Pathogenesis of gastrointestinal infections.

The normal gastrointestinal tract is constantly "infected" by a large and varied microbial population. This normal flora plays a significant role in establishing and maintaining the normal state of the digestive tract. Although the digestive ecosystem thus constituted has a high degree of stability, some microbes have evolved virulence factors or characteristics that allow them to gain a foot-hold in the tract. Given the variety of virulence factors found in different organisms, gastrointestinal infectious diseases are characterized by a broad spectrum of patterns which differ with respect to the relationship between microbe and host, i.e., the degree of tissue penetration by the organism. Genetic analysis of virulence factors promises to deepen our understanding of the pathogenesis of these diseases and to lead ultimately to effective means of prevention.