New Antibiotic-Resistant Gene Found in Pigs: Another Reason to Go Organic?

Could a bite of a fatty, tasty pork chop or juicy carnitas alter the body’s resistance to critical life-saving antibiotics? According to new research out of China, yes.

Authors of a recent study in the journal Lancet Infectious Diseases were looking for antibiotic resistance in the E. coli that reside in the guts of food animals. Within that E. coli, they found a gene—which they’ve dubbed MCR-1—that is resistant to a group of antibiotics called polymyxins, including an old, rarely used drug called colistin.

Colistin has been shelved for decades since it was first introduced in 1959, due to its toxicity to the kidneys. However, it is sometimes used as a last resort for life-threatening infections. Now, colistin may end up being ineffective in the most dire circumstances if this resistant bacteria spreads—and it seems poised to do just that.

Colistin is actually present in some livestock since it’s used as an additive to animal feed to make them gain muscle mass faster and protect them from the diseases that spread through factory farms.

After discovering the colistin-resistant E. coli in a pig from a factory farm near Shanghai, the scientists conducting the Lancet Infectious Diseases study decided to test more slaughtered animals, meat sold in markets, and samples from hundreds of patients with bacterial infections. Between 2011 and 2014, they found MCR-1 present in 15 percent of 523 samples of raw pork and chicken, 21 percent of 804 samples of slaughtered pigs, and 1 percent of 1,322 samples from hospital patients.

We already know resistance genes can spread—they’re contained on plasmid, cellular DNA molecules that move freely from one bacterium to another. MCR-1 is no different. These findings suggest it’s already started to spread around Shanghai, and the study authors predict it will be able to proliferate from there.

While China is the world’s largest user of colistin in agriculture, the global demand for the drug is expected to hit 11,942 metric tons annually by the end of the year and rise to 16,500 metric tons by 2021. The more animals consume colistin, the more strength MCR-1 will gain against it. And with ten percent of China’s meat produced specifically for export, the odds of this antibiotic-resistant gene spreading through meat consumption are a very real global concern.

A representative from the World Health Organization told the Pharmaceutical Journal that the only viable solution right now is to limit or eliminate agricultural use of antibiotics in food. Until that happens, consumers who haven’t yet found a strong enough reason to go organic, this might be it.

Photo credit: Gillian Van Niekerk via Stocksy