title: Comparison of antimicrobial resistance patterns in enterococci from intensive and free range chickens in Australia.
abstract: Resistance to antimicrobials in enterococci from poultry has been found throughout the world and is generally recognized as associated with antimicrobial use. This study was conducted to evaluate the phenotypic and genotypic profile of enterococcal isolates of intensive (indoor) and free range chickens from 2008/09 and 2000 in order to determine the patterns of antimicrobial resistance associated with different management systems. The minimum inhibitory concentrations in faecal enterococci isolates were determined by agar dilution. Resistance to bacitracin, ceftiofur, erythromycin, lincomycin, tylosin and tetracycline was more common among meat chickens (free range and intensive) than free range egg layers (P<0.05). Isolates were evaluated by polymerase chain reaction for bacitracin (bcrR), tylosin (ermB), tetracycline (tet(L), tet(M), tet(O), tet(S), and tet(K)), gentamicin (aac6-aph2), vancomycin (vanC and vanC2), ampicillin (pbp5) and integrase (int) genes. Resistance to bacitracin, erythromycin and tetracycline were found to be correlated with the presence of bcrR, ermB, and tet genes in most of the isolates collected from meat chickens. Most bacteria encoding ermB gene were found to express cross-resistance to erythromycin, tylosin and lincomycin. No significant difference was found in these resistance genes between isolates sampled in 2000 and 2008/09 (P<0.5). Unlike the enterococcal strains sampled in 2000, the 2008/09 isolates were found to be susceptible to vancomycin and virginiamycin. This study provides evidence that, despite strict regulation imposed on antibiotic usage in poultry farming in Australia, antimicrobial resistance is present in intensively raised and free range meat chickens.
authors: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide 5000, South Australia, Australia.
authors: Akua Serwaah
authors: AS
authors: Obeng
authors: Heather
authors: H
authors: Rickard
authors: Olasumbo
authors: O
authors: Ndi
authors: Margaret
authors: M
authors: Sexton
authors: Mary
authors: M
authors: Barton
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001483:Base Sequence; D002645:Chickens / Q000382:microbiology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016983:Enterococcus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005798:Genes, Bacterial / Q000235:genetics; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013021:South Australia
chemical_list: D000890:Anti-Infective Agents