Molecular characterisation of <i>Escherichia coli</i> from dead broiler chickens with signs of colibacillosis and ready-to-market chicken meat in the West Bank

1. The aim of this work was to compare a group of virulence-associated characteristics of <i>Escherichia coli</i> isolates from broiler chickens that had died with signs of colibacillosis against <i>E. coli</i> isolates from ready-to-market chicken meat in the West Bank.2. The isolates were investigated to determine the virulence factor (VF) profile, phylogenetic group and the presence of extended-spectrum beta-lactamase (ESBL). A total of 66 avian pathogenic <i>E. coli</i> (APEC) strains from different affected broiler farms and 21 <i>E. coli</i> isolates from ready-to-market chicken carcasses (hereinafter called meat strains) from 8 slaughter houses were analysed.3. The overall content of VFs was significantly higher (<i>P 0.05) among APEC strains, with over 75% of APEC strains having ≥4 VFs, while over 75% of the meat strains had &lt;4 VFs. The VFs <i>iss, astA</i> and <i>iucD</i> were frequently detected in APEC and meat strains, whereas <i>cvi, papC, vat, tsh</i> and <i>irp2</i> occurred more significantly in APEC strains. Phylogenetic typing showed that 67% of the meat strains belonged to group B2. Phylogroup D was predominant (50%) in the APEC strains. Using double disc diffusion and polymerase chain reaction (PCR), 10.6% of the APEC and 9.5% of the meat strains were determined to be ESBL positive.</i>4. Our findings show that the VFs <i>papC, vat, irp2</i> and to a lesser extent <i>tsh</i> and <i>cvi</i> are significantly more prevalent in APEC strains. The results demonstrate that chicken meat can be contaminated with APEC strains (≥4 VF). A significant percentage of the meat strains fall in the B2 group, which is a phylogroup largely associated with human pathogenic ExPEC strains. The results of ESBL screening indicated that broiler chicken products in Palestine represent a potential reservoir of ESBL genes and therefore could be considered a possible public health risk.