الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Milk and dairy products harbor several pathogens that have public health hazards. The outbreaks of diseases attributed to consumption of raw milk or dairy products manufactured from unpasteurized milk. This study included 125 samples (raw market milk, bulk tank milk, Kariesh cheese, white soft cheese, and small scale ice cream, 25 each). All samples were collected randomly from markets, shops, homes, and farms in Mansoura city, Dakahlia, Egypt. In this study E. coli and Salmonella were isolated followed by biochemical reaction, molecular identification, antimicrobial sensitivity test, and inactivation using D-Trp. Also, we determined the prevalence of S. aureus in the previous mentioned samples. During isolation of some food poisoning pathogens as E. coli ,Salmonella and S. aureus, several bacterial pathogens had also been isolated as Shigella, Citrobacter, Proteus, Providence, Enterobacter, Serratia, Klebsiella and Pseudomans. The prevalence of Salmonella in raw market milk, bulk tank milk, Kariesh cheese, white soft cheese, and ice cream was 0%, 8%, 8%, 0 and 0%, respectively. All Salmonella isolates were confirmed by biochemical tests, serological analysis and PCR. Antimicrobial susceptibility test showed that all isolates were resistant to streptomycin and erythromycin. About 77.8% of isolates were resistant to nalidixic acid. PCR showed that 3 strains S. Typhimurium and 2 strains S. Enteritidis harbored all examined 3 genes. S.Virochow and S. Larochelle harbored invA and stn genes.We used sorbitol macConkey agar media supplemented with cefixime and potassium tellurite for isolation of E. coli. The prevalence of E. coli in raw market milk, bulk tank milk, Kariesh cheese, white soft cheese, and ice cream was 44%, 12%, 48%, 4 and 0%, respectively. We also used PCR for determination of some virulent genes as eaeA, stx1, stx2 and rfbE genes. Our results illustrated the priority of isolates for stx1 than stx2 in all STEC populations. where 20 isolates harbored both stx1 and stx2 genes, 26 harbored only stx2 gene and 30 isolates harbored stx1 gene. Conclusion: Raw un heated milk is unfit for human consumption and D-Trp can be used as a novel tool for food preservation.