Prevalence of Bacillus cereus in milk and some milk products in Egypt

Elgushi, Ahmed Mohammed; Elbarbary, Hend Ahmed; Mohammed, Hamdi Abdelsamei; Elmasry, Dalia Mohammed Ali

doi:10.21608/bvmj.2023.228010.1699

Prevalence of Bacillus cereus in milk and some milk products in Egypt

Document Type : Original Article

Authors

¹ 1Food Hygiene and Control Department, Faculty of Veterinary Medicine, Benha University, 13736, Egypt. 2Biotechnology Department, Animal Health Research Institute, Agriculture Research Center, Dokki, Egypt.

² Food Hygiene and Control Department, Faculty of Veterinary Medicine, Benha University, 13736, Egypt.

³ Nanomaterials Research and Synthesis Unit , Animal Health Research Institute, Agriculture Research Center , Dokki , Egypt.

10.21608/bvmj.2023.228010.1699

Abstract

Bacillus cereus is a spore-forming bacterium that causes food spoilage and food poisoning. This study aimed to evaluate the prevalence of enterotoxigenic Bacillus cereus in 180 dairy samples across 3 cites (Tanta, El-Santa, and El-Mahalla El-Kubra) in El-Gharbia Governorate, Egypt, including raw milk, milk powder and Ras cheese. Samples were collected from December 2022 to April 2023 and analyzed using traditional isolation, biochemical identification with VITEK 2, and PCR targeting the nheA gene as a virulence factor for Bacillus cereus. Traditional isolation on selective media indicated a prevalence of 1.66%, 24.99% and 4.99% in raw milk, milk powder and Ras cheese, respectively. However, VITEK 2 only confirmed Bacillus cereus in milk powder isolates 24.99%. PCR detection of the nheA gene revealed Bacillus cereus in the examined samples was completely matching with traditional isolation. Overall, 10.5% of samples were positive for enterotoxigenic Bacillus cereus by PCR. Compared to PCR, traditional isolation showed 100% sensitivity and specificity, while VITEK 2 had 79% sensitivity and 100% specificity. Although biochemical methods like VITEK 2 enable rapid automated identification, PCR detection of virulence genes provides superior sensitivity for identifying enterotoxigenic Bacillus cereus of clinical significance from dairy samples. Traditional culture techniques remain essential for isolating target bacteria prior to PCR. This study provides insights into the prevalence of enterotoxigenic Bacillus cereus contamination in some Egyptian dairy products.

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