Small Intestinal Bacterial Overgrowth: Diagnosis and Treatment

Small intestinal bacterial overgrowth (SIBO) is a clinical condition characterized by a malabsorption syndrome due to an increase in microorganisms within the small intestine. The main mechanisms restricting bacterial colonization in the upper gut are the gastric acid barrier, mucosal and systemic immunity and intestinal clearance. When these mechanisms fail, bacterial overgrowth develops. Diarrhea, steatorrhea, chronic abdominal pain, bloating and flatulence are common symptoms and are similar to those observed in irritable bowel syndrome. Breath tests (glucose and/or lactulose breath tests) have been proposed as a sensitive and simple tool for the diagnosis of bacterial overgrowth, being non-invasive and inexpensive compared to the gold standard represented by the culture of intestinal aspirates. Antibiotic therapy is the cornerstone of SIBO treatment. Current SIBO treatment is based on empirical courses of broad-spectrum antibiotics since few controlled studies concerning the choice and duration of antibiotic therapy are available at present.