A bacteria that carries a transmissible gene resistant to carbapenems, one of the most important classes of antibiotics used against multidrug resistant bacteria, has been found in animals in the United States.
In hospitals, carbapenem antibiotics are used as a last line of defense against bacterial infections that are difficult to treat, but these drugs are not allowed for veterinary use as a precautionary measure to reduce the likelihood of antibiotic resistance developing among animals, which could spread to humans.
Carbapenem-resistant bacteria have already been identified in livestock in Europe and Asia. There had been no signs of a resistance problems on farms in the United States, but after a period of five months of screening a pig farm in 2015, researchers reported the presence of carbapenem resistance in U.S. livestock.
Antibiotic Resistance In Food Animals
Thomas Wittum, from the Ohio State University, said that the case could be a rare and unusual occurrence. Nonetheless, he raised concern since it involved food animals whose meat will someday get into the food supply market and sold as fresh pork products.
The researchers said that none of the pigs that were scheduled for slaughter carried the mutant bacteria albeit the research team has since recovered the germ in both sows and piglets.
"We found no evidence that these organisms were entering the food supply, but that is the concern: that it could happen on this or other farms," Wittum said. "We need more research to really understand that risk."
Spread Of Mutant Gene In The Pig Farm
None of the pigs were sick, but the mutant gene should not have been present on the farm in the first place. The researchers acknowledged that they do not have a clear idea on how it managed to get into the farm.
"The spread of this particular resistant strain on this farm may be related to antibiotics used to treat sick pigs, for the same reason that resistant bacteria like these are present in human hospitals because of the way we treat sick people with antibiotics," Wittum said.
The carbapenem-resistant gene, which was reported in the study published in the journal Antimicrobial Agents and Chemotherapy, is called bla IMP-27. It is carried by plasmids, small independent pieces of DNA that can easily move from one bacterium to another across species.
Superbugs pose potentially fatal health threats. The antibiotic-resistant germ known as carbapenem-resistant Enterobacteriaceae, or CRE, is particularly dangerous because once it gets into the bloodstream and cause infection, the bacteria can kill half of its victims.