Every day, Americans use some 51 tons of antibiotics.
But only about a fifth of that is to treat human illness. Most of the rest is given to livestock — and not because the animals are sick. Instead — despite increasing antibiotic resistance among pathogens — the drugs are used for what the FDA calls “production purposes”: to help animals gain weight more rapidly or to improve feed efficiency.
Those uses, the agency said in a guidance issued in December, are no longer “judicious” and should be stopped.
Last year, the FDA asked farmers voluntarily to agree only to use antibiotics to promote animal health and only then if the use is approved by a veterinarian.
In the December guidance, the agency asked drug-makers to take production uses off antibiotic labels within 3 years.
The reason is clear, according to Richard Whitley, MD, of the University of Alabama Birmingham: “We know that exposure of animals to antibiotics can promote the development of antibiotic resistance.”
“It's not the only mechanism of antibiotic resistance,” he told MedPage Today, “but it's a big one that we need to worry about.”
The agency's guidance is a “tremendous, tremendous ruling,” he said.
Others were not so sure. In an online column, economist Charles Kenny, MA, of the Washington-based Center for Global Development, called it “inadequate” because of its voluntary nature.
The guidance “politely requests in an absolutely nonbinding manner that pharmaceutical companies change their drug labeling to suggest antibiotics shouldn't be used to promote growth in farm animals,” Kenny wrote.
The agency said it will revisit the issue in 3 years and perhaps take additional action then if the voluntary process has been unsuccessful.
That's not the right approach, Kenny argued, urging the FDA to work with other governments and international agencies to develop a “binding global agreement on the use of antibiotics — one that will cover research, prescription regimes, and use in agriculture.”
If the FDA's approach works, Whitley argued, “over the next 3 years you'll see antibiotics be eliminated from animal feed.”
That should mean a decrease in the development of resistant microorganisms, he said, and a slight increase in food prices.
But, he noted, the U.S. is lagging on the issue. “The European countries are far ahead of us,” he said. “They've already banned antibiotics in animal feed, so we're just playing catch-up.”
Whether an outright ban is the right approach is itself an open question, argued Aidan Hollis, PhD, of the University of Calgary, and Ziana Ahmed, BASc, of the University of Toronto, both in Canada.
In a perspective article in the New England Journal of Medicine, they argue that banning production uses might be difficult.
For one thing, such a ban would have to be enforced, so that some farmers couldn't cheat and gain a competitive advantage.
Requiring vets to provide oversight would also be a problem for “geographically remote” farms and fish farms, and in any case would mean more vets would be needed.
And it's not entirely clear where the line between production use and therapeutic use should be drawn, they argued, noting that in some circumstances prophylactic antibiotics — a production use — would reduce the need for therapeutic drugs.
On the consumer side, they said, estimates suggest that banning antibiotics as animal-growth promoters would increase farm production costs by between $1.2 billion and $2.5 billion a year in the U.S.
The increase “pales in comparison” with the value of antibiotics for human therapy, they wrote, but it would be passed on to consumers and would mainly affect the poor.
A more rational approach, they argued, would be to impose a user fee on nonhuman use of antibiotics — an approach that would have several advantages over an outright ban:
- It would be easy to administer, since a fee could be imposed at the point of sale or during manufacturing.
- It would deter “low-value uses” of antibiotics and would reward farming operations that had good substitutes, such as vaccinations or better animal management.
- It would generate revenue that could be used to “help to restock and maintain the antibiotic cupboard, which is looking increasingly bare.”
- And it would be easy to replicate internationally.
The authors suggest that an international treaty imposing such fees would level the playing field for agricultural producers and the revenue involved would be attractive to governments.
“By contrast, a ban, which disadvantages local producers while providing no revenues to government, would be much less attractive to enforce,” they concluded.
Regardless of that debate, evidence is mounting that nonhuman use of antibiotics is a risk factor for human health. In November, researchers in Pennsylvania found that proximity to high-density swine production operations was associated with greater risk of acquiring methicillin-resistant Staphylococcus aureus (MRSA).
And in 2012, other researchers made a similar finding, this time looking at farms in the Netherlands.