Study Finds Common Food Poisoning Bacteria Found on Broiler Carcasses Routinely Fed Antibiotics Are Resistant to Human Drug
Washington, DC - A new study published in the June 1 issue of Poultry Science showed that all of the Campylobacter bacteria isolated from the carcasses of broiler chickens that
had been routinely fed doses of tylosin to promote growth were resistant to the nearly chemically identical human drug erythromycin. The study by researchers at the U.S.
Department of Agriculture (USDA) also showed that none of Campylobacter on birds fed a diet without tylosin carried these same resistance traits.
"Erythromycin is increasingly important for treatment of food poisoning in humans and as an alternative to penicillin in people who have penicillin allergies," said Margaret
Mellon, Ph.D., director of the Food and Environment Program at the Union of Concerned Scientists. "This new study strengthens the already strong evidence that the
use of non-therapeutic antibiotics in poultry and livestock leads to resistance to identical and similar drugs important in human medicine."
The study also suggests that broiler carcasses may carry a lower level of Campylobacter as a result of the tylosin treatment. Samples drawn at one of three stages of processing showed reduced levels, while the samples at the other two stages did not.
But according to David Wallinga, M.D., director of the Food and Health Program at the Institute for Agriculture and Trade Policy, "reductions in overall Campylobacter levels, even if confirmed by further studies, would be not be worth much if the residual bugs are all resistant to antibiotics."
Campylobacter causes more than 2 million illnesses each year in the United States. Resistant Campylobacter, which commonly contaminates retail poultry products, leads to human infections caused by bacteria that are more virulent and costly to treat than are their antibioticsusceptible
counterparts. Tylosin is one of the most common antibiotics routinely fed to poultry for growth promotion.
Preserving the effectiveness of erythromycin as treatment for serious food borne illness is increasingly important because resistance has eroded the effectiveness of other frontline drugs, like Cipro. In 2005, the FDA banned the use of a Cipro-like antibiotic, Baytril, in poultry flocks because its therapeutic use in chickens had led to a rise in Cipro-resistant Campylobacter infections in people.
Reference: Berrang et al. 2007. Subtherapeutic Tylosin Phosphate in Broiler feed Affects Campylobacter on
Carcasses During Processing. Poultry Science 86:1229-1233.