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U.S., Canadians, Europeans Endorse Restricted Animal Antimicrobial Uses
Officials at the Food and Drug Administration (FDA) in September proposed guidelines, which are meant to curb the development of antibiotic resistance, for restricting antimicrobial drug use in animals. Separately, an advisory panel in Canada released a draft report recommending broadly similar measures to block antibiotic resistance by restricting antimicrobial uses in animals. And in yet another development, a European court upheld an earlier order banning several antimicrobials from use in animal feeds.
"The primary focus" of the proposed new FDA guidelines, according to agency officials, is on concerns that new antimicrobial drugs, when used in food-producing animals, will "cause resistance determinants or resistant bacteria to emerge" and that they will lead to adverse human health effects. "FDA's overriding concern is that the effectiveness of antimicrobial drugs is decreased or lost in humans as a consequence of human exposure to resistant bacteria (or resistance determinants) resulting from the use of antimicrobial drugs in food-producing animals." In addition, officials plan to reevaluate antimicrobials that are already being used in veterinary medicine by means of a "risk analysis process" for their potential to contribute to antimicrobial resistance problems. The docket for formal comments regarding the new guidelines will be open until late November.
These guidelines began to take shape several years ago when officials in the FDA Center for Veterinary Medicine proposed a major new framework for evaluating antimicrobial drugs—one that met with immediate controversy (ASM News, April 1999, p. 194). Initial responses to the revised guidelines suggest that the controversy persists.
"Some of the details of this proposal are unnecessarily stringent and will make it very difficult for new antibiotic products to be approved, thus creating new animal health and food safety risks while not adding to public health," says Alexander S. Mathews, who is president of the Animal Health Institute in Washington, D.C. "Antibiotics have been used in animal husbandry for more than 40 years. [and] judicious use principles, the use of risk assessment, surveillance, and local intervention have all worked to enable producers to safely use these products while minimizing the threat of antibiotic resistance."
"The [FDA] guidance document contains less than two pages on reevaluating the safety of already-approved agricultural antibiotics," says Karen Florini of Environmental Defense and a member of a coalition, Keep Antibiotics Working (KAW), whose members say that they are particularly concerned with the FDA focus on new antimicrobial drug candidates rather than on those drugs that already are being used in agriculture.
"Even more troubling is the lack of any timetable for completing, or even initiating, such reevaluations," Florini says of the FDA guidelines. "Congress needs to take action to get the ball moving much faster." Legislative proposals introduced earlier this year, one by Sen. Edward M. Kennedy (D-Mass.) and the other by Rep. Sherrod Brown (D-Ohio)—designated S. 2508 and H.R. 3804, respectively—propose phasing out the routine feeding of medically important antibiotics to healthy farm animals two years after enactment unless FDA determines that continuing such use would not contribute to antibiotic resistance in humans (ASM News, May 2002, p. 208).
A similar debate is under way in Canada. In 1999, Health Canada established the Advisory Committee on Animal Uses of Antimicrobials and Impact on Resistance and Human Health. Its recently released report concludes that, although the "magnitude of the public health impact is unknown, resistance is a serious problem in bacterial infections of humans originating from animals" and these "problems warrant changes to the ways that antimicrobials are regulated, distributed, and used in animals." Its key recommendations include:
make antimicrobials available by prescription only;
evaluate and register all antimicrobials used in food animals;
evaluate antimicrobials for growth promotion or feed efficiency using sound risk analysis principles; and
design and implement a national surveillance system for antimicrobial resistance arising from food animal production.
Meanwhile, in September the European Court of Justice rejected an appeal over a lawsuit brought by Pfizer and Alpharma. The companies are seeking to overturn a European ban on several antibiotics, including virginiamycin and bacitracin zinc, that were used as growth promoters in poultry feed before it went into effect in 1999. "Despite uncertainty as to whether there is a link between the use of those antibiotics as additives and the development of resistance to them in humans, the ban on the products is not a disproportionate measure by comparison with the objective pursued, namely the protection of human health," the members of the Court concluded in ruling on that appeal. The companies have until mid-November to appeal to the Court of Justice of the European Communities.
Jeffrey L. Fox
Jeffrey L. Fox is the ASM News Current Topics and Features Editor.
Email: webmaster@asmusa.org