title: Antibiotic resistance, phylogenetic grouping and virulence potential of Escherichia coli isolated from the faeces of intensively farmed and free range poultry.
abstract: Antibiotic use in poultry production is a risk factor for promoting the emergence of resistant Escherichia coli. To ascertain differences in different classes of chickens, the resistance profile, some virulence genes and phylogenetic grouping on 251 E. coli isolates from intensive meat (free range and indoor commercial) and free range egg layer chickens collected between December 2008 and June 2009 in South Australia were performed. Among the 251 strains, 102 (40.6%) and 67 (26.7%) were found to be resistant to tetracycline and ampicillin respectively. Resistance was also observed to trimethoprim-sulfamethoxazole (12.4%), streptomycin (10.8%), spectinomycin (9.6%), neomycin (6.0%) and florfenicol (2.0%) but no resistance was found to ceftiofur, ciprofloxacin or gentamicin. Amplification of DNA of the isolates by polymerase chain reaction revealed the presence of genes that code for resistant determinants: tetracycline (tet(A), tet(B) and tet(C)), ampicillin (bla(TEM) and bla(SHV)), trimethoprim (dhfrV and dhfrXIII), sulphonamide (sulI and sulII), neomycin (aph(3)-Ia(aphA1)), and spectinomycin-streptinomycin (aadA2). In addition, 32.3-39.4% of the isolates were found to belong to commensal groups (A and B1) and 11.2-17.1% belonged to the virulent groups (B2 and D). Among the 251 E. coli isolates, 25 (10.0%) carried two or more virulence genes typical of Extraintestinal pathogenic E. coli (ExPEC). Furthermore, 17 of the isolates with multi-resistance were identified to be groups B2 and D. Although no significant difference was observed between isolates from free range and indoor commercial meat chickens (P>0.05), significant differences was observed between the different classes of meat chickens (free range and indoor commercial) and egg layers (P<0.05). While this study assessed the presence of a limited number of virulence genes, our study re emphasises the zoonotic potential of poultry E. coli isolates.
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia.
authors.forename: Akua Serwaah
authors.initials: AS
authors.lastname: Obeng
authors.forename: Heather
authors.initials: H
authors.lastname: Rickard
authors.forename: Olasumbo
authors.initials: O
authors.lastname: Ndi
authors.forename: Margaret
authors.initials: M
authors.lastname: Sexton
authors.forename: Mary
authors.initials: M
authors.lastname: Barton
mesh_terms: D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D002645:Chickens / Q000382:microbiology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000235:genetics; D005243:Feces / Q000382:microbiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D011200:Poultry / Q000382:microbiology; D013021:South Australia; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology; D014774:Virulence / Q000187:drug effects / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors; D015662:Trimethoprim, Sulfamethoxazole Drug Combination