LAUSR

Abstract Bacillus cereus is a major foodborne pathogen with the potential of causing emetic and diarrhoeal food poisoning. This study reports on the development of a sensitive and reliable method that involves direct DNA extraction from powdered milk and infant formula and a multiplex PCR for detection of four B. cereus toxin genes (nheA, hblD, cytK2 and cesB). Detection limits were 2 × 102 cfu g−1 for enterotoxin genes and 2 × 103 cfu g−1 for both the enterotoxin and emetic genes. Determination of B. cereus toxin genes in powdered dairy food samples revealed five toxigenic groups. Groups I to IV contained enterotoxin genes while group V, enterotoxin and emetic genes. The results indicate that the molecular method developed is a rapid and efficient diagnostic tool for direct detection and monitoring of B. cereus toxin genes in powdered milk and infant formula and possibly in other powdered foods.