الفهرس 
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Abstract
This study was conducted to determine the presence of E.coli spp.
in raw milk samples collected from North Sinai Governorate. E.coli
isolated from farm milk with a percentage of 10%, from market milk;
11.7% (as from dairy shops and groceries; 12% and from the vendors
11%), with total isolation percentage 8.9%.
Sero grouping of E.coli isolates(n:10) revealed the detection of
serogroups:O1(2strains),O6(2strains),O55(1strain),O86(1strain),O12
8(2strains) and O158(2strains); distributed as O1 and O55 from farm
milk,O6,O86,O128 and O158 from market milk and O1,O128 and
O158 from the vendor’s milk.
40% of E.coli strains showed positivity for Congo red dye binding
activity test.
The antibiogram of E.coli strains performed by using the VITEK 2
apparatus. E.coli strains revealed 100% resistance towards
Ampicillin, 80% for Tetracycline, 50% for piperacillin, 40% for
Cephalexin, Chloramphenicol and Trimethoprime-Sulfamethaxol.
The PCR used for detection of ” phA ”gene in E.coli strains, the
results revealed that all E.coli harbored the sequence of that
gene(100%).Also the occurrence of virulence genes (stx1,stx2) were
analyzed .the results showed that all E.coli strains were devoid of stx1
and only one E.coli strain(O158) carried the stx2 gene.
The antibiotic resistance genes were determined in E.coli strains
As the ”tetA”gene was detected in 80% of E.coli strains and the
”blaTEM” gene was detected in 100% of E.coli strains.