Giving routine antibiotics to livestock has been sharply curtailed in the United States, thanks to new rules by the Food and Drug Administration that went into effect on January 1.
The change has been long awaited; the FDA first attempted to control farm antibiotic use in 1977. The new rules are aimed at controlling antibiotic-resistant bacteria moving off farms as a result of antibiotic use, and they bring the U.S. in line with rules that have existed in the European Union since 2006.
The FDA’s new rules are complex and don’t ban all antibiotic use — and because of that, some advocates are worried they will not be as effective as hoped. But the rules nevertheless represent an important inflection point in what has been a decades-long fight over antibiotic use in livestock, and they may herald further restrictions to come.
“I think this is big,” said Ramanan Laxminarayan, who is director of the Center for Disease Dynamics, Economics and Policy in Washington, DC and sits on a national council advising the White House on antibiotic policy. “It sends a strong signal to the (agricultural) industry that the FDA is willing to get into the picture to protect the effectiveness of antibiotics, and that is an important move.”
As with any government move, the history is complex. At the beginning of the antibiotic era, researchers discovered that the new miracle drugs had an unanticipated second effect: When given in tiny doses to healthy livestock — poultry, cattle, hogs — they allowed the animals to gain weight faster than they would have otherwise. When given to entire herds or flocks in slightly larger doses — but still smaller than it would take to cure an infection — antibiotics protected animals from illness.
Those two practices — growth promotion and disease prevention— effectively created modern industrial farming by allowing animals to be raised intensively and rapidly in limited space.
They also became the basis of an enormous industry. In 2015, the most recent year for which the FDA has collected data, veterinary pharmaceutical manufacturers in the United States sold 34.3 million pounds of antibiotics for use in animals. (According to the Pew Charitable Trusts, which retrieved numbers collected a few years earlier, humans in the United States use 7.7 million pounds.) But from the 1960s, those practices were shown to lead to increases in drug-resistant infections, adding to antibiotic resistance that was already arising from misuse in medicine.
Nothing like growth promotion or disease prevention exists in human use of antibiotics; medicine limits the drugs to treatment of diagnosed infections. In 1977, then-FDA Commissioner Donald S. Kennedy attempted to ban growth-promoter antibiotics in the United States, arguing that they created resistant bacteria without conferring any benefit in the way that human use of antibiotics does. His attempt was shut down by Congress, and the issue remained off the table until it was revived by the FDA in 2013.
The FDA’s new “judicious use” rules make growth promotion illegal in the United States, and put antibiotics used for prevention under the control of veterinarians. (Previously, farmers could buy many antibiotics at feed stores or over the Internet.) But they do not ban all antibiotic use, and groups that have been following the issue for years worry they contain too many loopholes.
“These guidances are half-measures for a problem that requires a full-scale solution,” said Matthew Wellington, field director of the antibiotics program at the nonprofit US PIRG. “We need to not just phase out growth promotion, but eliminate the entire routine use of antibiotics in otherwise healthy animals. Antibiotics are miracles of modern medicine, and we cannot squander them in this way.”
Advocates are especially concerned because of what happened in Europe. After the European ban on growth promoters, several countries found that antibiotic use within their borders did not change; the same drugs were merely relabeled as preventive. Farm antibiotic use did not diminish in the Netherlands, for instance, until that country’s government worked out a collaboration with organizations representing farmers. Within two years, the Netherlands reduced all farm antibiotic use by half.
Preventive antibiotic use on farms is an especially important concern right now, because the latest highly resistant superbug moving across the world emerged because of farm use of preventive antibiotics. That resistance factor, known as MCR, undermines the effectiveness of an antibiotic called colistin, which medicine has recently begun using because so many other antibiotics have lost their power.
Medicine kept colistin on the shelf for decades because it has toxic side effects and other safer drugs were available. But in the years that medicine did not use it, agriculture did; livestock in Europe and China receive millions of pounds of the drug. MCR has now been found in more than 30 countries, including the United States.
How much preventive use of antibiotics will occur in the U.S. after the FDA ban is hard to predict. One-third of the drugs listed for preventive use are sold with no limits on how long they can be used, meaning they could be given throughout an animal’s life, defeating the new rules. The FDA is currently collecting public comment on whether restrictions should be tightened.
“Preventive use needs limits,” said Avinash Kar, a senior attorney at the Natural Resources Defense Council, which previously sued the FDA to force changes in its antibiotics rules. “There may be limited instances where prevention might be appropriate, but they need to identify what those are, and not allow routine broad-scale use.”
The success of the new FDA rules won’t be clear for almost two years, because the FDA won’t compile and publish 2017 data until the end of 2018. In the meantime, the best indicator of whether the new rules work may be whether a new superbug emerges that can be linked to farm antibiotic use, or whether we are spared.