Bacterial Infections of the Small and Large Intestine

Diarrhea caused by enteric infections is a major cause of morbidity and mortality worldwide. This chapter highlights the mechanisms of diarrhea associated with bacterial agents. Several bacterial pathogens can cause secretory diarrhea such as Vibrio cholerae and enterotoxigenic Escherichia coli. Other bacteria induce inflammatory diarrhea such as Clostridium difficile, Shigella, and selected strains of pathogenic E. coli, while some induce osmotic diarrhea by causing extensive enterocyte damage by cytopathic mechanisms, such as enteroaggregative E. coli. The underlying mechanisms of infectious diarrhea include alterations in ion transport as well as cytotoxic effects. These are induced by bacterial cells and/or by their virulence factors. Diarrheal mechanisms may be indirectly caused by inflammation or by altered regulatory processes involving hormones and neurotransmitters. This chapter also provides a review of the current treatment of acute infectious diarrhea by bacterial agents.