Frequency of some virulence associated genes among multidrug-resistant Escherichia coli isolated from septicemic broiler chicken

Avian pathogenic E. coli (APEC), the causal organism of infection in chickens, is responsible for large economic losses in the poultry industry in Egypt and worldwide. In this study 83 E. coli isolates were recovered from 200 broiler chicken suffering from colibacillosis. The disc diffusion method was used to determine antibiotic susceptibility of the isolates to 10 antibiotics comprising 6 different antimicrobial classes. Many isolates 75 (90.4%) exhibited resistance to 3 or more of the tested compounds and were defined as multiple drug resistant (MDR). Antibiogram profiles indicated maximum resistance to ampicillin (100%), high frequency of resistance to amoxicillin (97.6%), sulfamethoxazole/trimthoprim (94%), streptomycin (92.8%) and ciprofloxacin (89.2%). Conversely, the aminoglycoside amikacin was still effective against 97.6% of the isolates. Some MDR isolates (n = 40) were selected for serogrouping and 9 different serogroups were detected among them. The previously selected isolates (n = 40) were screened for presence of some virulence associated genes (iutA, hlyF, iss, iroN and ompT) using a pentaplex PCR. There was a high prevalence for such genes among the tested isolates except for iutA gene, which was harbored by only 5% of the tested isolates.