Original Paper

Digestive Diseases and Sciences

, Volume 53, Issue 6, pp 1443-1454

First online:

A Systematic Review of Diagnostic Tests for Small Intestinal Bacterial Overgrowth

  • Reza KhoshiniAffiliated withDivision of Gastroenterology, Harbor UCLA Medical Center
  • , Sun-Chuan DaiAffiliated withGI Motility Program, Cedars-Sinai Medical Center
  • , Sheila LezcanoAffiliated withGI Motility Program, Cedars-Sinai Medical Center
  • , Mark PimentelAffiliated withGI Motility Program, Cedars-Sinai Medical Center Email author 

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Background A growing number of studies seem to suggest that small intestinal bacterial overgrowth (SIBO) is a common clinical problem. Although various techniques are available to make this diagnosis, tradition has accepted small bowel aspirate (>105 cfu/ml) as a gold standard. In this systematic review, the validity of culture and other diagnostic testing for SIBO is evaluated. Methods We performed a systematic review of the literature from 1966 to present using electronic databases (PubMed and OVID). Full paper review of those abstracts that fulfilled preset criteria was carried out to evaluate the validity of various tests in diagnosing SIBO. Finally, all papers were evaluated against published standards for studies on diagnostic testing. Results Seventy-one papers met the criteria for detailed review. Studies were very heterogeneous with regards to patient populations, test definitions, sample size, and methods in general. Small bowel colony counts appeared elevated in most gastrointestinal diseases compared to controls. The traditional definition of >105 cfu/ml was usually indicative of stagnant loop conditions. Although, numerous diagnostic tests were studied, not even culture papers met the quality standards described by Reid et al. Breath testing and other diagnostic testing suffered therefore from the lack of a gold standard against which to validate in addition to the poor quality. Conclusions There is no validated diagnostic test or gold standard for SIBO. In this context, the most practical method to evaluate SIBO in studies at this time would be a test, treat, and outcome technique.


Small intestinal bacterial overgrowth Diagnostic test Breath test Small bowel culture