be terminated in the absence of risk-based evaluations (WHO, 1997, 1999, 2000).

Several European countries have already taken steps toward this goal. In 1998, the European Union banned four growth promoters (tylosin, spiramycin, bacitracin, and virginiamycin) because of their structural relatedness to antimicrobial agents used in human medicine (European Commission, 1998). In that same year, chicken farmers and beef producers in Denmark voluntarily stopped using antimicrobial agents as growth promoters; swine farmers followed suit in 1999. This ban has reduced the total volume of antibiotics used in food animals in Denmark by 60 percent (from 206 to 81 tons) (DANMAP, 2000; Sorensen et al., 2002). Studies to investigate the influence of the ban have shown no negative consequence for farmers’ profits or animal health in broiler chickens (Emborg et al., 2001). Similar conclusions were reported in fattening pigs, although diarrhea in weaned piglets has required other interventions, such as improved feeding and weaning procedures (Sorensen et al., 2002). In Sweden, all antibiotics were banned as growth promoters in 1986, decreasing their total antibiotic usage by 55 percent and demonstrating their ability to achieve competitive production results in the absence of growth promoters (Wierup, 1998; Greko, 1999). The effects of discontinuation of growth promoters in these countries have been a decrease in antibiotic resistance in animals, food products, and humans (Bager et al., 1999; Klare et al., 1999; Pantosti et al., 1999; DANMAP, 2000; van den Bogaard et al., 2000a; Aarestrup et al., 2001).

Clinicians should be aware that antimicrobial resistance is increasing in foodborne pathogens such as Salmonella and Campylobacter and that patients who are taking antimicrobial agents for any reason are at increased risk for acquiring antimicrobial-resistant foodborne infections. The increasing prevalence of antimicrobial resistance among these pathogens increases the potential for treatment failures and other adverse outcomes, including death. Appropriate use of antimicrobial agents in humans and food animals is necessary to maintain their effectiveness and reduce the potential for spread of resistant organisms. While therapeutic usage of antimicrobial agents in food animals is important to promote animal health and provide an affordable supply of meat, milk, and eggs, it is vital that the long-term effectiveness of antimicrobial agents used in human medicine be preserved. This report presents current surveillance information on the frequency of resistant foodborne infections in the United States, reviews scientific evidence linking antimicrobial agent usage in agriculture to resistant foodborne infections in humans, and makes recommendations for measures to protect public health.

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