The use of liquid chromatography coupled to mass spectrometry as a necessary tool for the assessment of cereulide in food
(2012)
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LaurenceDELBRASSINNE-AssessmentofcereulidebyLC-MS²-electronicthesis.pdf
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- (en) Certain B. cereus strains are able to produce an emetic toxin named cereulide which is at the origin of numerous foodborne outbreaks with even fatal outcomes. This stressed the importance of setting up rapid and reliable quantification methods for cereulide in food products. An optimized LC-MS² method was developed in the first part of this thesis and an in-house validation was performed according to the Commission Decision 2002/657/EC. The method was compared with other concurrent methods in terms of specificity, sensitivity and time consumption. It guaranteed low detection limits in rice (LOD of 0.5 ng/g) with a good repeatability and reproducibility. The robustness of the method was tested in other food matrices coming from industry (red beans, chili con carne, and spices) or from foodborne intoxications (i.e. white and fried rice, and bean soups) in which cereulide was detected at various levels (from 1.5 ng/g up to 13 µg/g). Besides, the actual concentration of cereulide was quantified in the pasta leftovers of a recent Belgian lethal case due to B. cereus and it helped to explicitly incriminate cereulide as the most probable cause of the death. The study of critical conditions (temperature and time of storage, type of strain) influencing cereulide production revealed that the correlation between toxin production and bacterial counts is more complex than proportional. The actual role of cereulide for its bacterial producer was also assessed. The emetic toxin displays a fungistatic activity against nine fungal species (Alternaria alternata, Botrytis cinerea, Cladosporium cucumerinum, Magnaporthe grisea, Monographella nivalis, Mortierella isabellina, Sclerotinia minor, Stemphylium vesicarium and Verticillium dahliae). Finally, the presence and concentrations of cereulide in rice dishes were assessed in Asian restaurants of Brussels and Wallonia. The prevalence of cereulide (7.4 % of the dishes analysed on the day of consumption contained cereulide) was higher than previously studied for the cereulide-producing strains and encourages to further characterize the risk of B. cereus emetic food poisoning.
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Delbrassinne, L. (2012). The use of liquid chromatography coupled to mass spectrometry as a necessary tool for the assessment of cereulide in food. https://hdl.handle.net/2078.5/160511