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Drug-Resistant Bacteria in Food Persists, Despite Safeguards

Nearly a quarter of chickens tested from U.K. supermarkets are infected with bacteria that is resistant to drugs important to human health.

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Infected meat may indicate more needs to be done to prevent antibiotic use in food animals.


The Soil Association, a British nonprofit, has shaken up the contentious debate over antibiotic use in agriculture, revealing that substantial amounts of antibiotic-resistant bacteria are found on meat bought in U.K. supermarkets. This comes at a time when the United Nations is about to begins its first-ever discussion of how these drugs are used on the farm.

It’s an important piece of research, and not just for the bugs it found. The United Kingdom has had long-standing controls on antibiotic use in agriculture, ones that the United States is just now instituting. This data suggests that these controls may not be good enough. Plus, the research lands at a moment when the issue is getting national attention in the United States, thanks to a brand-new FDA initiative exploring how farm antibiotics should be administered.

The details: The Soil Association, which advocates for sustainable farming and certifies that farms and businesses are following organic standards, revealed September 5 that 24 percent of chickens it sampled carried E. coli that is resistant to cephalosporins, a class of drugs the World Health Organization says are "critically important" and should be reserved for human use.

To conduct the research, the Soil Association bought 189 packages of pork and poultry at the seven largest supermarket chains in the United Kingdom, and had them analyzed in the lab of Mark Holmes, a Cambridge University veterinarian and microbiologist.

The research also uncovered that E. coli on 51 percent of both pork and poultry were resistant to trimethoprim, part of the common combo drug Bactrim; and E. coli on 19 percent were resistant to the antibiotic gentamicin.

Trimethoprim and gentamicin are two of the most important drugs for urinary-tract infections, which are becoming increasingly antibiotic-resistant, a slow-brewing epidemic that can cause serious, even fatal bloodstream infections if not treated properly.

Emma Rose of the Alliance to Save our Antibiotics, a campaign founded by the Soil Association, says the results are a call to action: “Supermarkets must now publicly commit to policies which prohibit the routine mass medication of groups of healthy animals.”

That phrase “routine medication” is an important point. Beginning in the 1950s, food animals routinely got small doses of antibiotics in their feed or water, both because antibiotics help them put on weight faster, and also because the drugs protect them against the crowded conditions of intensive livestock production. One of those uses—the weight-gain dosing called “growth promotion”—was banned in the United Kingdom in 1969 and throughout Europe in 2005. But the preventive dosing remained legal.

Supermarkets must now publicly commit to policies which prohibit the routine mass medication of groups of healthy animals.
Emma Rose Alliance to Save Our Antibiotics

Both growth promotion and preventive dosing are legal in the United States, though the U.S. Food and Drug Administration is in the midst of a policy change that should make growth promoters unavailable after the end of this year. Just as in Europe, though, preventive dosing will remain available—even though the experience of some European countries, as well as these new British numbers, shows that preventive dosing still allows resistance to get into the food supply.

But how much and how often is hard to verify, because so little testing is conducted for resistant bacteria. “We don’t have a lot to compare this with,” Holmes tells me. “Most food-hygiene regulations look at bacteria found on meat in terms of potential illness; if more than a certain number are found, then action has to be taken. There are not many studies that systematically survey the number of antibiotic resistant bugs.”

In the United States, three federal agencies share responsibility for a project, called the National Antimicrobial Resistance Monitoring System (NARMS) that examines the occurrence of resistant bacteria in patients, in animals before they are slaughtered, and on retail meat. According to the FDA, the retail meat portion of the program samples only a few hundred packages of meat per year, subdivided among chicken, beef, pork and turkey. More detailed studies have been done by academic researchers or nonprofits, such as a major investigation of bacterial contamination of chicken by Consumer Reports in 2014.

Even without adequate data to make comparisons, “My feeling is, to find that one in every four samples of meat contain a bacteria that is resistant to (cephalosporins) is remarkably high; literally it is worth remarking on,” Holmes says. “What I am most concerned about is, we have just done this once, because that is what the Soil Association asked us to do. Is this a figure that is going up, staying the same or going down? This is the sort of testing that should be done routinely by the FDA, or the Food Standards Agency here in the U.K.”

How antibiotics can or should be restricted in food-animal production is an especially live issue in the United States right now, and not just because of the high-level United Nations meeting that takes place in New York next week. The FDA has been engaged in an attempt to control the use of growth-promoting doses in U.S. livestock production—a reboot of an unsuccessful effort it made back in 1977 to take away the licenses it had granted for farm antibiotic use.

Earlier this week, it unveiled the next step in its new “judicious use” effort: It opened public comment on a proposal to set limits on how long antibiotics can be used in animals for prevention and control of diseases, something that was previously up to veterinarians and farmers themselves.

“They are asking for technical data from producers and veterinarians—how often do these uses occur, how do you determine how long to use them for—and also for procedural information, how they should go about addressing this,” says Karin Hoelzer, a veterinarian who works on antibiotics policy at the Pew Charitable Trusts.

In the request, the FDA identifies an array of mostly older, generic drugs that can be used to prevent or treat diseases of chickens, cattle, swine, turkeys and sheep for which there is no indication on the label of how long they are to be used, or when a farmer or veterinarian should stop giving them. That opens the door to the drugs being used for long durations or forever. That both cheats around the prohibition on growth promoters, and also increases the risk of stimulating antibiotic resistance, because the longer a drug is used, the more likely bacteria are to develop defenses against it.

Pew has already identified loopholes in the new FDA regulations, drugs that appeared to be used as growth promoters but that will be allowed to remain in the market after those uses are banned. “It is good FDA is taking action on this,” Hoelzer says. “But more needs to be done.”

The U.K.'s Food Standards Agency has also vowed to take action.