Small bowel bacterial overgrowth in adults: a potential contributor to intestinal failure.

Small bowel bacterial overgrowth (SBBO), in which colon-derived bacteria colonize the upper small bowel, is found in a wide variety of adult diseases associated with intestinal failure and dysfunction, including short bowel syndrome and other conditions following massive bowel resection, dysmotility disorders, and inflammatory bowel disease. SBBO also appears to be relatively common in the elderly, in whom it often goes unrecognized. SBBO is an important cause of malabsorption and thus may contribute to diarrhea and malnutrition. Elevated upper small intestinal aspirate colony counts remain the gold standard diagnostic test; a variety of noninvasive tests that detect elevated levels of breath hydrogen produced by bacterial fermentation of oral carbohydrate loads are also performed for diagnosis. Physicians commonly prescribe a variety of oral antibiotic regimens for documented or presumed SBBO. Additional research is needed to define the epidemiology, optimal diagnostic test(s), and therapeutic regimens for this condition.