Scientists have pointed out a newly recognized gene which supplies bacteria immune to polymyxin antibiotics which are basically drugs often used as the last line of safe guard against infections and have the potential to be shared between different types of bacteria. The study has raised a great deal of concern regarding the transferable gene that could potentially make its way into infectious bacteria which are already highly resistant to drugs, thereby creating strains of bacteria immune to every drug in doctors’ arsenal.
According to a report by the BBC, the gene that has been labelled as mcr-1 has been recognized and found in patients and livestock in China; researchers say the resistance likely developed from the overuse of colistin on farm animals. A fifth of the animals tested by the scientists, as well as 16 human patients and 15% of raw meat were found to be susceptible. China happens to be the world’s largest user of the drug for veterinary and agriculture purposes, and its government is already looking into determining risks associated to the use of coliston.
The “antibiotic apocalypse” that has been explained in the report published online Nov. 18 in Lancet Infectious Diseases, means that in the near future, doctors will face “increasing numbers of patients for whom we will need to say, ‘Sorry, there is nothing I can do to cure your infection,’” according to commentary included in the study.
“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,” Timothy Walsh, a professor at University of Cardiff who worked on the study told the BBC.
Lab tests indicate that the plasmid could easily move between E. coli strains, metamorphosing polymyxin-sensitive strains into polymyxin-resistant ones. However, the plasmid had a relatively tougher time while moving between various bacterial species. The researchers had to coax the plasmid into other species by destroying bacterial cells with an electrical pulse to make their membranes more permeable—a technique called electroporation. The finding propounded that the plasmid may not easily move between species naturally.
“We needed to have definitive borders between antibiotics that are used in human medicine and those that are used in the veterinary sector,” said Timothy Walsh, a medical microbiologist from Cardiff University in Wales, and one of the authors of this paper who was also involved in the discovery of another dangerous plasmid-mediated resistance gene, NDM-1. “That mantra should be universal and strictly adhered to.”
Resistance to colistin has surfaced before. However, the major difference this time is the mutation has arisen in a way that is very easily shared between bacteria.
“The transfer rate of this resistance gene is ridiculously high, that doesn’t look good,” said Prof Mark Wilcox, from Leeds Teaching Hospitals NHS Trust. A major concern is that the new resistance gene will link up with others afflicting hospitals, leading to bacteria resistant to all treatment – what is known as pan-resistance.
“Hopefully the post-antibiotic era is not upon us yet. However, this is a wake-up call to the world.” said Professor Laura Piddock, from the campaign group Antibiotic Action, she also said the same antibiotics “should not be used in veterinary and human medicine”.