Small intestinal bacterial overgrowth in irritable bowel syndrome: frequency and its association with socio-demographic and clinical factors

Background: Irritable bowel syndrome (IBS) is a chronic functional relapsing GIT disorder characterized by abdominal pain in association with altered stool form or stool frequency in the absence of any other disease. Small intestinal bacterial overgrowth (SIBO) has been increasingly linked to IBS, particularly its diarrhea-predominant subtype (IBS-D). This study aimed to determine the frequency of SIBO in IBS patients and explore its association with socio-demographic and clinical factors. Methods: This observational cross-sectional study was conducted in the department of gastroenterology, Dhaka Medical College Hospital (DMCH), Dhaka, Bangladesh from September 2018 to August 2019. In this study, we included a total of 104 IBS patients who attended the gastroenterology department of DMCH. Results: The mean age of patients was 31.69±10.01 years, with 75% being male. Among all patients, the majority (45%) of them were service holders, and most of them (58.6%) lived in urban areas. Among IBS subtypes, 57% had IBS-D, and 42% had IBS-M. SIBO was detected in 36.5% (38 patients), with a significantly higher prevalence in IBS-D patients (53.3%) compared to IBS-M patients (13.7%) (p<0.001). No significant associations were found between SIBO status and demographic factors such as age, gender, marital status, occupation, or smoking. Conclusions: The study findings show that SIBO is more prevalent in IBS-D patients than in IBS-M, suggesting a potential role of bacterial overgrowth in the pathophysiology of IBS-D. The frequency of SIBO among IBS-D and IBS-M was 36.5% and IBS-D was the only factor associated with SIBO.