Abstract
Colibacillosis is a major disease affecting poultry leads to high morbidity and mortality which causing tremendous economic losses worldwide. These economic disparities are amplified among low and middle-income where sanitation and hygiene are challenged by the increasing demand for quality sources of animal protein. With a view to investigating the prevalence of virulence genes and QACs resistance genes as well as monitoring the antibiogram of E. coli strains, a total of 368 specimens were collected from diseased broiler chickens (n = 226) and environmental sources (n = 142) at large-scale poultry farms in Ismailia Governorate, Egypt. The bacteriological examination proved that E. coli prevalence was 26.76% and 50.44% in the farm environment and diseased broilers, respectively. In tandem, the isolated E. coli strains were serogrouped, determining the most common serotypes were O78, O1:H7, O91:H21 and O126. Isolates were tested for antimicrobial susceptibility against 12 antibiotics, screened for 4 virulence genes (iss, papC, eaeA, and cfaI), and screened for 3 QACs resistance genes (qacE Delta 1, qacA/B, and qacC/D). All the tested strains were positive for iss and papC genes, only 20.3% of the tested strains were positive for eaeA gene, moreover, the examined strains were negative to CFAI gene. Furthermore, all the tested strains were positive for qacE.1, qacA/B, and qacC/D genes. In conclusion; virulence genes (iss, papC) as well as QACs resistance genes are common in avian Pathogenic E. coli and environmental strains and are mainly associated with multi-drug resistance phenomena.