الفهرس 
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Abstract
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. Most of the cells were dead or indicated cytopathic changes, effect of isolates on embryonated chicken
eggs (SPF) found they cause death to embryos within the 12 days post injection in a percent 80- 100 %. The
in vitro sensitivity of 86 E.coli isolates were conducted against 15 antimicrobial drugs, results revealed all
sensitive strains for each of Colistin and Trimethoprim while 100% resistance to oxytetracycline and
streptomycin
Polymerase chain reaction of 8 of genes (papC) and (uidA) and kpsMT II and iss and ompA and iroN and
eaeA and ibeA for the detection of virulence factors associated with poultry. And the study showed the
presence uidA gene in all isolates tested 100% And have shown that the most prevalent is the iss gene and a
ratio of 94.2 % and followed omp A and a ratio of 86.6 % exists then eae A and existing percentage of 50.8
%, while no ibe A gene could be found in this study