WASHINGTON, DC—Federal officials testified at a House hearing in July that there is evidence of a link between antimicrobial use in food-producing animals and drug resistance in humans, and that they are taking steps to address the nonjudicious use of antimicrobials in animals.

Some health officials have been concerned about the development of human resistance when drugs important to humans are used in food-producing animals for reasons other than disease treatment, such as for production or to promote growth.

In late June of this year, FDA released a draft guidance that recommends measures to limit the use of these particular antimicrobial drugs in food-producing animals to uses that are considered necessary for assuring animal health. In addition, FDA recommends that their use in animals should include veterinary oversight or consultation. The draft guidance was open for public comment until Aug 30.

Antibiotic Use in Animals

Rear Adm Ali S Khan, MD, assistant surgeon general and acting deputy director for CDC’s National Center for Emerging and Zoonotic Infectious Diseases, told the House Energy and Commerce Subcommittee on Health that CDC supports FDA’s stance regarding the use of antimicrobial drugs. “There is unequivocal and compelling evidence that the use of antibiotics in animals leads to the development of drug resistant bacteria that has adverse impacts on human public health.”

His written testimony cited examples that he said demonstrated the movement of resistant pathogens through the food supply. One example is the emergence of multi-drug resistant Salmonella Newport, which has caused outbreaks where the source was ground beef. His testimony stated that ground beef samples have been found with the same “molecular fingerprint” as the human strain.

Khan said that studies have been conducted in the UK, Denmark, and Canada showing the relationship between antibiotic use in animals and resistance in humans. “CDC supports these efforts to minimize nonjudicious use of antibiotics in both animals and humans for better human health, animal health, and environmental stewardship.”

Whether evidence does support a link between antibiotic use in animals and antibiotic resistance in humans was debated at the hearing. “Rather than focus on theory, we must really rely on the science behind the issue. So far, there is nothing that links use in animals to a build up in human resistance,” Rep John Shimkus, R-IL.

Shimkus argued with the evidence that FDA and CDC provided to support their position, stating that “equating animals to people was like equating an apple to an orange.” He wanted to know what level of reduction in resistance FDA expected would occur for humans if the proposed FDA guidance went into effect.

FDA Principal Deputy Commissioner Joshua Sharfstein, MD, said that FDA expects that if the proposed draft guidance is followed as written that antibiotic resistance would be reduced in humans and animals, though he could not estimate the reduction.

Shimkus wanted to know whether there was any US study to support this analysis. Sharfstein cited an Institute of Medicine study.

Other committee members stated that they believed the evidence supporting the link and that action must be taken. Rep Henry Waxman, D-CA, chairman of the House Energy and Commerce Committee, stated that the “scientific evidence is now strong enough to create consensus among major public health groups and experts around the world that the time has come to reduce the use of antibiotics in animals.”

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