A new rapid and sensitive detection method for cereulide-producing Bacillus cereus using a cycleave real-time PCR

To develop a rapid and sensitive detection method for cereulide-producing Bacillus cereus using a real-time PCR based on the sequence of the cereulide synthesis gene.

A total of 56 cereulide-producing B. cereus and 15 cereulide-negative strains were tested. We designed specific primers and probes for the detection of cereulide-producing B. cereus. The new cycleave real-time PCR assay gave positive detections for all of 56 cereulide-producing B. cereus strains, whereas all other strains including 10 systemic infectious disease strains were negative. No cross-reaction was observed and the internal control showed positive for all samples.

The performance of the assay was highly reproducible and specific for cereulide-producing B. cereus. The positive detection was obtained within only 2 h for cereulide-producing strains. The detection limit of this assay was evaluated as 10(4) CFU g(-1) food sample. The assay also confirmed that strains from systemic infectious cases were cereulide-negative.

This assay is applicable for contaminated foods as well as specimens from infectious disease cases. We recommend this assay for routine examination of suspected B. cereus food poisonings.