Forty years later, FDA finally restricts use of antibiotics in livestock

Forty years after it first made the attempt, the U.S. government has instituted controls on some antibiotics used in meat animals to prevent the emergence of resistant bacteria that threaten human health.

The rules, known technically as Guidance for Industry #213, put an end to two longstanding practices: giving antibiotics to animals to make them gain weight, a practice called “growth promotion,” and buying antibiotics in a feed store or over the internet with no veterinary oversight. With the new rules in effect, growth promotion becomes illegal in the United States, and antibiotics that are judged “medically important” — that is, needed to cure specific human infections — become available to the livestock industry only through authorization by a veterinarian.

The rules do not ban all antibiotic use in livestock raising, and some advocates worry that they may not have as much effect as the FDA believes. But their implementation, scheduled for Jan. 1 and confirmed by the FDA Tuesday afternoon, marks an important shift in a battle that has been going on since 1977, the first time the agency tried — and failed — to restrict farm antibiotic use.

“This is a great step in the right direction,” said Karin Hoelzer, a veterinarian and senior officer in the Pew Charitable Trusts’ antibiotics project. “But more needs to be done.”

The new rules also put the United States in line with the European Union, where growth-promoting antibiotic use has been outlawed since the beginning of 2006. However, European countries discovered after their ban that routine antibiotic use continued, resistant bacteria kept emerging, and additional political action was necessary to reduce the threat.

The question of how, and for how long, drugs are used may seem like an abstruse legality, but it has real-world consequences. For instance, health authorities around the world have been worried for more than a year about the advance of a type of antibiotic resistance known as MCR, which disables a drug called colistin.

Colistin is one of the last antibiotics available to human medicine; it has only recently come into use — after years of being deemed too toxic by doctors — because so many other antibiotics have lost their power. But MCR, which gives bacteria defenses against colistin’s attack, emerged because colistin was being used in livestock, not to promote growth but as a preventive treatment. So far, MCR has been found in more than 30 countries.

It won’t be clear whether the new rules actually change farm antibiotic use in the U.S. until sometime toward the end of 2018, when federal data on antibiotic use in 2017 is slated to be published. The most recent data, released just before Christmas and covering through 2015, shows that antibiotic use in U.S. food animals has been rising steadily since the government started keeping track, and now stands at 34.3 million pounds per year, with 21.4 million pounds of that total being “medically important.” (The remainder includes drugs that either don’t provoke resistance, or for which resistance would be unimportant since they are not used in human medicine.)

That federal data, known as the ADUFA Report after its enabling legislation, the Animal Drug User Fee Act, suggest how much of an impact the new rules could have if they are followed as intended. In 2015, 97 percent of “medically important” antibiotics were sold without veterinarian consultation, and under the new rules that should end.

But the data also show how much wiggle room is allowed under the definitions of farm drug use. In 2015, for instance, 71 percent of agricultural antibiotics were used for “production or therapeutic indications,” meaning they might have been used for weight gain, but they also might have been given to protect animals from possible diseases.

Only the first of those is forbidden by the new rules. Preventive dosing is allowed. (As is therapeutic dosing — treatment of a diagnosed disease — but no one has ever suggested banning that use.)

“This is a massive loophole,” said Avinash Kar, a senior attorney at the Natural Resources Defense Council, which previously sued the FDA to force changes in its antibiotics rules. “If you have two roads that are headed to the edge of a cliff, and you only close off one road, it doesn’t stop cars from driving over the cliff.”

Preventive use is supposed to be kept in check by veterinarian oversight. But an analysis done by Pew last fall revealed that one-third of antibiotics that remain approved in the wake of the new rules are sold in ways that permit them to be misused. On their labels, which are legally binding, those drugs have growth-promoter-like indications, such as “maintenance of weight gain,” or have no dosage or no duration of use specified.

“There is still an opportunity for routine, widespread use,” said Steven Roach, the food-safety program director at the Food Animal Concerns Trust. He pointed out that tylosin, a veterinary drug that is used to prevent liver abscesses in cattle and is related to the human drug erythromycin, has no duration of use and thus can be given for the entire six months that a beef calf lives in a feedlot. (Durations may also be unrealistic. In its own documents, the FDA mentions “16 weeks” as an appropriate duration for a chicken, when most broilers live only six weeks.)

Last September, the FDA began to address the duration issue, soliciting comments on its website about whether the rules for how long to give antibiotics should be hardened. The comment period was scheduled to end in December, but was extended to March; there have been 188 comments so far, and the idea of tightening duration rules is unpopular with animal-production organizations.

Experts concerned that the new rules don’t go far enough point out, with some impatience, that there already are models to follow for further restricting antibiotics while protecting animal health and farm productivity. “We know this can be done, because we have seen entire countries — both the Netherlands and Denmark — take preventive use off the table and show they can succeed,” Kar said.

Maryn McKenna is a National Geographic contributor, and the author of Superbug and Beating Back the Devil. She last wrote for FERN about how the Netherlands cut antibiotic use on farms. Her new book on antibiotics in agriculture will be published later this year by National Geographic Books/Penguin Random HouseShe writes regularly about antibiotics and agriculture for Ag Insider.