Bacteriological evaluation of Bacillus species isolated from food of animal origin

Document Type : Original Article


1 Bacteriology, Immunology and Mycology Department., Faculty of Veterinary Medicine, Benha University

2 Bacteriology Department, Animal Health Research Institute - Banha Branch, Agriculture Research Center (ARC), Egypt


Genus Bacillus is Gram-positive large bacterial group containing about 305 species; most of them cause serious diseases. The current study aimed to isolate Bacillus species from different food sources with investigation to species causing food poisoning and determine their in- vitro susceptibility and their virulence genes. The study was done on 100 samples of different food sources (raw milk (20), Kariesh cheese (10), low salt cheese (10), Ras cheese (Roomy)(10), Rice Kofta (17), Kobiba (17) and beef burger (16)) collected from different sources. The results declared that, the most isolated species were B. cereus (14/35%), B. mycoides (9/22.5%), B. thuringenesis (7/17.5%), B. alcalophilus (7/17.5%), B. subtilis (2/ 5%) and B. algicola (1/2.5%) from examined samples. Determination of susceptibility of the isolated B. cereus against different antibiotics, showed that all strains were completely resistant to Vancomycin (100%) followed by Amoxicillin (85.7%), intermediate sensitivity to Clindamycin (78.6%) and Doxycycline (64.3%), while they were highly susceptible to Gentamycin and Ciprofloxacin (85.7%) then Erythromycin (78.6%) and Norfloxacin (71.4%). The molecular examination of virulence genes (cytK, ces and pc-plc) in the virulent isolates (three isolates of B. cereus, two isolates of B. mycoides and two isolates of B. thuringenesis) existed presences of cytK and pc-plc genes in all examined isolates and absence of ces genes.This concluded that several Bacillus species may isolated from dairy and meat products and may have several virulence genes that cause food poisoning, so food hygiene is essential.


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