Livestock antibiotics and superbugs

From Tom Laskawy, on

Smoking gun image via

“How does the livestock industry talk about antibiotics? Well, it depends on who’s doing the talking, but they all say some version of the same thing. Take the National Cattlemen’s Beef Association; they say there is “no conclusive scientific evidence indicating the judicious use of antibiotics in cattle herds leads to antimicrobial resistance in humans [MRSA].”

Or Ron Phillips of the Animal Health Institute (a drug-industry front group). In an interview on Grist last year, he said that before you can draw any conclusions:

“…You have to look at specific bug/drug combinations and figure out what are the potential pathways for antibiotic-resistant material to transfer from animals to humans. Studies have been done, and have come to the conclusion that there is a vanishingly small level of risk.”

The message is clear. Until scientists trace a particular bug from animals to humans and show precisely how it achieved resistance and moved from farm to consumer, there’s no smoking gun. Thus industry leader’s heads can remain firmly buried in the sand.

Ladies and Gentlmen, we now have a smoking gun! NPR reported on it first; here’s their take:

study in the journal mBio, published by the American Society for Microbiology, shows how an antibiotic-susceptible staph germ passed from humans into pigs, where it became resistant to the antibiotics tetracycline and methicillin. And then the antibiotic-resistant staph learned to jump back into humans.

“It’s like watching the birth of a superbug,” says Lance Price of the Translational Genomics Research Institute, or TGen, in Flagstaff, Ariz.

The superbug at issue is a strain known as “Pig MRSA.” It’s the bug I discussed with WIRED writer and Scientific American editor Maryn McKenna recently, and the same one scientists found on retail meat in another study.

The mBio study authors found that ST398 started as a not-quite-resistant strain of staph in humans, jumped to pigs, where it acquired resistance to antibiotics, jumped back to the humans who lived near the pigs, caused disease, and then, like many rural residents before it, left the farm to find its fortune in the big city.

Maryn McKenna on her Superbug blog on WIRED warns those who might consider all this “no big deal” and sums up the significance of the new study’s findings:…”

Read it all on


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