The hypotheses on the outbreak of the diarrheal type of food poisoning mediated by B. cereus need to be reviewed to some extent. It seems that, contrary to the prevailing opinion, the
ingestion of food highly contaminated with B. cereus spores and/or the significant growth of these microorganisms in the intestines is not prerequisite for the outbreak of the diarrheal type of food poisoning. It is rather the local growth and production of enterotoxins in the immediate vicinity of the human mucus layer or surface of the epithelial cells that causes this diarrheal form of the disease. The results of the latest studies concerning the effect of
indigenous microflora on the survival of B. cereus in the intestinal passage suggest that the intestinal microbiota of a healthy person seriously inhibits the growth of vegetative B. cereus cells and may constitute the last element of the human body's defence mecha-
nism against pathogens.