When the U.S. Food and Drug Administration (FDA) released draft guidelines for the judicious use of antimicrobials in food animals last June, the agency welcomed a flood of input from individuals and organizations during a 60-day commenting period.
Still under review several months later, the 531 comments submitted to the FDA underscore a debate that weighs the food safety and economic benefits of antibiotics against the wider medical threats stemming from their extensive use.
Fully titled “The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals,” the FDA’s draft guidance sets forth recommendations for food producers to discontinue using medically important antimicrobials on healthy animals for growth promotion purposes, instead reserving them for disease treatment and prevention. It also recommended food producers use such drugs only under veterinary consultation.
The phrase “medically important” describes antibiotics and other drugs that are useful in human medicine. Though some antibiotics are used only in livestock, the majority are classified for both humans and food animals.
According to FDA spokeswoman Laura Alvey, the agency does not have a timeframe for releasing the final version of the guidelines, though the process of reviewing the public comments and implementing a final set of guidelines is a priority. FDA principal deputy commissioner Joshua Sharfstein has been quoted saying the agency intends for the food industry to voluntarily adopt these practices to save the FDA from formulating regulation on the issue. Unlike regulations, guidelines are not legally enforced, but are instead provided as recommendations.
As the draft guidance explains, medical experts have long-recognized that overuse of antimicrobial drugs directly contributes to a rising development of drug-resistant bacteria. This poses a public health risk, as infections from resistant bacteria become more common when the drugs are used to greater extents.
The Centers for Disease Control and Prevention (CDC) considers antibiotics the most important tool for controlling bacterial diseases, but warns that many antibiotics are losing their effectiveness due to their extensive use in both humans and animals. In recent decades, the CDC has tracked numerous strains of drug-resistant bacteria infecting humans–particularly MRSA–which cannot be treated with penicillins or cepholosporins. Studies cited by the CDC have correlated the use of cepholosporins on food animals with higher rates of drug-resistant Salmonella infections in humans.
Another study cited by the CDC found that drug-resistant strains of Campylobacter–one of the leading causes of foodborne disease–were infecting humans at a 20 percent greater frequency after the FDA approved a specific antibiotic class that treats Campylobacter, fluoroquinolones, for use in poultry. The FDA has since withdrawn its approval of fluoroquinolones in poultry.
According to FDA estimates, approximately 80 percent of all antibiotics sold in the U.S. in 2009 went to food animals, whether for disease treatment, disease prevention, or growth promotion. This month, an investigation by CBC TV sampled bacteria in 100 chickens from Canadian grocery stores and found that each chicken harbored bacteria resistant to at least one antibiotic, with some resistant to as many as eight.
While most professionals agree that antibiotics must be used more judiciously, the debate falls on defining the line between “judicious” and “excessive” use. The FDA guidance classifies only growth promotion as an unnecessary use, but some organizations, such as the Keep Antibiotics Working coalition, consider preventative uses to also be unnecessary under most circumstances.
One problem, however, is that antibiotics are rarely used for a single purpose in livestock. It is not uncommon for a drug to carry an all-encompassing label for disease treatment, prevention, and growth promotion, said Dr. Christine Hoang, assistant director of scientific activities for the American Veterinary Medical Association (AVMA).
For example, Hoang said, a single drug could be used in pigs for treatment at one dose, prevention at another dose, and growth promotion at another, lower dose. Antibiotics for prevention and growth promotion are typically administered to entire herds and flocks through their feed.
The AVMA does not support reductions in preventative antibiotic use. In the association’s comment on the guidelines, it endorsed a move toward more judicious applications of antibiotics, but cautioned that not all growth promotion doses should be seen as misuses either. The comment also endorsed the call for establishing a system of veterinary oversight in antibiotic use.
“The AVMA believes that veterinarians with their unique training, knowledge, and expertise, are the only animal caretakers who have the ability to decide when antimicrobial use is appropriate and judicious,” the comment read.
The Keep Antibiotics Working coalition (KAW), a group supported by a number of medical and environmental associations–including the Union of Concerned Scientists and the Institute for Agriculture and Trade Policy–responded to the guidelines with an eight-page comment arguing that the recommendations will not significantly reduce antibiotic use in food animals, even if all food producers adopt them. Instead, KAW argued that the guidelines would likely encourage changes to drug labels, but not many changes to the way the drugs are used.
“The guidelines don’t go far enough, particularly because there’s a lot of overlap between routine preventative uses and growth promotion,” said Steve Roach, spokesman for the coalition. “They’re looking to the industry to save antibiotics for prevention, but what’s likely to happen under this voluntary approach is that the industry will change the growth promotion labels, and in situations where the same drug is used for both, it will still be used the same way.”
KAW’s comment also endorsed a move toward greater veterinary oversight, but stated that veterinarians should not be the only safeguard against unnecessary antimicrobial use. The coalition believes the guidelines underestimate the public health threat posed by using medically important antibiotics on a herd-wide scale for preventative purposes, saying drugs for prevention should be reserved for when a member of the herd is diagnosed with an illness.
Following the end of the guidelines’ commenting period in September 2010, the AVMA established a steering committee to assist the FDA with implementing a system of veterinary oversight in antibiotic applications. The association believes scientific risk assessments should determine where drug uses can be eliminated. Hoang said the battle is against antimicrobial resistance, not the antimicrobials themselves.
Speaking for KAW, Roach commended the poultry industry for its “drastic” reductions in antibiotic use over the past 20 years. He said he still saw large opportunities for voluntary reductions in the food animal industry as a whole, with market forces related to “organic” and “antibiotic free” labels potentially inspiring further reductions. Some farming practices, such as feeding grain to cattle, make antibiotics a necessary part of beef production, as the drugs prevent liver abscess problems.
“There will definitely be challenges to reducing antibiotic use,” Roach said. “We have a need for changes to management that are more in tune with animal health.”