The woman harboring E. coli resistant to colistin did not know it, and it’s only luck that we do. Her doctor would have never prescribed that last-resort antibiotic for a routine urinary tract infection-it can cause serious kidney damage. But her doctor did take a urine sample, which ended up at the Walter Reed National Military Medical Center, where researchers had recently started testing for colistin resistance. The test came back positive. Then the came scary headlines about a new superbug in the US. Superbugs are bacteria with genetic mutations that let them survive humanity’s harshest weapons in germ warfare: antibiotics. The gene behind this E. coli’s colistin resistance is called mcr-1.

A superbug that cannot be treated with even the strongest of last-resort antibiotics has just been reported for the first time in the United States. After various antibiotics failed to kill the bacteria, doctors attempted to use Colistin - a last-resort medication used when other methods fail - and not even that has worked, according to CNN. Tom Frieden, MD, MPH, director of the Centers for Disease Control and Prevention (CDC), made the announcement on May 27 that they are looking for other instances of the superbug.