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 (SIBO) 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. METH- ODOLOGY: 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 H2 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.