1. The definition of small intestinal bacterial overgrowth (SIBO) as a clinical entity lacks precision and consistency; it is a term generally applied to a clinical disorder where symptoms, clinical signs, and/or laboratory abnormalities are attributed to changes in the numbers of bacteria or in the composition of the bacterial population in the small intestine.
2. Symptoms traditionally linked to SIBO include bloating, diarrhea and abdominal pain/discomfort. Steatorrhea may be seen in more severe cases.
3. There is insufficient evidence to support the use of inflammatory markers, such as fecal calprotectin to detect SIBO.
4. Laboratory findings can include elevated folate and, less commonly, vitamin B-12 deficiency, or other nutritional deficiencies.
5. A major impediment to our ability to accurately define SIBO is our limited understanding of normal small intestinal microbial populations — progress in sampling technology and techniques to enumerate bacterial populations and their metabolic products should provide much needed clarity.
6. Controversy remains concerning the role of SIBO in the pathogenesis of common functional symptoms, such as those regarded as components of irritable bowel syndrome.
7. Management should focus on the identification and correction (where possible) of underlying causes, correction of nutritional deficiencies, and the administration of antibiotics. This is especially important for patients with significant maldigestion and malabsorption.
8. Although irritable bowel syndrome has been shown to respond to therapy with a poorly absorbed antibiotic, the role of SIBO or its eradication in the genesis of this response warrants further confirmation in randomized controlled trials.
9. There is a limited database to guide the clinician in developing antibiotic strategies for SIBO, in any context. Therapy remains, for the most part, empiric but must be ever mindful of the potential risks of long-term broad-spectrum antibiotic therapy.
