Will Antibiotic Defence Fail As Superbugs Breach The Barrier?
Researchers from South China Agricultural University and China Agricultural University have identified a new gene that makes bacteria highly resistant to humans' antibiotic defense against illnesses. They came across clues that showed the gene's potential to easily spread to all types of bacteria, according to HNGN.
Called mcr-1, the gene makes bacteria resistant to polymyxins, which is a group of antibiotics that is usually used against "multi-drug resistant gram-negative bacteria".
It has been found to be rampant among Enterobacteriaceae isolated from patients and animals in south China. The mcr-1 gene was also discovered in plasmids, which can be quickly shifted from one plant to another.
This has been an "extremely worrying" discovery for the scientists, as the polymyxins, which is the final line of antibiotics, can lead to chromosomal mutations breaking up the resistance of gram-negative bacteria against drugs -- until now.
"Our results reveal the emergence of the first polymyxin resistance gene that is readily passed between common bacteria such as Escherichia coli and Klebsiella pneumoniae, suggesting that the progression from extensive drug resistance to pandrug resistance is inevitable," study author Professor Jian-Hua Liu said in a press release.
The gene was identified in E. coli strains isolated from a pig in Shanghai. Scientists started gathering samples from pigs in four provinces. Other samples were gathered from chicken and pork in 30 markets and 27 supermarkets across Guangzhou, while bacterial samples were collected from patients in Guangdong and Zhejiang hospitals.
"The mcr-1 gene was found in E. coli isolated from 166 of 804 animals and 78 of 523 raw meat samples. It was also detected in E. coli and K. pneumoniae isolated from 16 of 1,322 patients," according to HNGN.
Scientists found that the mcr-1 gene has high rates of being copied and transferred among E. coli strains, along with the potential to cause K. pneumoniae and Pseudomonas aeruginosa, hinting that it could spread also to human pathogens.
Study author Professor Jianzhong Shen explained that the resistance to polymyxin resistance might have started in animals and got transferred to humans. He added that the mcr-1 gene might have developed due to the "increasingly heavy use of colistin in agriculture."
"The emergence of mcr-1 heralds the breach of the last group of antibiotics," the authors said. "Although currently confined to China, mcr-1 is likely to emulate other resistance genes such as blaNDM-1 and spread worldwide. There is a critical need to re-evaluate the use of polymyxins in animals and for very close international monitoring and surveillance of mcr-1 in human and veterinary medicine."
The study was published in the online Nov. 18 issue of The Lancet Infectious Diseases.