Small Intestinal Bacterial Overgrowth (SIBO): A Review of Diagnostics and Therapeutics

Abstract

Introduction and purpose. Small intestinal bacterial overgrowth (SIBO) is defined as an abnormal presence of colon-type bacteria in the small intestine (≥10⁵ CFU/ml). This condition causes excessive gas, bloating, and potentially malabsorption or vitamin deficiencies. The aim of this review is to summarize the current knowledge regarding SIBO's clinical manifestation, diagnostics, and treatment.

A brief description of the state of knowledge. SIBO is associated with motor disorders, anatomical defects, and systemic diseases. Its symptoms are non-specific and overlap with irritable bowel syndrome. While jejunal aspiration with quantitative culture is the diagnostic gold standard, non-invasive breath tests measuring hydrogen, methane, and hydrogen sulfide are currently utilized to distinguish specific SIBO subtypes. Treatment relies on antibiotics for bacterial eradication, with rifaximin being the preferred antibiotic due to its efficacy and tolerability in patients. Such treatment is supplemented by short-term (4-6 weeks) dietary interventions, such as the low-FODMAP diet, to restore intestinal eubiosis by eliminating fermentable nutrients. Furthermore, probiotics have shown potential in supporting therapy as well as fecal microbiota transplantation, though scientific evidence remains limited.

Summary. Managing SIBO is a complex challenge requiring objective diagnosis and targeted antibiotic eradication. Crucially, preventing recurrence strictly depends on treating the underlying predisposing disease. While temporary dietary restrictions assist in restoring eubiosis, as well as the usage of probiotic and FMT the current quality of scientific evidence is insufficient.