Diagnosis and treatment of small intestinal bacterial overgrowth.

A huge number of bacteria are hosted in the gastrointestinal tract, following a gradient increasing towards the colon. Gastric acid secretion and intestinal clearance provide the qualitative and quantitative partitioning of intestinal bacteria; small intestinal bacteria overgrowth (SIBO) occurs when these barrier mechanisms fail. Diagnosis of SIBO is challenging due to the low specificity of symptoms, the frequent association with other diseases of the gastrointestinal tract and the absence of optimal objective diagnostic tests. The therapeutic approach to SIBO is oriented towards resolving predisposing conditions, and is supported by antibiotic treatment to restore the normal small intestinal microflora and by modifications of dietary habits for symptomatic relief. In the near future, metagenomics and metabolomics will help to overcome the uncertainties of SIBO diagnosis and the pitfalls of therapeutic management, allowing the design of a personalized strategy based on the direct insight into the small intestinal microbial community.