الفهرس 
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Abstract
Escherichia coli bacteria are normal inhabitant in the intestine of man, animals and poultry. A total of 20 isolates of E. coli, isolated from diseased chickens belonged to different O-serogroups and showed resistance to one or more antibiotics, were investigated for antimicrobial resistance against β-lactam and quinolone groups of antibiotics and tested for detection of plasmid mediated quinolone and β-lactam resistant genes. The result was resistance of 60% of the isolates to ampicillin and amoxicillin (β-lactam group) and 95%, 85%, 80%, 45% and 20% to enrofloxacin, norfloxacin, naldixic acid, danofloxacine and ciprofloxacin (quinolone group), respectively. All the selected isolates showed multi-resistance when they were tested against 8 antibiotic groups. Among the twenty E. coli isolates tested, 6 (30%) isolates were positive for the qnr genes, where 5 (25%) isolates were positive for qnrS gene; one of them was positive for qnrB gene and only one isolate carried qnrA gene. All the E. coli isolates were negative for aac(6’)-Ib-cr gene. On the other hand, the qepA gene was the most commonly found in the PMQR genes, as it was detected in 14 (70%) E. coli isolates. All qnr positive isolates carried the qepA gene. The β-lactam resistant gene (blaTEM) was detected in 16 (80%) of the isolates; while the blaSHV gene was detected only in one isolate. There was a high correlation between the presence of the qepA gene and resistance to ENR, NA, and NOR, as well as between blaTEM gene and resistance to AML and AMP.