Small Intestinal Bacterial Overgrowths and Intestinal Methanogen Overgrowths Breath Testing in a Real-Life French Cohort

Breath testing has become a widely used tool to diagnose small intestinal bacterial overgrowths (SIBOs) and intestinal methanogen overgrowths (IMOs) in clinical settings. Owing to the heterogeneity in clinical manifestations and lack of standardization among centers performing breath testing, SIBO and IMO can be easily overlooked by the clinician. We studied the prevalence and symptoms of SIBO/IMO in French patients referred for breath testing after seeking medical advice. METHODS: Breath test data and symptoms of 331 patients were assessed for SIBO/IMO using the H(2)/CH(4) lactulose breath test (LBT). Wilcoxon test or χ(2) test were used to compare patients with SIBO/IMO with patients without SIBO/IMO. LBT positive patients (H(2)+, CH(4)+, and CH(4)+/H(2)+) were compared using Kruskal-Wallis test for continuous data or χ(2) test for categorical data. RESULTS: Among the 186 (68.1%) patients tested positive for an overgrowth with 40.3%, 47.3%, and 12.4% for H(2)+, CH(4)+ and CH(4)+/H(2)+, respectively, the presence of diarrhea was significantly increased in hydrogen type overgrowths (P < 0.001). No significant difference according to age, gender, and symptoms was associated with a positive test except for joint pain that was less prevalent among LBT positive patients (P = 0.038). In 86.5% of IMOs, positivity with CH(4) values ≥10 ppm could be identified at baseline. DISCUSSION: There are little discriminating symptoms that can help the clinician to identify patients likely to have a SIBO/IMO. However, SIBO/IMOs remain a common disorder widely underdiagnosed that need further studies to better apprehend functional bowel disorders.