Abstract
Escherichia coli (E. coli) was isolated from broiler chickens from El-Behera governorate. This study was aimed to detect the incidence of five virulence genes and the antibiotic resistance pattern of isolated E.coli. A total of 66 E. coli isolates were isolated from the liver, heart, kidney, and oviduct from broilers suffered from perihepatitis, pericarditis, omphalitis, salpingitis. The isolates were tested for pathogenicity using 5% sheep blood agar and showed 80.3% of the isolates gave alpha hemolysis and 19.7% give beta hemolysis. The isolates were examined for their sensitivity to ten antibiotics. They showed high sensitivity to ciprofloxacin with a percentage of 53.03%, while Ampicillin and Amoxicillin show a higher resistance with a percentage of 59.09% and 56.06%, respectively. On the other hand, the isolates were moderately sensitive to Nitrofurantoin, Neomycin, Tetracycline, Gentamycin, Cephalexin, Kanamycin and Chloramphenicol with percentage 87.87%, 83.33%, 83.33%, 74.25%, 72.72%, 59.09%, and 57.57%, respectively. PCR was performed using PhoA gene for the detection of E. coli that was detected in 31.81% of isolates. PCR also used for detection of five virulence genes PapC, IutA, FimH, Iss, fyuA gene, which were detected in 42.85%, 9.53%, 47.6%, 57.14%, and 33.33%, respectively. It could be concluded that the most effective antibiotic was Ciprofloxacin and avoid using ampicillin and amoxicillin because of the high resistance of bacteria against those antibiotics. The most prevalent gene was Iss which responsible for serum resistance of bacteria followed by FimH, PapC gene which were responsible for adhesion of bacteria.

Key words: E. coli , PCR, APEC, Antibiotics , Virulence genes