Mcr-9

Most resistance genes are loud. If you test a bacteria carrying mcr-1 in a standard lab, it will happily grow in a petri dish laced with colistin. But mcr-9 is often silent in standard tests. The gene might be present, but the bacteria doesn't always "turn it on" until it is under threat. This means a hospital lab could test a bacteria, find it "susceptible" to colistin, and prescribe the drug—only for the bacteria to activate mcr-9 mid-infection and suddenly become resistant.

But just when we started getting a handle on tracking mcr-1 , evolution threw us a curveball. Meet its stealthier, harder-to-detect cousin: . What is mcr-9? In the simplest terms, mcr-9 is a gene. It belongs to the mobilized colistin resistance (mcr) family. Like other members of this family (mcr-1 through mcr-8), its primary job is to protect bacteria from colistin. Most resistance genes are loud

Stay vigilant. Wash your hands. And support antibiotic research. The gene might be present, but the bacteria