Characterization of extended-spectrum beta-lactamase-producing fecal Escherichia coli isolates in laying hens

The purposes of the present study were to determine whether healthy laying hens in Burdur province of Turkey carried extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in their intestinal flora and to further characterize the E. coli isolates and ESBL genes. A total of 200 fecal samples from three laying hen farms were cultured in Brilliance E. coli / coliform Selective Agar supplemented with cefotaxime or ceftazidime. ESBL-producing E. coli isolates determined by phenotypic tests were screened by Polymerase Chain Reaction (PCR) for ESBL genes, and ESBL genes were sequenced. Phylogenetic analysis of the E. coli isolates were performed by PCR. ESBL-producing E. coli were isolated from 12 (6.0%) laying hen fecal samples by phenotypic tests. According to PCR screening and sequence analysis, bla(CTX-M) group 1 (bla(CTX-M-3) or bla(CTX-M-15)) genes were detected in the E. coli isolates. Phylogenetic analysis of the E. coli isolates showed that group D was the predominant group (58.3%) and none of the isolates belonged to group B2. Consequently, present study reports the first characterisation of CTX-M-3 and CTX-M-15 type ESBL-producing E. coli isolates on laying hen production from Turkey.