Search

Mucosal surfaces of the gut are colonized by large numbers of heterogeneous bacteria that contribute to intestinal health and disease. In genetically susceptible individuals, a 'pathogenic community' may arise, whereby abnormal gut flora contributes to alterations in the mucosa and local immune system leading to gastrointestinal disease. These diseases include enteric infections, such as Clostridium difficile infection, small intestinal bacterial overgrowth, functional gastrointestinal disorders (including IBS), IBD and colorectal cancer. Prebiotics, probiotics and synbiotics (a combination of prebiotics and probiotics) have the capacity to reverse pathologic changes in gut flora and local immunity. Intestinal health and disease need to be thoroughly characterized to understand the interplay between the indigenous microbiota, the immune system and genetic host factors. This Review provides a broad overview of the importance of the intestinal microbiota in chronic disorders of the gut.

Travelers' diarrhea occurs when persons move from industrialized regions to developing countries with reduced hygiene. Bacterial enteropathogens from ingested food are the primary causes. Although it is possible to reduce the occurrence of illness by careful selection of food and beverages, travelers do not seem willing to restrict their diets. Diarrhea is associated with a disability of 24 hours per episode, interfering with travel plans and, of even greater concern, post-diarrhea irritable bowel syndrome (IBS) occurs in up to 10% of patients. The use of rifaximin, a poorly absorbed drug, is likely to become common as an attempt to prevent diarrhea and post-infectious IBS. All travelers to high-risk areas should take with them an effective antibacterial drug (rifaximin, fluoroquinolones, or azithromycin) for self-treatment of diarrhea occurring during travel. Additional work is needed to improve the hygienic conditions found in the developing world into which susceptible persons travel.