Targeted antibiotic and dietary approaches in managing small intestinal bacterial overgrowth across irritable bowel syndrome subtypes

INTRODUCTION: Irritable bowel syndrome (IBS) is a prevalent functional disorder, comprising constipation-predominant (IBS-C), diarrhea-predominant (IBS-D), and mixed (IBS-M) subtypes. Emerging research has shown that the pathophysiological influences of SIBO are significant in IBS, particularly in IBS-D. Variations in therapeutic responsiveness and diagnostic paradigms across IBS subtypes necessitate a tailored, subtype-specific management framework. METHODS: A review of identification strategies, SIBO subtype-specific prevalence, and treatment outcomes was supplemented through controlled randomized trials and observational studies. The treatment outcomes were evaluated in relation to SIBO and within the frameworks of rifaximin, neomycin, probiotics, and dietary modulation. RESULTS: The prevalence of SIBO is notably greater in IBS patients, particularly in those with IBS-D, with figures estimating ranges from 30 to 60% depending upon the diagnostic methods and cutoff thresholds. Though limited in its sensitivity and standardization, breath testing, particularly glucose hydrogen/methane tests, remains the most widely accessible diagnostic technique. Methane-predominant SIBO in IBS-C does respond better to rifaximin-neomycin combinations, but rifaximin provides strong symptom relief in IBS-D. Significant gaps persist, however, with the absence of longitudinal outcome measurements and standardization of IBS diagnostic criteria. In order to improve the care for IBS patients, the strategies targeting precision medicine with microbiota profiling and algorithm-driven personalized therapies must be accorded priority. CONCLUSIONS: SIBO is increasingly recognized as a potential contributor in a subset of patients with IBS, with rifaximin being most beneficial for IBS-D, particularly when utilized in addition to dietary measures. IBS-C and IBS-M require individualized, multimodal therapy, and future studies should direct efforts toward subtype-specific, precision medicine treatments for improved long-term outcomes.