Introduction and study aim: IBS is the most common functional disorder of gastrointestinal (GI) tract. It is shown that intestinal microbiota plays an important role in the pathogenesis of Irritable Bowel Syndrome (IBS). Recent studies have been shown that probiotics could be effective in the improvement of IBS symptoms by changing gut normal microflora. In this study we investigated the probiotics' efficacy in prevention of small intestinal bacterial overgrowth (SIBO) recurrence among patients with IBS.
Patients and Methods: In a double blind clinical trial, patients with IBS and SIBO who were diagnosed based on positive Hydrogen breath test, initially received antibiotics for a period of 10 days and then randomly divided into 2 groups (Mutaflor probiotic and placebo) after confirmation of negative Hydrogen breath test. After 3 months treatment, breath tests were repeated and frequency of SIBO recurrence was compared between 2 groups.
Results: Among 172 patients with IBS and SIBO, 159 cases included  the study and after antibiotic treatment and negative breath tests, eventually 156 patients were analyzed. Both groups had similar demographic characters such as age, sex, IBS type and PPI consumption. Frequency of SIBO recurrence were significantly lower in the probiotic group than the placebo group (P=0.033). Frequency rate of constipation and mixed type of IBS were almost similar in both groups (P>0.05) and only there was a significant difference in SIBO frequency between 2 groups as diarrhea dominant IBS (P<0.05).
Conclusion: Our study showed that Mutaflor probiotic has beneficial effects on reduction of SIBO recurrence among IBS patients and could be successfully used for treatment of these patients.