Abstract
B. cereus is an opportunistic foodborne pathogen that is found in most of the cases to be responsible for food-borne outbreaks. This study aimed to detect and quantify B. cereus in dairy desserts that locally manufactured and sold in different localities in Qena city, also to take an image about the role that is may be played by these products in causing foodborne illness by detection of B. cereus in diarrheal samples collected from the same regions from which the food samples are obtained. A total of 120 samples of ice-cream, mahallbia, rice and milk and diarrhea (30 samples each) were examined for presence of B. cereus. The results obtained in this study revealed detection of B. cereus in 55.6 and 40% of dairy dessert and diarrhea samples, respectively. B. cereus could be counted in 30, 60 and 76.7% of ice-cream, mahallbia and rice and milk samples with mean values of 3.5× 104±1.5× 104, 6.3×105±1.9×105 and 1.4×107±6.6× 106 CFU/g, respectively. The possibility of involvement of theses dairy dessert samples in food poisoning cases was reinforced especially after detection the virulence genes of B. cereus isolates. It was found that 80, 44 and 24% of B. cereus isolates recovered from food samples harbored nhe, hbl and cytK genes, receptively including 55.6, 33.3 and 0% for ice-cream isolates; 83.3, 50 and 44.4% for mahallbia isolates and 86.9, 43.5 and 17.4% for rice and milk isolates. While for diarrhea samples, 75% of B. cereus isolates obtained from diarrhea samples carried nhe and cytK, respectively and 50% were found to be positive for hbl gene. Neither of the isolates that obtained from dairy dessert nor those obtained from diarrhea samples was positive for presence of ces gene.

Key words: B. cereus, Dairy desserts, Diarrhea and virulence genes