Hydrogen Breath Test an Instrument to Predict Rifaximin-Response in Irritable Bowel Syndrome Predominant Diarrhea

The purpose of this study is to learn more about how to improve treatment of patients with diarrhea predominant Irritable Bowel Syndrome (IBS-D) symptoms.Included patients will be requested to answer online surveys and will undergo treatment with rifaximin. Hydrogen breath testing and biologic samples collection will also be completed during the study.

The study aims to determine whether hydrogen breath testing can be used to identify patients with IBS-D who are more likely to respond to rifaximin. Participating patients will complete a one week screening period when brief daily survey will be answered. Eligible patients will proceed with the treatment phase of the study, when patients will receive a 14 day course of rifaximin. All included patients will complete glucose and lactulose hydrogen breath tests before and after rifaximin treatment. Biological samples (e.g. blood, stool) will be collected at pre-determined time points and patients will answer daily brief survey for the duration of the study. It is anticipated that 210 patients will be screened to reach a goal of enrolling 175 patients for the treatment phase of the study.