Abstract
Present study was conducted on 200 fecal samples of broilers chickens suffering from colisepticemia from poultry farms in Riyadh, Saudi Arabia. Escherichia coli strains were isolated from 88 (44%) samples. Out of E. coli strains, 79 (89.77%) belonged to O126: K71, O158: K-, O114: K90, O111: K58, O78: K80 and O119: K69. Whereas, O126: K71, O158: K-and O114: K90 were the most prevalent. The antibiotic sensitivity pattern showed that all isolates were totally resistant to ampicillin. chloramphenicol and streptomycin (100%). Resistance against erythromycin and naldixic acid reached 81.01 % and was recorded in 20 strains O126: K71, 17 strains O158: K-, 15 strains O114: K90, 12 strains O111: K58, and decrease to 78.48% against ciprofloxacin in O126: K71, O114: K90, O111: K58, O78: K80 and O119: K69 strains. It should note that the recovered isolates were 84.81% intermediate to cephalexin and 53.16% sensitive gentamycin. This study highlights the high resistance of E. coli to antibiotics constitutes a threat to poultry industry in Saudi Arabia and the need for continuous surveillance of antibiotic sensitivity pattern of E. coli with a view to selecting appropriate therapy.