Objectives: Small intestinal bacterial overgrowth (SIBO) is challenging to treat and diagnose and is associated with diagnosisof irritable bowel syndrome (IBS). Although no FDA-approved medications exist for treatment of SIBO, rifaximin has recentlyreceived approval to treat diarrhea-predominant IBS and patients with methane-positive SIBO breath tests. The aim of thisstudy is to evaluate patient response to rifaximin for SIBO based on breath test results. Materials and methods: All patientsunderwent breath testing to evaluate for SIBO during a 42-month period. Patients were defined as having a positive glucosebreath test for SIBO based on an increase of ≥ 20 ppm of hydrogen and/or ≥ 10 ppm of methane 90 minutes after ingestingglucose. Patient demographic and symptom data, antibiotic treatment regimens, symptomatic response to therapy, and repeattreatments were recorded. Institutional...