Mcr-9 May 2026

Stay vigilant. Wash your hands. And support antibiotic research.

Colistin works like a sledgehammer: it punches holes in the bacterial cell wall. The mcr-9 gene instructs the bacteria to add a chemical modification to their cell surface. This modification acts like a patch, making the surface less sticky to colistin. The result? The antibiotic bounces off. The scary headlines about mcr-1 were loud and clear. mcr-9, however, has been flying under the radar. Here is why that is dangerous: Stay vigilant

If you follow infectious disease news, you’ve probably heard of the "nightmare bacteria" or the "panic germ." For years, scientists have been sounding the alarm about a specific gene called mcr-1 . Why? Because it makes bacteria resistant to colistin —the antibiotic we hold in reserve as the "last resort" for multi-drug resistant infections. Colistin works like a sledgehammer: it punches holes

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. The result