September 01, 2009


 FDA backs legislation to restrict antimicrobial use

Deputy commissioner says growth-promoting use should be phased out

By Greg Cima
Posted Aug. 15, 2009

The Food and Drug Administration supports banning the use of antimicrobials to promote growth or feed efficiency, a deputy commissioner said.


Joshua M. Sharfstein, MD, principal deputy commissioner for the FDA, testified July 13 before the House Committee on Rules that use of antimicrobials should be limited to the protection of human and animal health, and the FDA supports proposed legislation that would phase out use of antimicrobials for growth promotion or feed efficiency in animals. He said eliminating those uses would not compromise food safety.

Dr. Sharfstein was one of eight witnesses scheduled to testify before the committee that day in a hearing on the Preservation of Antibiotics for Medical Treatment Act of 2009, information from the committee states. The AVMA is opposed to the bill.

The bill was introduced in March with the stated purpose of preserving the effectiveness of antimicrobials for use in treating disease by phasing out what the bill calls nontherapeutic uses in food-producing animals. But the AVMA opposes the measure, saying that it would increase animal disease and death and decrease animal welfare without reasonable assurance of a benefit for human health.

Such uses prevent and control subclinical disease in animals, and reasonable alternative interventions do not exist, the AVMA has said. Additionally, PAMTA would ban the use in animals of drugs that are not important to human medicine.

The AVMA supports risk mitigation actions to protect human health when they are based on scientific evidence that they will be effective. For example, the AVMA participated in the creation of the 2001 Public Health Action Plan to Combat Antimicrobial Resistance and has since supported the plan, which was outlined by Dr. Sharfstein in his testimony. The AVMA has also created judicious therapeutic antimicrobial use guidelines for veterinarians.

In prepared comments submitted to the House Committee on Rules, Dr. Sharfstein testified about FDA opposition to antimicrobial use for growth promotion and feed efficiency, but he said the legislation should allow judicious use of antimicrobials for the prevention and control of disease. As the bill is currently written, PAMTA would make some preventive uses illegal.

His written testimony also states that prior to preventive use of antimicrobials, a determination should be made that the use would be effective, consistent with accepted veterinary practice, linked to a specific causative agent, and appropriately targeted and that no reasonable intervention alternatives exist.

"FDA also believes that the use of medications for prevention and control should be under the supervision of a veterinarian," he said.  

Veterinary perspectives

Dr. Lyle P. Vogel, assistant executive vice president of the AVMA, expressed surprise that the FDA prefers a legislative solution instead of the normal FDA science-based process mentioned in Dr. Sharfstein's testimony and the process in the Public Health Action Plan to Combat Antimicrobial Resistance. If the FDA thinks there is an imminent public health risk, the agency has the authority to withdraw drug approvals prior to conducting hearings. 


"I think sometimes we attempt to avoid issues by trying to eliminate every possible risk factor without scientific knowledge or data to support those assumptions, and I think that's what's happening here. In an effort to find a solution to the antimicrobial resistance problem, the FDA has gone after, I guess, the low-hanging fruit."


In talking about FDA support for PAMTA, Dr. Sharfstein said the statutory process used by the FDA to withdraw new animal drug approvals is burdensome on his agency. An FDA spokeswoman contacted later said the agency declined to elaborate on that comment.

Dr. Rodney "Butch" Baker, president of the American Association of Swine Veterinarians, does not see the pending legislation as a prudent or reasonable defense against development of antimicrobial resistance. Swine veterinarians are judicious in administering antimicrobials, he said, and they do not substantially influence antimicrobial resistance in human medicine.

"I think sometimes we attempt to avoid issues by trying to eliminate every possible risk factor without scientific knowledge or data to support those assumptions, and I think that's what's happening here," Dr. Baker said. "In an effort to find a solution to the antimicrobial resistance problem, the FDA has gone after, I guess, the low-hanging fruit."

Dr. Baker supports increasing veterinary control over antimicrobial use, but with flexibility in combating infectious disease. Risk assessments, molecular epidemiologic studies, and surveillance indicate use in livestock is not the source of resistance in humans, and the current legislation is a political move intended to show people the government is taking judicious action, he said.

Antimicrobials used to prevent disease lead to increased growth rates and feed efficiency, which are the result of controlling pathogens, Dr. Baker said. The phrase "growth promotion" has become outdated, he said, and anti-meat activists have used the term as a catch phrase for inappropriate use.

Dr. Baker said antimicrobial concentrations considered to be growth-promoting lower morbidity and mortality rates in animals, particularly among those in nurseries. He said restrictions on antimicrobials that have worked in the past could have unintended negative consequences for food safety and animal health without addressing problems of resistance in human medicine.

"If we do have a loss of antimicrobial use, will that lead to poorer health?" Dr. Baker said. "And with poorer health in animals that we're raising for food, will that actually increase risk to the consumer?"  


The pending legislation has been supported by physician, nonprofit, food service, and activist organizations critical of animal agriculture's use of antimicrobials. Other witnesses who provided testimony to the rules committee in favor of PAMTA included officials with the Union of Concerned Scientists, the Translational Genomics Research Institute, the Pew Environmental Group, Chipotle Mexican Grill, and Bon Appétit Management Company. 

Margaret Mellon, PhD, director of the Food and Environment Program for the Union of Concerned Scientists, said in written testimony given to the committee that the FDA has failed to adequately use its authority to withdraw antimicrobials no longer safe for use in food-producing animals.

"This legislation would require the FDA to review antibiotics used in animal agriculture to determine whether they put public health at risk by leading to increased resistance, and to withdraw from the market in a timely manner those drugs that cannot be shown to be safe," she said.

But Dr. Vogel explained that PAMTA would not require the FDA to review antimicrobials. The legislation instead presumes all routine use in animals of antimicrobials that are used in humans creates a public health risk, and that these antimicrobials should be withdrawn from the market unless someone proves otherwise.