Another scary superbug has been found on an American hog farm

Researchers went looking for one type of antibiotic-resistant bacteria, only to find one that had no reason to be there.


If you weren’t already alarmed by the rise of antibiotic-resistant bacteria, consider this: Scientists recently went looking for one type of superbug lurking among livestock only to find another superbug they weren’t expecting.

You can add Dr. Thomas Wittum to the growing list of researchers who’ve earned the dubious distinction of being the first to discover some particular strain of dangerous antibiotic-resistant superbug on an American factory farm. In this case, Wittum and his team from Ohio State University—where Wittum is chair of the department of veterinary preventive medicine—found what is known as carbapenem-resistant enterobacteriaceae on a pork farm in the Midwest. CREs have been classified as an urgent threat by the Centers for Disease Control and Prevention, owing to these superbugs having “become resistant to all or nearly all the antibiotics we have today”—including the class of antibiotics called carbapenems, one of the last remaining groups of antibiotics that are still effective in treating potentially fatal multi-drug-resistant infections in people.

“We weren’t expecting this, and we were quite surprised,” Wittum told Maryn McKenna at Fern’s AG Insider. “We had predicted that the common CREs in U.S. health care would be the ones we would first start to see in animals, but this is a really unusual one”—not least because carbapenems aren’t even used in livestock. Wittum and his team had gone searching for bacteria that are resistant to another class of antibiotic, cephalosporins, which are commonly used in pigs.

Meaning what? Well, somehow potentially disease-causing bacteria resistant to an antibiotic of last resort for humans ended up on a pig farm where the animals never received that antibiotic. More research is necessary to determine how it might have happened, but it suggests a worrisome new wrinkle in the spread of antibiotic-resistant superbugs: People (e.g., farmworkers) could be transporting strains of bacteria to factory farms. There, the bacteria can grow into superbugs, as the strains are exposed to a plethora of antibiotics, which they develop an ever stronger resistance against.

Indeed, despite years of increasingly dire warnings from medical experts and public health advocates, some 70 to 80 percent of all antibiotics used in the United States aren’t used to treat sick people or even sick animals. Rather, they are given to otherwise healthy livestock to promote growth and prevent illness—the sort of illness that’s inevitable on your average overcrowded factory farm. The Food and Drug Administration has been ridiculously slow to address the problem and, to date, hasn’t taken any serious action that would stem the tide of antibiotic abuse on factory farms. On the international front, more than 190 nations signed on to a United Nations declaration in September promising to take action to address the mounting crisis of antibiotic resistance. But the declaration is nonbinding and doesn’t set any firm targets for reining in the overuse of these lifesaving drugs that are rapidly losing their potential to, well, save lives.

As David Wallinga, a physician and senior health officer at the Natural Resources Defense Council, put it to Fern’s Ag Insider, “The pattern we see with enormous antibiotic use in livestock, including pigs, is: ‘Oh, that’s not a problem.’ And then the next stage is, ‘Well, it’s a hypothetical that’s a problem.’ And then, ‘Well, it might be a problem in the United States, but people aren’t dying yet.’ And the last stage is, ‘Well, not very many people are dying.’ As a public-health person, I don’t want to see us get to that last stage.”


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