الفهرس 
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Abstract
This work was carried out for isolation and identification of Bacillus cereus isolated form milk products, studying the sensitivity of B. cereus to antimicrobial agents and detection of plasmids in these isolates as B. cereus has public health hazard and cause economic losses in dairy industry.
The results are summarized in the following points:
1. Bacteriological examination was carried out to 130 samples of milk products (60 yogurt, 40 Ice cream, 15 processed cheese and (15 Ras cheese). On blood agar results were 43(71.66%) yogurt, 27(72.5%) ice cream, 9 (60%) processed cheese and 11(73.33%) Ras cheese. While, on PEMBA it was 25 (41.66%) yogurt, 26 (65%) ice cream, 5 (33.33%) processed cheese and 6 (40%) Ras cheese.
2. The biochemical reactions of the isolates from the two media were studied and the positive results shown by isolates form blood agar were 33 (76.74%) yogurt, (16 (55.17%) ice cream, 4 (44.44%) processed cheese and 5(45.45%) Ras cheese. while, those of isolates from PEMBA were 18 (72%) yogurt, (11 (42.31%) ice cream, 2 (40%) processed cheese and 3 (50%) Ras cheese.
3. Toxigenicity assays for 10 B. cereus isolates were studied and it was found that 6 isolates were able to produce hemolysin (60%) while, mouse lethal-toxin assay revealed killing of mice by 2 isolates
(20%).
4. Detection of plasmids was carried out to 15 isolates of B. cereus and it was found that all plasmids were identical (23 kbp).
5. In vitro sensitivity test revealed that gentamicine had the superior sensitivity (75%). Then chioramphenicol and ciprofloxacin (66.7% for each), 7 isolates showed sensitivity to norfioxacin (5 8.3%) while, 11 isolates were resistant to penicillin (9 1.7%).