Diagnosis of small intestinal bacterial overgrowth in the clinical practice

Gut microbiota plays several beneficial effects on the human host. Its qualitative and/or quantitative unbalance may facilitate the occurrence of small intestinal bacterial overgrowth (SIBO).

To review the available data in order to propose a practical approach to SIBO diagnosis in the clinical setting.

Full papers from 1990 to present available on the Pubmed database concerning the topic of SIBO diagnosis were critically reviewed.

SIBO is common in the presence of one or more predisposing conditions. The clinical picture of SIBO patients is extremely variable, depending of underlying disorders, and both patients and microbiota characteristics. SIBO could be asymptomatic, or leading to aspecific gastrointestinal IBS-like symptoms. In worst cases it may configure a real malabsorption syndrome. Culture of intestinal aspirates remains at present the gold standard for SIBO diagnosis. However a lot of limitations including high costs and invasivity prevent from using this test in the clinical practice. Hydrogen lactulose and especially glucose breath tests are at present the most utilized to reach SIBO diagnosis in the clinical setting, due to their low costs, non invasivity, sufficient accuracy and reproducibility.

SIBO should be suspected in the presence of IBS-like symptoms and/or malabsorption syndrome occurring in the presence of disorders predisposing to SIBO development. The most common diagnostic tool is represented at present by hydrogen breath tests.