Helicobacter pylori infection is associated with high methane production during lactulose breath test.

OBJECTIVE Despite a growing interest toward the interplay between H. pylori and gastric microbiota, few data are available about this correlation. The aim of this study was to explore the relationship between H. pylori infection and gas production during lactulose breath test. MATERIALS AND METHODS Data of patients undergoing both 13C-urea breath test (UBT) and lactulose breath test (LBT) under standard conditions in our GI unit were retrospectively analyzed. GI symptoms, such as dyspepsia, bloating, abdominal pain/discomfort, and epigastric pain on an eleven-point scale were also analyzed and correlate with the results of those tests. H2 and CH4 were calculated using the trapezoidal rule; a considerable CH4 production was defined by AUCCH4 ≥1200 ppm*4h. Statistical analyses were performed with Fisher's exact test and independent samples Mann-Whitney test. RESULTS Data of 136 patients during a period of time of 3 months were analyzed. 36 patients (26.5%) showed a positive UBT. We do not find any difference as regards age, sex, symptom complaints, and small intestinal bacterial overgrowth between HP negative and positive patients. A greater methane production was observed in infected rather than non-infected patients (47.2% vs. 26% respectively, p=0.02). Furthermore, 25% infected and 10% non-infected produced greater amounts of CH4 compared to H2, resulting in a AUCCH4/AUCH2 ratio >1 (p=0.046). CONCLUSIONS This study shows for the first time, a significant association between H. pylori infection and methane production, suggesting that H. pylori might influence gut microbiota composition. Further studies are needed to clarify mechanisms underlying this phenomenon.