December 23, 2009

Canadian study finds drug-resistant E. coli in chicken litter

Chicken litter is a source of antimicrobial residues and is a reservoir of multiple antibiotic-resistant E. coli.

Veterinary pharmaceuticals are commonly used in poultry farming to prevent and treat microbial infections as well as to increase feed efficiency, but their use has created public and environmental health concerns.

Canadian researchers investigated the veterinary pharmaceuticals and antibiotic resistance of E. coli isolates in poultry litter from commercial farms and controlled feeding trials.

Litter samples were collected from controlled feeding trials and from commercial farms. The study confirmed the presence of antimicrobial residues in broiler litter from controlled environments as well as commercial farms, ranging from 0.07 to 66 mg/L depending on the compound.

Concentrations of individual residues were higher in litter from controlled feeding trials than those from commercial farms. All E. coli isolates from commercial farms were multi-resistant to at least seven antibiotics. Resistance to beta-lactam antibiotics (amoxicillin, ceftiofur), tetracyclines, and sulphonamides was the most prevalent trait.