Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

in this study, 90 tested flocks were collected from different sources of poultry ( grandparents and layers and broilers and broiler breeders ) of suspected E. coli septicemia in Egypt . Based on the obtained results, it was found that the prevalence of E.coli infection 95.6 %. The 86 serotypes were distributed as 16 (18.16%) of serotypes O125:K70, 12 (13.95%) of serotypes O158:K-, 10 (11.62%) of serotypes O44:K74 and O114:K90 each, 9 (10.46%) of untypable isolates, 6 (6.97%) of serotypes O91:K-, 4 (4.48%) O111:K58, O78:K80 and O25:K11, 2 (11.62%) of serotypes O103:K- and O26:K60 and finally the lowest percentage 1 (1.16%) were detected in serotypes O86: K- and O127:K63 Testing of the phynotypic properties of the 86 isolates it was found that all tested E. coli isolates were Congo red positive but with different intensities , the isolates tested were positive in their motility test and haemolysis assay (100%), results showed that the two cell lines MDCK and Vero cells were infected with E. coli

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