Pathogenic Mechanisms of Bacterial Enteropathogens

Two important steps are involved in the pathogenesis of bacterial enteric pathogens. All the enteric pathogens, which enter the gastrointestinal tract through the mouth with food or water, colonize a certain part of the intestine. This important step is called colonization (4, 9) . For example, Vibrio cholerae and Vibrio parahaemolyticus colonize the mucosa of the upper jejunum, whereas Shigella colonizes the ileocaecum and colon. This event (colonization) is mediated by the production of specific surface antigens called "colonization factors" and specific receptors for the factors. The reason for the differences between the symptoms produced by V. cholerae O1 and V. parahaemolyticus, both of which colonize a similar region of the small intestine, is that they produce different toxins. Thus the second important step in the pathogenesis of bacterial enteric pathogens is the production of toxins and/or invasion.