Identification of colicinogenic Escherichia coli isolates from broiler car-casses and their inhibitory effect on E. coli pathotypes

Colicins are antibacterial compounds produced by Escherichia coli which give the producing strains the ability to compete ecologically against other bacteria. The aim of this study was to identify Escherichia coli strains producing colicin isolated from broiler carcasses by PCR and to investigate the inhibitory effect of colicinogenic strains on different Escherichia coli pathotypes. In this study, swab sample was obtained from 110 carcasses of broiler carcasses slaughtered in Kerman industrial slaughterhouse. one confirmed Escherichia coli isolate was selected from each carcass. Seven groups of colicin genes including Y.U, E1, V, 5.10.K, E2-9, Ia.Ib and A.N.S4 were screened using PCR and specific primers. Strains containing at least one colicin encoding gene were studied for their inhibitory effect on the growth of various Escherichia coli pathotypes. In this study, out of 110 isolates, 54 isolates (49.1%) were positive for at least one of the studied genes. Of the total samples, 33 isolates (30%) were positive for Ia.Ib gene. Also, V and E1 genes with frequencies of 20% (22 isolates) and 9% (10 isolates) were in the next ranks, respectively. The prevalence of A.N.S4 gene was 2.9% (3 isolates) and E2-9 and 5.10.K genes were only detected in 1 isolate (0.9%). The U.Y gene group was not detected in this study. Among 54 isolates with colicin genes, 18 isolates (33.3%) had an inhibitory effect on at least one of the ETEC, EIEC, EHEC, EAEC and EPEC patotypes. Phenotypically, the most inhibitory effect of colicinogenic strains was observed on ETEC and EAEC pathotypes.