The Mounting Scientific Case Against Animal Use of Antibiotics
The role of drug use in livestock in eliciting antibiotic resistance in disease-causing bacteria like Campylobacter and Salmonella, which originate from farm animals and are transmitted to humans on food, has been well documented. New scientific evidence, however, suggests that resistant food-borne infections may be only one of the health threats from the use of antibiotics in animal operations. Recent studies indicate that antibiotic drug use on the farm may contribute to resistance problems in diseases other than the traditional food-borne illnesses and that bacteria may move from the farm to the community in ways other than on food. Below are brief summaries of three recent scientific articles supporting these points.
New Diseases: Urinary Tract Infections
Manges et al. 2006. The changing prevalence of drug-resistant Escherichia coli clonal groups in a community: evidence for community outbreaks of urinary tract infections. Epidemiology and Infection 134(2):425-31.
Growing evidence suggests that antibiotic use in farm animals is a cause of resistant E. coli infections (along with antibiotic use in humans, a long recognized cause). Manges et al. provide evidence that some antibiotic-resistant urinary tract infection (UTI) outbreaks may be caused by food contaminated with E. coli. Although most E. coli do not cause illness, certain strains can infect the urinary tract, kidneys, blood and other tissues. These strains cause millions of infections each year, including the bulk of the four million community-acquired (UTIs) treated in the United States each year.
New Diseases: Methicillin-resistant Staph Aureus (MRSA)
Soil Association. 2007. MRSA in farm animals and meat: A new threat to human health.
Methicillin-resistant Staphylococcus aureus (MRSA) is a cause of serious infections in both hospitals and communities. Recent studies from Europe collected in a report from the Soil Association show that livestock producers are at greater risk of carrying MRSA. Livestock-derived MRSA strains have also been shown to contaminate foods and cause human illness.
New Pathways for Transmission: Farm Workers
Akwar et al. 2007. Risk factors for antimicrobial resistance among fecal Escherichia coli from residents on forty-three swine farms. Microbial Drug Resistance 13(1):69-76.
Akwar et al. found that people living and working on swine farms where antibiotics were used in feed had increased chances of carrying resistant E. coli. In some cases, the risk of resistance for the farm workers was higher than if they had taken antibiotics themselves. Once farm workers are colonized by resistant bacteria they can transfer them to family members and others in their community.