A total of 100 diseased broiler chickens of average age 22-28 days old were collected from different farms located in Dakahlia Governorate. All samples were subjected to clinical and postmortem (P.M) examination as well as bacteriological examination for detection of infection. Thus, E. coli was recovered from examined organs of 37 chickens with an incidence rate of 37 % (37 out of 100). Accuratly, 10 E. coli serogroupes were identified in 28 positive samples and the most predominant serogroup were O₁₂₅ 16%, O₉₁ 14%, O₁ 11%, O₂₆ K₆₀ 11% & O₈₆ K₆₄ 8 & O₁₂₈ 5% & O₅₅ K₅₉ 3% & O₁₆₆ 3% & O₁₀₃ 3% and O₁₄₄ 3% and untypable E. coli (24 %). Studying antibiogram resistance pattern of E. coli isolates revealed that all isolates demonstrated multidrug resistence pattern. The highest resistance rates were recorded against Lincomycin (100%) and lowest are Colistin (7.14%) and other tested antibiotics showed variations regarding their resistance patterns. The most predominant serotypes of this study have the ability to form biofilm on the inner wall of the glass. PCR was done for detection of resistant genes (bla_TEM and tetA(A)) and virulence genes (csgD, adrA, eaeA and fimH) in the 10 tested isolated serotypes and the results revelead that, 100% and 90% &100%, 90%, 90% and 100% were positive for resistant genes and virulence genes, respectively and investigate the relationship between them was discovered. By studying the effect of Olive Leaf Extract on multidrug resistant isolates, results were revealed that all tested serotypes are sensitive to Olive Leaf Extract (10% conc.).