Enteric bacterial toxins: Mechanisms of action and linkage to intestinal secretion

A wide range of bacteria have been implicated as potential etiologies of diarrheal disease. Many of these organisms have been reported to produce one or more toxins postulated as important in the pathogenesis of the diarrhea resulting from infection with the organism. The primary goal of this review is to critically assess the linkage between the mechanism of action of toxins produced by human enteric pathogens and the stimulation of intestinal secretion. To accomplish this goal, the range of criteria used to demonstrate pathogenicity of an enteric bacterial toxin and potential mechanisms stimulating net intestinal secretion are reviewed. A detailed description of each enteric toxin is presented, and revised criteria are proposed for classification of enteric bacterial toxins. Throughout this review, emphasis has been given to data derived from studies of toxins in potentially relevant models of disease, namely intestinal mucosa in vivo and/or intestinal epithelial cells in vitro.