Lactulose and Glucose Breath Tests as Predictors of Clinical Benefit From Rifaximin in Irritable Bowel Syndrome

The Irritable Bowel Syndrome (IBS) is a frequent disease, affecting between 10 and 20% of general population. Several pathophysiologic mechanisms have been described in IBS, among them the role of intestinal microbiota and small intestinal bacterial overgrowth (SIBO) have received special attention. SIBO has an adequate response to antibiotic treatment, unfortunately it didn\'t have an adequate diagnostic test: The classic gold standard -jejunal aspirate culture- has been criticized due to lack of standardization; the breath tests are simpler and widely available, but they have also been criticized due to inadequate diagnostic accuracy for SIBO. For this reason seems important to evaluate the performance of breath tests in terms of predicting clinical benefit of antibiotic therapy in IBS patients, rather than predicting a positive culture and SIBO. The objectives of this study are: 1. Determine which breath test (lactulose or glucose) predicts better a potential clinical benefit of antibiotic treatment (Rifaximin) in IBS patients. 2. Determine which of the multiples diagnostic criteria described for the lactulose breath test predicts better a potential clinical benefit Rifaximin in IBS patients.