Is the FDA about to ban antibiotics for cows? Maryn McKenna explains …


There's been a flurry of headlines the past couple days about new FDA rules for antibiotic use in animals meant for the table. To get a better understanding of what's going on and what it means, I turned to my favorite Scary Disease Girl, Maryn McKenna, author of Superbug, a book about the antibiotic-resistant bacteria that evolve when we use too many antibiotics, too often, on both people and animals. Here's what she had to say:

Short version: Yes, the FDA is considering doing something; the guidelines the NYT talked about were actually published in June. No, they're not banning antibiotic use; what they're talking about is voluntary guidelines, not legislation or regulations. Yes, there is abundant science to support making this move; it's been clear for decades that antibiotic overuse in farming fosters the growth of drug-resistant organisms that affect humans. No, the agricultural industry does not agree.

And now, the long version …

Antibiotic use in farming breaks down into three major categories. There's therapeutic use, giving antibiotics to sick animals to treat disease. (No one that I know of argues with that.)

There's prophylactic use, giving antibiotics to healthy animals to prevent them developing diseases.

And there's growth promotion: That's giving small doses of antibiotics to animals because it helps the animal put on weight faster, which if you're growing animals for the purposes of getting them to market weight and selling them, looks like an efficient goal.

Growth promotion—sometimes called subtherapeutic dosing or "for production purposes" in the FDA's very careful languag—has been around since the 1940s, when a couple of scientists at Lederle Labs wanted to find a use for the carbohydrate mash left over from manufacturing chlortetracycline, and decided to try it out as a chicken feed. It's been fully banned in the European Union for four years on evidence that those small doses contribute to the development of resistant bacteria in animals and the farm environment.

One of the chief drivers of the EU ban was a link between the use of a drug called avoparcin on farms, and the occurrence of the virulent hospital organism vancomycin-resistant Enterococci (VRE) in humans; avoparcin and the last-resort human drug vancomycin are very similar. When avoparcin was removed from use, VRE rates declined.

The FDA has been looking at growth promoting antibiotics since the 1970s, but it has never banned them, and it isn't proposing to do so now. What it wants, instead, is for agriculture to agree to two things: Voluntarily stop using using subtherapeutic growth-promoting dosing, and involve veterinarians in the administration of antibiotics to farm animals.

There's legislation in Congress, the Preservation of Antibiotics for Medical Treatment Act, that would go much further, but the FDA is treading carefully and starting small. They may have tougher action in mind, though: Deputy FDA Commissiner Dr. Joshua Sharfstein said in testimony in June: "We have the regulatory mechanisms and the industry knows that. But we are also interested in what things can be done just voluntarily that they would do them. And I think it'll be interesting to see how the industry responds to this."

Maryn McKenna is a journalist and author and blogs about scary diseases and food policy at Superbug.

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