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FDA’s Is Just One Approach To Antibiotics

This month, the Food and Drug Administration announced a plan to address the problem of antibiotic-resistant bacteria in food and on farms. The FDA’s effort to tackle the issue began with a 1970 report titled “The Use of Antibiotics in Animal Feed” and has arrived, nearly a half-century later, at a two-pronged recommendation for controlling antibiotics that are also given to humans: eliminating their use to promote livestock growth (rather than to prevent or treat illness) and requiring prescriptions.

Will the plan work? Given that hard numbers — how much antibiotic is used on farms, how much of that is used for growth, and how much any of it contributes to resistance — are hard to come by, it’s anybody’s guess.

Although everyone agrees that antibiotic-resistant infections are a pressing problem — they kill 65 people every day — it’s clear that antibiotic use in people is the root of the most dangerous infections. The Centers for Disease Control and Prevention (CDC) says that at least half of human use is inappropriate, and the three bacteria classified as “urgent” threats are unlikely to have a farm connection. But resistant salmonella and campylobacter are listed as “serious” threats and could come from livestock, which receive more than half of the antibiotics used in this country. (Keep in mind that animals outnumber people; we slaughter more than 110 million pigs, 34 million cattle and 8 billion chickens in this country every year.)

There are undoubtedly resistant salmonella and campylobacter on farms and in people. But drawing a connection is tricky. Tom Chiller, an infectious-disease specialist whose work for the CDC included a three-year stint heading the organization’s bacteria-tracking system, says that, in the case of food-borne infections, most of the development of resistance came from antibiotics used on animals. “It’s indisputable,” he says, but adds, “it’s challenging to show the exact link from Person A to Cow A.”

The search for the smoking gun is complicated by the shape-shifting ways of bacteria. They can alter their genes. They can exchange them with other bacteria. The bacteria in Person A may have looked quite different when they were in Cow A.

Absent data on the frequency with which Cow A infects Person A, scientists are forced to speculate. The nature of that speculation depends on who’s doing it. David Warner, director of communications for the National Pork Producers Council, says that while antibiotics used on cows, pigs and chickens “could lead to antibiotic treatment failures in people, numerous peer-reviewed risk assessments, including at least one conducted by FDA, have found that antibiotics used in food-animal production pose a negligible risk of causing antibiotic treatment failures in people.”

The National Academy of Sciences has a different list of citations, of studies that conclude: “The widespread use of these powerful and persistent chemical agents in livestock ... is associated with the emergence of drug-resistant infections in these settings and has been linked to the establishment and spread of drug-resistant infections in humans.” The CDC and the FDA agree, and I have yet to find a mainstream science or public health organization that sides with the pork producers.

Stuart Levy certainly doesn’t. He’s director of the Center for Adaptation Genetics & Drug Resistance at Tufts University School of Medicine, and he has worked with the FDA and testified before Congress on this issue. Levy says the pork producers’ position “makes no sense to me.” He acknowledges the Cow-A-to-Person-A linkage problem, but adds, “If 70 percent of antibiotics are given to animals, and we agree that antibiotics select for resistance, you have to conclude that antibiotic use contributes to drug resistance.”

Levy says he isn’t convinced that the FDA guidelines will work, for the simple reason that they’re voluntary. “No one’s been eager for it to become non-voluntary,” he says. “You want people to believe in the reasons for eliminating this kind of use. But I don’t think voluntary change in this kind of use will work. I’m sorry, because that’s what I would have liked.”

Rep. Louise M. Slaughter, D-N.Y., agrees, and she has sponsored a bill her office characterizes as “a hard requirement that an animal has to be sick in order for an antibiotic to be used.” The act would be much more restrictive than the FDA guidelines : It would have the force of law and would forbid the use of antibiotics for preventing illness. Since antibiotics kill bacteria, farmers can theoretically call any use “prevention.”

I talked with several people connected with the meat industry and found lukewarm support for the FDA guidelines and dead-set opposition to Rep. Slaughter’s legislation, PAMTA. The industry’s objection to PAMTA’s restrictions is rooted in the idea that antibiotic use makes animals healthier and improves the overall safety of our food supply. “There can be greater food safety risks when antibiotics are not used,” says Christine Hoang, a veterinarian and assistant director of the Scientific Activities Division of the American Veterinary Medical Association.

In the context of the way conventional farmers now raise pigs, chickens and cows, I suspect that’s true. The larger question is whether we should be raising livestock in conditions such that their health depends on regular use of antibiotics. The only reason we were able to bring animals indoors and raise them at current densities is that we had drugs to control disease. As one study of resistance published in the Journal of Food Protection noted, “Conventional swine production evolved to routinely use antibiotics.”

As we learn more about the human immune system, it’s becoming clear that exposure to microbes can help us develop disease resistance. The hygiene hypothesis works with pigs, too. When John McGlone, an animal scientist and professor at Texas Tech University, put 8-week-old feral pigs together with their domestic counterparts, the indoor pigs all came down with brucellosis, a bacterial disease that can lead to infertility and lameness. The feral pigs brought the bacteria in, but it didn’t make them ill. “Feral pigs are tough,” he says. “They’re at one end of the spectrum of pigs. Then outdoor pigs. Then dirt lots. Then inside a dirty building, then inside progressively cleaner buildings.”

One way to protect animals from dangerous organisms is undoubtedly the clean way. The other is the dirty way. Smaller farmers, raising smaller herds outdoors, borrow a leaf from those feral pigs’ book. One example is Walter Jeffries, who raises pigs on grass in Vermont, at Sugar Mountain Farm. He’s ready to use antibiotics if one of his pigs gets sick, but that doesn’t happen very often. “They are pretty hardy animals,” he says. “What doesn’t kill them leaves them stronger. Over time this leads to a more robust and healthier herd.”

The clean way has enabled economies of scale that keep meat cheap, and a shift toward the dirty way would inevitably raise prices. From a public health perspective, though, that might not be a bad thing. “There are now pretty strong lines of evidence that Americans eat too much meat — especially red and processed meat — so a reduction would clearly lead to better health,” says Eric Rimm, associate professor of epidemiology and nutrition at the Harvard School of Public Health. How much better, of course, depends on what people eat instead. Beans would be a big win. Pasta wouldn’t be. But it’s hard to make the case that an abundant supply of cheap meat is a public health plus.

Because the extent to which the new FDA guidelines will curb antibiotic resistance is anybody’s guess, here’s mine: They will, at least a little. The farmers and vets I spoke with recognize the problem and want to be part of the solution. But I think it’s a mistake to lay all the responsibility for the fix at the feet of our farmers. Antibiotic-resistant bacteria threaten all of us, and we can all do our part simply by opening our wallets. Create demand for meat raised without, or with fewer, antibiotics. Send the message that there’s a market. That message will be passed up the food chain, and it will ease the way for farmers to make changes that benefit all of us.