Efficacy of Rifaximin, a Nonabsorbed Oral Antibiotic, in the Treatment of Small Intestinal Bacterial Overgrowth

Rifamixin is an orally administrated, nonabsorbed antibiotic whose utility in eradication of small intestinal bacterial overgrowth (SIBO) is currently being evaluated. The aim of this study was to investigate efficacy and safety of rifaximin in relieving symptoms and normalizing the glucose breath test (GBT) in patients with SIBO. Symptom score assessment, consisting of frequency and severity of bloating, gas, abdominal pain, and bowel movements and the GBT were performed before and after treatment with rifaximin 800mg/d for 4weeks. Twenty consecutive symptomatic patients (16 women and 4 men; mean age, 47.8years; range, 19 to 85years) who had a positive GBT were prospectively studied in an open-labeled fashion. Fourteen patients (70.0%) presented with diarrhea, 3 (15.0%) with bloating and gas, and 3 (15.0%) with constipation as the dominant symptom. Eleven patients were hydrogen producers, 8 exclusively methane, and 1 patient produced both gases by the GBT. Among patients with diarrhea, 12 of 14 (85.7%) reported improvement in symptom scores of more than 50%; 1 between 25% and 50%, 1 had no response after 4weeks of rifamixin. Among patients with bloating and gas or constipation as the main symptom: 2 of 6 (33.3%) had improvement between 50% and 75%; 3 (50%) had 25% to 50% improvement, and 1 (16.7%) had no response. Repeat GBT at the end of the 4weeks showed that 54.5% of hydrogen formers and 50.0% of methane producers were eradicated, and there was a significant reduction (P