Association between Chronic Use of Proton Pump Inhibitors and Small-Intestinal Bacterial Overgrowth Assessed using Lactulose Hydrogen Breath Tests

Background/Aims: Several adverse events have been reported in patients who are chronic users of proton pump inhibitors (PPIs); however, the association between PPI use and small-intestinal bacterial overgrowth (SIB 0) is controversial. We examined the prevalence of SIBO, as assessed by the lactulose hydrogen breath test (LHBT), based on the use of gastric acid-suppressive drugs in Japanese patients: Methodology: Ninety-four patients who were examined by the LHBT were assessed retrospectively. We used several criteria to define a positive LHBT result. Nine patients received probiotics containing Lactobacillus casei. Results: Fifty patients were PPI users, 14 were histamine-2 receptor antagonist (H2RA) users, and were 30 non-PPI and non-H2RA users (controls). There were no significant differences in prevalence of LHBT-positive cases among the three groups. Multiple-adjusted regression showed no significant association between PPI use and being LHBT-positive. Prevalence of postprandial fullness in PPI users was high (46%), but such symptoms were not related to LHBT results. Four (44%) of 9 cases became LHBT-negative and the maximal peak of H-2 production decreased significantly after probiotic treatment. Conclusions: PPI treatment is not associated with SIBO in Japanese patients. Mechanisms apart from SIBO could cause the high prevalence of postprandial fullness in PPI users.