Double-blind, Placebo-controlled Antibiotic Treatment Study of Small Intestinal Bacterial Overgrowth in Children With Chronic Abdominal Pain

Background and Objectives: Chronic abdominal pain (CAP) in children may be a precursor to irritable bowel syndrome (IBS) in adults. The prevalence of abnormal lactulose breath tests (LBT) suggesting small intestinal bacterial overgrowth (SIBO) has been reported as 91% in children with CAP and 35% in healthy controls. In addition, patients with IBS with SIBO who responded to nonabsorbable antibiotic treatment with normalization of LBT reported 75% global improvement in symptoms. The aim of the study was to test whether treatment with a nonabsorbable antibiotic may reduce symptoms in children with CAP. Methods: Seventy-five children ages 8 to 18 years with CAP based on Rome II criteria were enrolled. Subjects underwent baseline LBT and completed symptom-based questionnaires. They were then randomized in a 2:1, double-blind fashion to receive a 10-day course of 550mg of rifaximin or placebo 3 times per day (t.i.d.). LBT and questionnaires were repeated 2 weeks after treatment. Results: Forty-nine children received rifaximin and 26 received placebo. There were no differences in demographics between groups. Ninety-four percent who received rifaximin and 92% who received placebo had abnormal baseline LBT, suggesting SIBO (not significant [NS]). There was no significant difference in symptom improvement between groups; however, only 20% of children treated with rifaximin achieved a normalized repeat LBT, demonstrating successful treatment of SIBO. Conclusions: Similar to adults with IBS, the prevalence of abnormal LBT suggesting SIBO in children with CAP is high; however, treatment with 10 days of rifaximin has low efficacy in normalizing LBT in this group. Additional studies are needed to determine whether a treatment approach with higher efficacy would lead to improvement in children with CAP.