Colibacillosis constituted as one of the most important disease condition affecting poultry with
significant implications on production. Herein, examination of 451 organ samples including trachea,
lung, heart blood, liver and spleen collected from freshly slaughtered chickens using standard methods
for isolation and identification of E. coli showed that 236 samples were positive for E. coli with an
incidence rate (52%). Twenty-five E. coli strains were serogrouped and 6 different serogroups were
successfully identified, the most prevalent serogroup was O78 (20%), followed by O157 and O27 with
incidence rate (16%) for each, O168 and O125 (12%) each. and finally O115 (8%), in addition to 4
untypable strains. The antibiotic susceptibility of 60 isolates against ten antimicrobials was performed
by disc diffusion method and the results revealed that gentamicin and colistin were the most effective
antibiotics on the isolates. On the other hand, all isolates exhibited absolute resistance to erythromycin
and rifampicin, followed by high level of resistance ranging from (75-95%) for ciprofloxacin,
sulfamethoxazole–trimethoprim, cefoxtin, chloramphenicol, doxycycline and amoxicillin- clavulanic
acid. All isolates exhibited multidrug resistance phenotypes