The use of subtherapeutic antibiotics in animal feed and its implications on human health.

Antibiotics were approved for use as animal feed additives in 1950 after it was discovered that their use increased growth rate, improved feed utilization, and reduced mortality and morbidity from clinical and subclinical infections in animals. Subtherapeutic use of antibiotics in animal feed grew extensively and concern has arisen that this "indiscriminate" use of antibiotics could lead to increased numbers of antimicrobial-resistant bacteria and ultimately compromise treatment of human bacterial infections. Three recently published studies seem to indicate that animal-to-man transmission of antimicrobial-resistant bacteria is possible. Increased debate on the continuing allowance of antibiotic feed additives has ensued. The National Resources Defense Council has recently petitioned the FDA to disallow penicillin and tetracycline use in animal feed, and legislation has been introduced in the U.S. House of Representatives that would limit the subtherapeutic use of antibiotics in animal feed. Experts have predicted that meat prices would increase and meat quality would decrease if antibiotics are disallowed as a feed additive. It is the opinion of the authors that there is no conclusive evidence at this time to support the premise that subtherapeutic use of antibiotics in animal feed poses a greater threat to human health than if antibiotic feed additives were banned.