CRE superbug found on pig farm in U.S.

CRE Superbug Found On U.S. Farm For First Time: ‘Widespread’ Antibiotic Use Questioned

The CRE superbug has been found on a farm in the United States, triggering a five-month investigation, according to Modern Farmer. Less than a week after 700 hospitals were penalized for superbug infections comes word that a pig farm had a positive test for CRE in 2015. According to the Centers for Disease Control, Carbapenem-resistant Enterobacteriaceae, more commonly known as CRE, are bacteria that are resistant to the antibiotics that are also known as the “last line of defense.”

“Carbapenems are a group of antibiotics that are usually reserved to treat serious infections, particularly when these infections are caused by germs that are highly resistant to antibiotics. Sometimes carbapenems are considered antibiotics of last resort for some infections. Some Enterobacteriaceae can no longer be treated with carbapenems because they have developed resistance to these antibiotics (i.e., CRE); resistance makes the antibiotics ineffective in killing the resistant germ. Resistance to carbapenems can be due to a few different mechanisms.”

Hospital, a normal source for CRE superbug infections
The CRE superbug is normally found in hospitals. [Image by Christopher Furlong/Getty Images]

This is the first time the CRE superbug has been found on a U.S. farm, though it has also been found on farms in France, Germany, and China among others. A research team from Ohio State University, led by Thomas Wittum, chair of veterinary medicine, spent five months researching the case because it was so unusual. Wittum explained that the superbug was normally found in hospitals until the discovery on the farm.

The name and location of the farm have not been disclosed, but the details of the case were published in the journal Antimicrobial Agents and Chemotherapy. What is known is that the presence of the CRE superbug was unexpected because the farm is a “closed-herd” farm, and has been so since the 1960s. The superbug infection was located in the farrowing barns, which is where nursing sows and piglets are isolated for the protection of the young. Since the farm is closed herd, investigators were pressed to find an answer for how the CRE was introduced.

The investigators swabbed pigs, the pens, and the equipment at the farm. They also took fecal samples. Wittum pointed out that none of the pigs that were ready for slaughter tested positive. So far, there are no known transmissions of the CRE superbug through meat, but it remains a health concern.

Dr. Sumanth Gandra with the Centers for Disease Dynamics, Economics & Policy believes that it is a “hypothetical possibility that the superbug could be transmitted through raw or under-cooked meat. Wittum acknowledged that the CRE superbug find could be “potentially a pretty serious problem” as it could not only pose a health threat, but also undermine consumer confidence.

CRE Superbug Raw Meat
There is no known case of CRE being transmitted through meat, though it is “hypothetically possible” to contract it through raw or undercooked meat. [Image by Sean Gallup/Getty Images]

Wittum then points to the obvious. The CRE superbug infection was spreading in the highest concentrations in the farrowing barns, which are also the places where the highest use of antibiotics was occurring. Wittum believes that routine dosing could have led to the CRE mutating and growing stronger there. Speculation on how the superbug was introduced focuses on people and equipment at the farm.

Dr. Gandra goes a step further and questions whether or not the antibiotics should be used in the way that they are presently being used, while also noting that it would be impossible to eliminate the use of antibiotics since they are used to treat sick animals. But Dr. Gandra also notes that the use could be more restrained, and not incorporated into growth promotion and preventative uses.

Both experts mentioned the widespread use of antibiotics in the farrowing barns as a possible explanation for the CRE spread. Neither is claiming it as a sure cause. Perhaps future investigations will fill in those blanks about the first CRE superbug outbreak on a farm in the United States.

[Featured Image by Scott Olson/Getty Images]