A One Health Perspective on Bacillus Cereus in Animal-Origin Food Chains

The most common foodborne pathogen that have important role in the food chains of the animal origin is Bacillus cereus. Because numerous presumptive isolates of the Bacillus do not accurately represent true B. cereus, relying solely on culture-based identification can be misleading. The aim of this study was to make a clear assessment of its true prevalence via molecular confirmation, while also investigating the distribution of the hblA and blaZ genes among that verified isolates. These samples were recently obtained from workers, environmental sources, and poultry in the city of the Al-Qadisiyah, Iraq. To achieve this, a total of the 200 samples were initially cultivated by researchers on nutrient agar and Mannitol Egg Yolk Polymyxin (MYP). After this, we personally selected 40 presumptive isolates and amplified them using PCR targeting the 16S rRNA gene (594 bp) for the precise identification. The presence of the resistance and virulence-associated genes was then checked exclusively in the confirmed B. cereus isolates. We evaluated their phenotypic resistance to ampicillin using the disk diffusion method. Molecular confirmation ultimately verified that merely 15 (37.5%) of the 40 isolates initially recognized as presumptive Bacillus via phenotypic evaluation were truly B. cereus. Ampicillin resistance was observed in the all confirmed isolates that contain hblA and blaZ genes. With 100% of the all tested isolates confirmed, the rates of the confirmation peaked in the workers' hand swabs and washing water. A uniformly distributed presence was indicated because there was no difference across various sample sources according to the statistical analysis (P > 0.05). An overestimation of the B. cereus prevalence is the main cause of the limitations of the culture-based techniques, as demonstrated by these findings. From a public health perspective, the fact that the verified isolates were uniformly toxigenic and ampicillin-resistant is deeply concerning. The important need for the harmonized surveillance approaches that depending on one Health, specifically within poultry production systems, is highlighted by several observations such as this.