S1316 Distinctive Clinical Correlates of Small Intestinal Bacterial Overgrowth With Methanogens

Abstract

INTRODUCTION: Small intestinal bacterial overgrowth (SIBO) is defined as the presence of >105 colony forming units of bacterial organisms/mL in the jejunum or ileum. SIBO presents with a plethora of non-specific GI symptoms and is associated with conditions such as dysmotility disorders, surgical alteration of gut anatomy, and immune deficiencies. About 30% of patients with SIBO are colonized with species of Archaea, anerobic bacteria-like organisms that produce methane and are resistant to standard antibiotics. METHODS: A retrospective analysis of breath test data from patients evaluated for SIBO at a busy academic health center between 8/1/18 to 9/1/19 was performed. Before testing, patients completed a standard questionnaire on the presence/absence of symptoms and conditions often associated with SIBO. A baseline breath sample was obtained; a 50g oral glucose load was given; alveolar breath samples were obtained at 15-min intervals for 2 hrs and analyzed with a Quintron Breath Tracker. The presence of SIBO was defined as a rise in breath hydrogen and/or methane concentration >20 ppm over baseline within 1 hour; studies not meeting these criteria were deemed SIBO(-). The significance of differences in symptom and condition frequency among groups determined by chi square analysis at P < 0.05. RESULTS: Of 616 patients, 190 (30.8%) were SIBO(+); of these, 104 (54.7%) produced only hydrogen; 53 (27.9%) produced only methane; and 33 (17.4%) produced both hydrogen and methane. SIBO(+) patients who produced only methane reported less diarrhea than those who produced hydrogen or were SIBO(-) (41.5% vs 55.5% vs 59.2%, P = 0.047), and had a lower frequency of diabetes (15.1% vs 28.5% vs 15.5%, P = 0.002), cholecystectomy (20.8% vs 42.3% vs 34.7%, P = 0.019), RYGB (P = 0.012), dumping syndrome (P = 0.028), and displayed a trend to less vitamin B12 deficiency (P = 0.091). CONCLUSION: These data reveal that SIBO caused by methane-producing Archaea is associated with distinctive clinical correlates compared to SIBO caused by hydrogen-producing-bacteria. This suggests that methanogenic SIBO may involve unique pathogenic mechanisms mediated by a differential sensitivity of Archaean physiology to specific host factors, such as the impact of diabetes and GI surgery on intestinal mucosal function and motility and/or the effect of cholecystectomy on luminal bile acid concentration. Mechanistic investigations of these distinctive clinical correlates could lead to novel approaches to treat SIBO with methanogens.Figure 1.: SIBO with Methanogens.