Possible Crosstalk Between Small Intestinal Bacterial Over-growth (SIBO) and Atopic Manifestations - A Short Overview

Background: Small intestine bacterial overgrowth (SIBO) is an increasingly recognized condition influencing immune responses. It may be linked to atopic disorders such as bronchial asthma (BA), food allergies (FA), chronic spontaneous urticaria (CSU), and mast cell activation syndrome (MCAS). Objective: To systematically review the possible correlation between SIBO and presentation of atopic disorders. Methods: A comprehensive review of databases (PubMed, Embase, Web of Science and Google Scholar) was performed following PRISMA 2020 guidelines. Seven studies met the inclusion criteria. Results: Prevalence of SIBO was the highest in patients with BA (60-100%) and FA (50-87.5%), followed by MCAS (30.9%) and CSU (27.9%). The diagnosis of SIBO was based on lactulose or glucose breath-tests. SIBO exacerbated symptoms of atopic diseases and treating it in BA and MCAS improved the symptoms, contrary to CSU. Conclusion: Present evidence suggests correlation between SIBO and atopic manifestations. Bacterial overgrowth appears to trigger the Th2 immune response via mucosal pathway and low-grade endotoxemia. These result in increased synthesis of interleukins involved in allergic reactions (IL-4, IL-5, IL-13). Further studies are essential to confirm the clinical significance of this association. The “gut-allergy axis” may offer new therapeutic options and possibly improve the quality of life in atopic patients.