Purpose: The study aim was to decrease the turn-around time for enterotoxin detection in food matrices.
Methods: Food products obtained locally included dehydrated potato flakes, rice, pancake batter, gravy mix, protein powder and a dietary supplement as well as liquid milk and canned soup. Food portions were inoculated with Butterfield’s phosphate-buffered dilution water as the matrix control or one of five bacterial strains representative of either inclusivity or exclusivity test strains. Testing was performed on inoculated food portions following 5-h and 24-h incubation periods. An end-point multiplex PCR was used as a screen for four enterotoxin gene targets to include the emetic toxin gene and three diarrheal toxins, Hbl, Nhe and Cytk. Commercially available ELISA and LFD kits were used to determine the presence/absence of Nhe and Hbl. Finally, a quantitative analysis using mass spectrometry was performed for the detection of the emetic toxin.
Results: Inclusivity strains included three B. cereus strains that were all positive for Nhe, two were also positive for Hbl, one was positive for CytK, and one was positive for the emetic toxin gene. The PCR results of several DNA food product extracts revealed natural B. cereus contamination which was validated with plate enumeration, additional PCR testing and serological testing.
Significance: Definitive results were available after the five hour pre-enrichment for the emetic toxin testing in five food products and for the diarrheal enterotoxins for six of the food products demonstrating the availability of rapid turn-around times when compared to traditional methods. Definitive results were available for all food matrices following 24-h incubation.