Scientists have discovered a third instance of a so-called superbug, raising concerns about its spread.
Researchers found E. coli bacteria that is resistant to one of the strongest antibiotics available in a pig at an Illinois slaughterhouse.
The worry is that this resistance will spread to bacteria that are also resistant to other drugs, effectively making bacteria immune to antibiotics.
The gene in question first popped up in China last fall. In the U.S., it was first detected in a pig in March and also in a Pennsylvania woman.