Longterm outcome of acute severe ulcerative colitis in the rescue therapy era: a multicentre cohort study

Background: Small intestinal bacterial overgrowth (SIBO) has been reported with varying prevalence, de- pending upon the criteria used for diagnosis. Lactulose and glucose breath tests are the most used in clinical settings. Early rises of hydrogen excretion during a lactose breath test suggest SIBO, but the find- ing could result from accelerated mouth-to-caecum transit time. Aims: Defining the prevalence of early hydrogen peaks during lactose breath tests and assessing the proportion of patients affected by SIBO. Methods: An early ( ≤60 ) hydrogen excretion peak was observed in 120/663 patients with positive lac- tose hydrogen breath test. Eighty-one of them underwent a 50 g-9sample-glucose hydrogen breath test to diagnose SIBO. Results: The glucose breath test proved positive in 11/81 (13.6%) patients. The positivity rate was 18.2% (2/11) in those with the first peak detected at 30 and 12.8% (9/70) in those with the peak occurring at 60 . Conclusions: Early hydrogen excretion peaks are rarely associated with SIBO. The low positive predictive value indicates that the finding does not help identifying patients at high risk for this condition. Indi- rectly, the present data support the opinion that the prevalence of SIBO diagnosed by standard lactulose breath tests is much lower than reported, and the reliability of the test is low.