Rare Superbug Identified On U.S. Pig Farm

A rare superbug gene has been identified on U.S. pig farm. Researchers, led by Thomas Wittum, chair of the veterinary medicine team at The Ohio State University, discovered bla IMP-27, an extremely rare gene and say the discovery could suggest that raw meat could carry the superbug into the human population.

No pigs scheduled for slaughter carried the problematic gene and the pig herd has been a closed herd since the 1960's. Researchers believe the gene must have been carried into the herd, though they are not sure how.

The gene gives bacteria the ability to resist the effects of carbapenems, a class of "last-resort" antibiotics. Researchers discovered several different species of the bacteria on the farm, which suggests the gene has been passed around already.

A single sample was discovered carrying bla IMP-27 originally, which led Ohio State researchers to look more closely at the moderate-sized, family-run operation. Among the 1500 sows on the farm, researchers found several species of bacteria, including E. coli and Enterobacteriaceae. There were several bacteria found that were resistant to more than one type of antibiotic.

Wittum told NBC News that the pigs were never given any carbapenem antibiotics and they didn't receive antibiotics to promote their growth. However, they did receive a dose of antibiotics at birth, and for males a second dose at castration.