OCCURRENCE OF BACILLUS CEREUS IN SELECTED DRY FOOD PRODUCTS1,2

Abstract

One hundred seventy samples of dried food products in national distribution were examined for the incidence and level of contamination by Bacillus cereus. Twenty-five per cent of the samples yielded B. cereus at a level not exceeding 4000 per gram. Mannitol-egg yolk-polymyxin (MYP) agar was used as a presumptive test for the presence of B. cereus in the food samples. Various biochemical tests for the confirmation of suspicious colonies appearing on MYP agar were evaluated. A precipitin test employing spore precipitinogens was investigated as a confirmatory test for B. cereus. The possible role of B. cereus in outbreaks of foodborne disease in the United States is discussed.