Researchers have discovered a new gene in E. coli that makes the bacteria resistant to colistin, an antibiotic of last resort.
Their findings are detailed in a study in mBio.
This is the third such gene discovered by researchers. When the first colistin resistance gene, mcr-1, emerged in an E. coli strain, it attracted "substantial attention worldwide," according to the mBio study. Indeed, media heralded the bacteria as the "super" superbug.
A second colistin resistance gene, mcr-2, has also been discovered.
The new gene, mcr-3, was discovered when a colistin-resistant E. coli strain from a pig intestine tested negative for mcr-1 and mcr-2, the two previously known genes that conferred colistin resistance.
The results "suggest the likelihood of a wide dissemination of the novel mobile colistin resistance gene mcr-3" among other bacteria.