The occurrence ofBacillus cereusin fast foods

The rate and the level of contamination by Bacillus cereus in various fast foods were investigated. The strains isolated were differentiated by DNA digestion with restriction enzymes and pulsed-field gel electrophoresis (PFGE). A total of 90 single servings of foods were purchased in 16 restaurants, cafeterias and buffets in Naples (Italy). Ten samples (11.1%) resulted in contamination by B. cereus. The contamination levels ranged from 103 to 105 cfu g-1. The most contaminated foods were the fish dishes (21.4%), with counts ranging between 104 and 105 cfu g-1. Such rate of contamination is noticeably lower than those reported in other countries. The genomic typing obtained by the PFGE of the restriction digests showed the existence of a high polymorphism also in the B. cereus strains isolated from different ready-to-eat foods purchased together in the same restaurant.