Molecular characterization of bacillus cereus isolated from milk and milk products

Abstract EN

In this study, one hundred and fifty milk and milk products samples collected from local markets in Kafrelsheikh Governorate were examined for the presence of B.

cereus, occurence of enterotoxins genes and sensitivity of B.

cereus isolates to Antibacterial agents.

The selective bacteriological isolation , colony morphology on Mannitol- Egg Yolk -Polymyxin (MYP) agar, , microscopical examination and biochemical identification revealed that a total of 49 (32.7 %) B.

cereus isolates were recovered, 5 (20%), 3 (12%), 13 (52%) 7 (28%), 9(36%) and 12 (48%) from raw milk, heat-treated milk, hard cheese, processed cheese, yogurt and dry milk respectively.

Screening of 30 identified B.

cereus strains by PCR method revealed that the rate of detection of hblC and nheA genes between the tested isolates was 22 (73.3%) and 27 (90%)respectively, while cyt K gene was not detected in any isolate.

In vitro sensitivity of the isolated bacteria to various antimicrobial agents revealed that Ciprofloxacin had the superior sensitivity (100%), then Chloramphenicol and Erythromycin (93.9 and 91.8 respectively), followed by Streptomycin and Clindamycin (83.7 and 81.6 respectively).

All isolates were resistant to Penicillin followed by Sulphamethoxazole-Trimethoprim (95.9), then Amoxycillin-Clavulonic acid (93.9).