Bacillus Cereus isolation and load from raw cow milk sold in Markets of Haramaya District, eastern Ethiopia

Abstract

Abstract Background Bacillus cereus is a spore-forming bacterium that is widely distributed in the environment and can be detected in a variety of raw milk and milk products especially in vegetative form, which exposed directly in contact with the soil and produces toxins which caused food borne illness and considered as a significant public health hazard. A cross-sectional study was carried out to determine the prevalence and load of Bacillus cereus vegetative cells in raw bulk milk sold in market places at Bate, Haramaya and Aweday Towns, Eastern Ethiopia as well as to assess the in-vitro antimicrobial susceptibility of isolates. A total of 103 raw milk samples were collected and examined for the presence of Bacillus cereus by using Bacillus cereus selective agar media. The isolated presumptive colonies were further analyzed using standard microbiological methods to confirm the presence of Bacillus cereus. Spreading plate method was employed to count the bacteria from milk samples based on 10 fold serial dilutions. For antimicrobial susceptibility test, the disc diffusion test was employed using commercially available 10 antimicrobial discs. Results The overall prevalence’s of Bacillus cereus in raw milk samples was 38.8%. Milk collected from Aweday market showed higher occurrence (46.9%) than from Bate (40%) and Haramaya town (31.7%). Analysis of bacterial count showed that, 60% of Bacillus cereus positive milk samples were with bacterial load above recommended limit (>105CFU/ml) for human consumption. However, there was no statistically significant difference (p > 0.05) on the occurrence of Bacillus cereus and bacterial load among different areas. Based on disc diffusion test, B. cereus isolates showed high resistance to Penicillin (100%), Ampicillin (100%), Amoxicillin (80%) and Cefoxitin (80%). Conclusion The study indicated that milk samples from market areas were highly contaminated with Bacillus cereus, with potential risk for human consumption. This suggests the need for effective hygienic measures to be introduced during milk production and distribution to avoid public health hazards.

Keywords

• Bacillus cereus
• Bacterial load
• Drug susceptibility
• Raw bulk milk