Microbes and microbial toxins: paradigms for microbial-mucosal interactions. VII. Enteropathogenic Escherichia coli: physiological alterations from an extracellular position.

Enteropathogenic Escherichia coli (EPEC) is primarily associated with infantile diarrhea in developing countries. This intriguing pathogen exerts numerous physiological effects on its host target tissue, the intestinal epithelium, all from an extracellular location. Expression of a type III secretory apparatus allows this organism to transfer bacterial effector molecules directly into host cells. As a result of EPEC attachment to and/or translocation of proteins into intestinal epithelial cells, many signaling cascades are activated. Ultimately, host functions are perturbed, including alteration of ion transport, disruption of the tight junction barrier, and activation of the inflammatory response.