Microbial Toxins in Foods: The Importance of Escherichia coli, a Versatile Enemy [Chapt. 4]

When speaking of food microbiology, analysts and hygiene professionals are accustomed to starting their discussions with a relatively less number of food pathogen bacteria, in spite of the great variety of microbiological risks in the food and beverage sector. A few micro-organisms are well known with reference to the possibility of showing diversified strains. In other words, one specific micro-organism can spread into the environment and in selected ‘culture media’ like foods with the possible ‘permutation’ of the original strain in several sub-strains with different properties and features. This is the situation of Escherichia coli, the most important micro-organism in the group of so-called ‘Coliform’ bacteria. E. coli is a typical commensal of the intestinal tract of animals and humans. For its abundant presence in the colonic microflora, it is used as one of the most important indicators of faecal contamination in food and water. However, some subsets within this species have acquired specific virulence genes. Enteric strains have been divided into different pathotypes, depending on virulence factors and pathogenic features. In the present chapter, various E. coli pathotypes are described; particular relevance is given to toxin-producing strains. Additionally, this work intends to provide useful information about related toxins, their known chemical properties and the most used analytical methods in the food sector.