Does Probiotic Use Increase the Risk for Developing Small Intestinal Bacterial Overgrowth? Presidential Poster

Purpose: Small intestinal bacterial overgrowth (SIBO) results in diarrhea, bloating, and/or malabsorption. A previous review of patients undergoing duodenal culture in 2003 found 8% had SIBO. A recent, but small sample of patients undergoing aspirate culture showed a higher rate of 40%. We postulated that probiotics—which are not formulated for colonic release—may be a risk factor for SIBO. Specific Aims: 1) To estimate the prevalence of SIBO among patients referred for culture. 2) To identify the clinical risk factors for SIBO. 3) To examine whether probiotic use may be a risk factor for SIBO. Methods: A retrospective chart review of a random sample of 250 patients who had undergone duodenal aspirate culture at an academic medical center between January 2010 and October 2011 was performed. A positive culture was defined as culture counts >105 cfu/ml; an intermediate result was >0 but <105 cfu/ml; a negative result was no growth. Associations between clinical characteristics, medications, probiotic use, and aspirate results were assessed using multiple variable logistic regression analysis (response being 3 aspirate result categories, “negative” as the reference). Results: 221 (88%) patients had available aspirate results. The median age of the sample was 54 (range: 16-88) and 144 (65%) were females. 92 (42%) had positive cultures; 55 (25%) had no growth. Adjusted for age and gender, the following were associated with aspirate Results: age, PPI use, and narcotic use (Table, left column). Probiotic use (yogurt and supplement use), IBS, inflammatory bowel disease, pancreatitis, small bowel diverticula, GI surgery, and intestinal pseudoobstruction were not associated with aspirate result. Of the 48 patients using probiotics, 19 (40%) had a positive aspirate compared to 73 (42%) in those not using probiotics (N.S.). In the final model (Table, right column), increasing age increased the odds of a positive result, whereas both PPI use and narcotic use increased the odds of an intermediate and positive aspirate result. Conclusion: The prevalence of culture-positive SIBO has increased in the last several years. Based on this pilot study, the most important clinical features predictive of SIBO were increasing age, PPI use, and narcotic use, but not major GI comorbidity or probiotic use.Figure: [291]