr-1 was also found in 16 E.coli and K.pneumoniae samples from 1,322 hospitalized patients.
