COLLEGE PARK, Md.—Poultry farms that have adopted organic practices and stopped using antibiotics have significantly lower levels of drug-resistant enterococci bacteria that can potentially spread to humans, according to a new study published in the journal Environmental Health Perspectives.
Researchers at the University of Maryland's School of Public Health investigated the impact of removing antibiotics from U.S. poultry farms by studying 10 conventional and 10 newly organic large-scale poultry houses in the mid-Atlantic region. They tested for the presence of enterococci bacteria in poultry litter, feed and water, and tested its resistance to 17 common antimicrobials.
While all farms tested positive for the presence of enterococci in poultry litter, feed and water as expected, the newly organic farms were characterized by a significantly lower prevalence of antibiotic-resistant enterococci. For example, 67% of Enterococcus faecalis recovered from conventional poultry farms were resistant to erythromycin, while 18% of Enterococcus faecalis from newly organic poultry farms were resistant to the antibiotic. Dramatic changes also were observed in the levels of multi-drug resistant bacteria on the newly organic farms—42% of Enterococcus faecalis from conventional farms were multi-drug resistant, compared to only 10% from newly organic farms, and 84% of Enterococcus faecius from conventional farms were multi-drug resistant compared to 17% of those from newly organic farms.
The findings demonstrate lower levels of drug-resistant bacteria on newly organic farms in the United States and suggest removing antibiotic use from large-scale U.S. poultry farms can result in immediate and significant reductions in antibiotic resistance for some bacteria.
