الفهرس 
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Abstract
One hundred samples (25 each of market raw milk, farm bulk milk, kareish cheese and white soft cheese), collected from different localities in Mansoura City, and subjected to microbiological examination.Salmonella was detected in 15% (15/100) of the total examined samples with prevalence of 12% (3/25), 24% (6/25), 20% (5/25) and 4% (1/25) in raw market milk, raw farm bulk milk, kareish cheese and white soft cheese, respectively. Salmonella isolates were confirmed genetically by PCR, based on the presence of invA gene, and then the isolates were serotyped into. S. Enteritidis 33.3% (9/27) which was the most frequent, followed by S. Typhimurium 25.9% (7/27). E.coli was detected in 24% (24/100) of the total examined samples with prevalence of 12% (3/25), 16% (4/25), 48% (12/25) and 20% (5/25) in raw market milk, raw farm bulk milk, kareish cheese and white soft cheese, respectively.The mean value of coliform counts of the examined market raw milk, farm bulk milk, kareish cheese and white soft cheese were 4.18x106 ± 1.30x106,3.15x105 ± 1.42x105, 6.52x106 ± 1.39x106 and 3.61x103 ± 2.33x103 cfu/ml , respectively.Five E.coli isolates were examined serology where three isolates were showed positive results and biotypes into O26, O86a and O26. And when we performed PCR on these isolates to detect their genes. The results showed that one isolate of E.coli O26 that isolated from kareish cheese sample was positive for two target genes Stx2 and Hly while the other one that isolated from farm bulk milk samples was contained on Stx1 and Stx2 genes but E coli O86a serotype that isolated from market raw milk was positive for Stx2 gene and eaeA gene.E.coli O157 was detected in 15% (15/100) of the total examined samples with prevalence of 4% (1/25), 16% (4/25), 28% (7/25) and 12% (3/25) in raw market milk, raw farm bulk milk, kareish cheese and white soft cheese, respectively. three isolates out of five serologically examined isolates of probably E.coli O157 that were isolated from kareish cheese samples were positive and confirmed by PCR as the three isolates were showed positive to O157 rfbE gene and eaeA gene, also one isolate of the three E.coli O157 isolates was found to be positive for Stx2 and Hly genes and other isolate was positive to Stx2 with the previous genes.Staphylococci was detected in 80% (80/100) of total examined samples. The highest mean value of Staphylococci count in the examined market raw milk that was 3.36x107 ± 1.62x107.Staphylococci aureus was detected in 32% (32/100) of the total examined samples.