Irritable bowel syndrome and small intestinal bacterial overgrowth: Assessment with breath test

Abstract

Background: Irritable bowel syndrome (IBS) has been considered a functional disease, however evidences suggest organic abnormalities as disbiosis. The aim of this study was to evaluate bacterial overgrowth syndrome in IBS patients. Methods: Patients with IBS were submited to the expired H2 and CH4 breath test, with analyzes of exhaled air in fasting (zero minutes) and after the administration of 10g of lactulose, at times: 15, 30, 60, 90, 120, 150 and 180 minutes. The test was considered positive when the values of H2 or CH4 at 90 minutes were 20 ppm above baseline values. Results: Fourth-six patients were included, 23 (50%) had diarrheal subtype, 12 (26.1%) had constipated subtype and 11 (23.9%) had mixed subtype. All patients were submitted to lactulose breath test (LBT), with evaluation of expired H2 and CH4. The H2 test positivity was 15.2% and the CH4 test was 10.9%. In the diarrheal subgroup, the positivity of the H2 test was 13%, and at the CH4 test was 8.7%. Among the constipated patients, 16.7% were positive for H2 test, and none was positive for CH4 test. At the mixed subtype, the H2 test was positive for 18.2% and CH4 test for 27.3%. There was no significant correlation between the positivity of expired H2 test with the diarrheal subtype, and neither the expired CH4 test with the constipated subtype. Conclusion: LBT has not altered in patients with three forms of IBS. The optimization of diagnostic methods is necessary for a more accurate diagnosis.