Prevalence and Antimicrobial Resistance of Bacillus cereus in Milk and Dairy Products

Abstract

Objective: To investigate the prevalence of Bacillus cereus in milk and dairy products along with detection of its antibiotic sensitivity.

Design: Descriptive study.

Samples: One hundred and fifty samples of market milk, ultra high temperature milk packs (UHT), condensed milk, Milk powder, Damietta cheese, Kariesh cheese and Ras cheese.

Procedures: Samples were examined for isolation and identification of Bacillus spp. via direct and indirect isolation, molecular  examination and antimicrobial resistance. Further molecular examination was carried out in 46 isolates to detect hblA, hblC, hblD, nheA,  nheB and nheC genes

Results: The prevalence of B. cereus by direct isolation was 52%, 13.3 %, 10%, 8%,44%, 0 % and 16% in market milk,  ultra high temperature milk packs (UHT) , condensed milk , Milk powder, Damietta cheese, Kariesh cheese and Ras cheese, respectively,  whereas its prevalence by indirect isolation was 64%, 20%, 20%, 48%, 52%, 40% and 36% in market milk, ultra high temperature milk packs  (UHT) , condensed milk , Milk powder, Damietta cheese, Kariesh cheese and Ras cheese, respectively. B. cereus isolates were 100% resistant to colistin (CT), ampicillin (AM) and amoxicillin (AML). However, 83.01% were resistant to ampicillin-sulbactum (SAM), 67.9%  resistant to streptomycin (S), 45.2% resistant to spiramycin (SP), 35.8% resistant to lincomysin (MY), 22.6% resistant to tetracyclin (TE), and  5.6% resistant to erythromycin (E). A prevalence of 58.6% for hblA, hblC and hblD was recorded, while a prevalence of 86.9%, 93.4%  and 89.1% for nheA, nheB and nheC was recorded.

Conclusion and clinical relevance: This study provides data on prevalence,  contamination level and antibiotic sensitivity of B. cereus in milk and its products, suggesting a potential risk to health and the dairy industry.