ScienceDaily (Nov. 15, 2011) — In a review study, researchers from Tufts University School of Medicine zero in on the controversial, non-therapeutic use of antibiotics in food animals and fish farming as a cause of antibiotic resistance. They report that the preponderance of evidence argues for stricter regulation of the practice. Stuart Levy, an expert in antibiotic resistance, notes that a guiding tenet of public health, the precautionary principle, requires that steps be taken to avoid harm.

"The United States lags behind its European counterparts in establishing a ban on the use of antibiotics for growth promotion. For years it was believed that giving low-dose antibiotics via feed to promote growth in cows, swine, chickens and the use of antibiotics in fish farming had no negative consequences. Today, there is overwhelming evidence that non-therapeutic use of antibiotics contributes to antibiotic resistance, even if we do not understand all the mechanisms in the genetic transmission chain," says Levy, MD, professor of molecular biology and microbiology and director of the Center for Adaptation Genetics and Drug Resistance at Tufts University School of Medicine.

For the past 70 years, humans have relied on antibiotics to combat bacterial infections such as streptococcus, meningitis, tuberculosis and urinary tract infections. The misuse and overuse of antibiotics, however, has contributed to antibiotic resistance, making antibiotics less effective at saving lives. Levy and co-author Bonnie Marshall summarize and synthesize the findings of a large number of studies assessing the link between antibiotic resistance and the use of non-therapeutic antibiotics in livestock and fish farming. Highlights include the following.