483 Phenotype and Antibiotic Response in Patients With Elevated Baseline Hydrogen Breath Test Results: A Large Scale Database Analysis

Abstract

INTRODUCTION: Breath testing (BT) is a non-invasive method used for diagnosis of small intestinal bacterial overgrowth (SIBO). Elevated baseline hydrogen breath test results, defined as no excessive methane and elevated hydrogen production >20 part per million (ppm), is an uncommon but important pattern in breath testing. This result has been difficult to understand in clinical settings. Multiple interpretations are used including an abnormal result suggesting SIBO or attributing to poor compliance with the diet for the test. Large-scale studies are lacking to explore the clinical characteristics of these patients and potential response to treatment regimens. METHODS: We reviewed a database of 14,847 consecutive lactulose breath tests performed between November 2005 and October 2013 at a single institution. All subjects underwent a low fermentation diet on the day prior to the test and fasted for at least 8 hours overnight. Compliance to diet and fasting was confirmed prior to testing. Breath tests with an elevated baseline hydrogen result (>20 ppm) were identified. A retrospective chart review was performed to retrieve patient characteristics including age, gender, BMI, symptoms, and medications. Furthermore, the response to and type of antibiotic treatment was assessed. RESULTS: A cohort of 107 patients with elevated baseline hydrogen BT was identified. Basic demographics showed females comprising 72%, mean age 40.3 (std dev 19.3) and mean BMI = 24.2 kg/m2 (std dev 5.7). The most common symptoms experienced included abdominal pain (84%), bloating/distention (87%), fecal urgency (82%) and flatulence (80%) (Table 1). Regarding medications relevant to SIBO, patients used PPI (31%), chronic narcotics (21%), probiotics (5%) and antidiarrheals (10%). In patients who were treated with antibiotics after an elevated baseline hydrogen result (n = 22), 55% responded to antibiotics. Response rates in the rifaximin alone group (n = 11) and rifaximin plus neomycin group (n = 4) were 73% and 25% respectively (P < 0.01) CONCLUSION: In the largest cohort of patients with elevated baseline hydrogen breath tests analyzed to date, the most common gastrointestinal symptoms were abdominal bloating, pain, and urgency. Response to rifaximin alone appeared better than rifaximin/neomycin however small sample sizes were analyzed. An elevated baseline hydrogen breath test can occur despite full compliance with diet and fasting prior to the test. Further prospective controlled studies are needed to validate these findings