Usage of Rifaximin for the Treatment of Hydrogen Positive Small Intestinal Bacterial Overgrowth

Abstract

Introduction: Small intestinal bacterial overgrowth (SIBO) is challenging to treat and diagnose and is associated with diagnosis of Irritable Bowel Syndrome (IBS). Although no FDA approved medications exist for treatment of SIBO, rifaximin has recently been FDA approved for the treatment of diarrheapredominant IBS, and has been recommended for treatment of patients with specifically methane positive SIBO breath tests. The aim of this study was to evaluate patient symptom response to rifaximin for SIBO based on breath test results. Methods: All patients undergoing breath testing to evaluate for SIBO at our tertiary-care motility center from 9/2012 to 3/2016 were included. Patients were defined as having a positive glucose or fructose (if diabetic) breath test for SIBO if there was an increase of ≥ 20 ppm of hydrogen and/or ≥ 10ppm of methane by 90 minutes (Rezaie et al; DDW 2016 Presentation#450).Patient demographic and symptom data, antibiotic treatment regimens, symptomatic response to therapy, and repeat treatments were recorded. IRB approval was obtained. Results: A total of 53 of 443 patients had positive breath testing for SIBO during the study period. Of these, 79.2% (42/53) were women, mean age 58 years (Range 16-86 years; SD 16.7). The most common symptoms for performing breath testing were abdominal bloating (60.4%), diarrhea (47.2%), excessive flatulence (30.2%), abdominal pain (24.5%), nausea (22.6%), and constipation (20.8%). At the time of the retrospective review, 42/53 (79.2%) had received antibiotic therapy. Therapeutic results were available in 28/42 (66.7%) (19 predominantly hydrogen positive; 4 methane positive; 5 both). Rifaximin was the most commonly prescribed antibiotic (78.4%). Response rates to rifaximin were 47.4% for hydrogen positivity alone (38.5% 1st line; 66.7% 2nd line); and 80% for both hydrogen and methane positivity (75% 1st line; 100% 2nd line). No patients with methane positivity alone were effectively treated with rifaximin. Conclusion: Rifaximin was the most commonly prescribed antibiotic regimen for SIBO therapy. Patients with hydrogen or hydrogen and methane positive breath tests responded better to rifaximin than those with methane positivity alone. Hydrogen positive SIBO rifaximin response rates were similar to prior TARGET 3 Study data of 36% rifaximin response in diarrhea predominant IBS, suggesting overlap of these conditions. Future prospective studies using rifaximin in a larger cohort may be warranted to validate our findings.