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U.S. Department of Health and Human Services

Animal & Veterinary

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International Activities - Dr. Tollefson Participates in Berlin Symposium

FDA Veterinarian Newsletter November/December 2003 Volume XVIII, No 6

Dr. Linda Tollefson, Deputy Director, Center for Vet-erinary Medicine traveled to Berlin, Germany on November 8-12, 2003, to attend as an invited presenter and session chairperson at an international symposium titled "Towards a Risk Analysis of Antibiotic Resistance."

The German Federal Institute for Risk Assessment sponsored the meeting in cooperation with the Federal Office of Consumer Protection and Food Safety and the Federal Agricultural Research Centre. The development and spread of antimicrobial-resistant microorganisms and the impact of the use of antimicrobial agents in food-producing animals were the main topics. This was the fourth symposium at the Institute for Risk Assessment on the subject of antibiotic resistance, which is considered to be a serious problem all over the world. Previous symposia were held in 1995, 1997, and 2002. The Institute considers the ban on the use of antimicrobial growth promoters in the European Union from 2006 onwards to be the fruit of these efforts and the first step toward controlling antimicrobial resistance. All growth-promoting antimicrobials that are of drug classes also used in human medicine have already been banned in the EU and all remaining growth-promoting antimicrobials will be removed as of January 1, 2006.

The purpose of the symposium was to present the newest research demonstrating adverse health effects on humans from the use of antimicrobial agents in food-producing animals. A secondary purpose was to identify additional risk management strategies that could be implemented to restrict usage of antimicrobials in food-producing animals to only those situations where an infectious disease has been identified. Scientists at the meeting stated that improvement of husbandry conditions, consistent hygiene, and the increased use of vaccines were alternatives to the use of antimicrobials in food-producing animals, particularly when it came to the treatment of entire herds in which only some animals were sick.

Dr. Tollefson presented the Center's Guidance for Industry #152, "Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to their Microbiological Effects on Bacteria of Human Health Concern," which uses a risk-based approach to evaluate human food safety with respect to antimicrobial resistance prior to approval of the drug for use in food-producing animals. She also co-chaired a session with Dr. Helmuth Tschäpe of the Robert Koch Institute on "Hazard Characterization." Drs. Tollefson and Tschäpe also led a working group on the topic and developed a report.

The symposium was attended by approximately 200 scientists from 16 countries. The participants included several representatives of international organizations including the World Health Organisation (WHO), the Food and Agriculture Organization (FAO) and the Office International des Epizooties (OIE). The participants in the symposium advocated taking all possible steps to reduce the risk of resistance development. The focus at this symposium was on reducing the use of antimicrobial agents in animal production and veterinary medicine. The participants expressly pointed out that this recommendation does not apply to treatment; sick animals must be treated. The scientists concurred that actions taken to mitigate resistance will also help maintain the effectiveness of antimicrobial agents used in veterinary medicine.

There was a great deal of discussion on the prophylactic or "metaphylactic" use of antimicrobials involving the treatment of an entire herd or flock as a precautionary measure after individual animals show signs of illness. Because the dosage in this type of treatment varies considerably such that individual animals may receive sub-optimal amounts of the drug, the practice can facilitate the development of resistant organisms. The Scandinavians have shown that there is potential for curtailing the use of antimicrobials for these purposes. They were able to markedly reduce the use of antimicrobials in swine and poultry production and provide evidence of a decline in resistance without the number of sick animals increasing.

More detailed information on this subject can be accessed on the Federal Institute for Risk Assessment home page (www.bfr.bund.de) under Food/Food Safety/Microbial risks or using the search keyword "Resistance."

The Institute for Risk Assessment plans to incorporate the information from this symposium into its overall assessment of risks resulting from the use of antibiotics in food-producing animals.