Development of a fluorescent immunodot assay for Bacillus cereus enterotoxin

A fluorescent immunodot assay has been developed for rapid, specific detection of B. cereus enterotoxin. None of the other Bacillus species tested showed cross-reactivity in the assay with antiserum to purified B. cereus enterotoxin. The assay can detect greater than or equal to 50 ng of purified enterotoxin. Using this assay system, enterotoxin was found to be produced by 25 of 25 foodborne disease-related isolates and 22 of 25 isolates not related to foodborne disease (isolates from routine surveillance foods). Because of the apparent widespread ability of isolates to produce enterotoxin the assay may have potential as a rapid identification procedure for B. cereus. The substrate gel system described may have wider application in other immunoassay systems using a membrane solid phase.