Fig. 1.

Schematic diagram showing the frequency of small intestinal bacterial overgrowth (SIBO) using quantitative jejunal aspirate culture, glucose and lactulose hydrogen breath tests (GHBT and LHBT, respectively) among patients with irritable bowel syndrome (IBS), gut defense mechanisms that prevent the development of SIBO, factors associated with SIBO among patients with IBS, and mechanisms of IBS symptom development. As shown in the figure, the frequency of SIBO in IBS patients using LHBT (early-peak criteria) is higher than that by using upper gut aspirate culture and GHBT (LHBT [45%]; upper gut aspirate culture [23%] and GHBT [26%]). Moreover, SIBO is more frequent in healthy controls using LHBT due to false positive test results (LHBT [21%], upper gut aspirate culture [1%] and GHBT [5%]).

GI, gastrointestinal; IBS-D, irritable bowel syndrome, diarrhea-predominan; PPI, proton pump inhibitor; CHO, carbohydrate.