Comparative studies of Bacillus cereus strains isolated from various foods and food poisoning outbreaks.

Certain properties of 22 Bacillus cereus strains isolated from different foods and food poisoning episodes were investigated in order to evaluate possible différences between strains isolated from diarrhoeal and vomiting type food poisoning outbreaks. None of the strains isolated from vomiting type episodes produced acid from salicin and mannose, whereas 80 and 40 % of the strains from diarrhoeal type outbreaks were positive, respectively. No association between the antibiotic sensitivity pattern or the fatty acid composition and the source of a strain could be found, although some strains differed from the general pattern of B. cereus in some instances. No significant differences in the production of the skin factor between strains isolated from the two types of outbreaks were found either. The findings of this study support the observation that the food environment itself essentially affects the enterotoxin formation of B. cereus.