Campylobacter species are believed to cause more cases of food poisoning than any othermicroorganism. Cronobacter sakazakii is a newly emerging pathogen; our understanding of this bacterium is increasing all the time.Interest in Bacillus species has been increasing in recent years; different species are potential sources of food poisoning, and there is now greater appreciation of their role in food spoilage and deterioration in food quality.Understanding of the role of yeasts and moulds in product shelf life is poorly understood, but work at Campden BRI has shown that problems with them need to be tackled rather differently to those involving bacteria.Toxicity due to fungal contamination is a complex issue, with different microorganisms causing problems in different parts of the world.