Abstract
A total of one hundred and fifty (150) “awara” samples were collected from different vendors in various parts of Kaduna metropolis and assessed for the presence of Bacillus spp. Three species of Bacillus (Bacillus cereus, Bacillus subtilis, and Bacillus licheniformis) were isolated on Mannitol Egg-yolk polymyxin Agar plates, characterized and identified from the “awara” samples by conventional method (Biochemical test). The occurrence of Bacillus cereus, Bacillus subtilis and Bacillus Licheniformis were 51 (34%), 22 (14.7%) and 13 (8.7%). All the samples tested contained high number of Bacillus spp where Bacillus cereus had the highest number. Statistical analysis using P-Values indicated statistically significant difference (P=0.001) in Kawo and Tudun wada while there was no statistically significant difference in Unguwan dosa (P=0.341). Isolates were found to possess the hblD enterotoxin produced by Bacillus cereus. The enterotoxin producing Bacillus cereus isolates were found to be susceptible to Pefloxacin (10µg), Ciprofloxacin (10µg), Streptomycin (10µg), Septrin (30µg) and Erythromycin (10µg). Resistance was observed against Ampiclox (30µg) while Gentamycin, (10µg), Zinnacef (20µg), Amoxacillin (30µg) and Rocephin (25µg) were found to be less susceptible respectively. All the “awara” samples were highly contaminated with B. cereus probably because its spores were very difficult to be eliminated from food materials by heat treatment. However, any outbreak can be effectively treated using the antibiotics that showed susceptibility.
Highlights
Bacillus cereus is a Gram-positive, spore-forming microorganism capable of causing foodborne disease
All the Bacillus cereus isolated in the cause of this research revealed an irregular to round edge, flat, rough and dry bright pink colonies with zones of egg yolk precipitate on the selective agar (MYP) compared to other Bacillus spp identified
The occurrence of Bacillus cereus in this study showed that most of the samples examined were contaminated with Bacillus cereus having 51 (34%), occurrence followed by Bacillus subtilis having 22 (14.7%) and Bacillus licheniformis having 13 (8.7%) occurrence, which as a result, revealed a high incidence of Bacillus cereus
Summary
Bacillus cereus is a Gram-positive, spore-forming microorganism capable of causing foodborne disease. Able to cause the diarrheal syndrome, have been described: hemolysin BL (HBL), nonhemolytic enterotoxin (NHE) and cytotoxin K. HBL and NHE are othree-component proteins, whereas cytotoxin K is a single protein toxin. Symptoms caused by the latter toxin are more severe and may even involve necrosis. The onset of symptoms is within 6 to 24 h after consumption of the incriminated food. B. cereus food poisoning is underestimated probably because of the short duration of the illness (~24 h) [30]
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