Suppression of gastric acid secretion in patients with gastroesophageal reflux disease results in gastric bacterial overgrowth and deconjugation of bile acids

The aim of this study was to test the hypothesis that gastric bacterial ove rgrowth is a side effect of acid suppression therapy in patients with gastr oesophageal reflux disease (GERD) and that the bacteria-contaminated gastri c milieu is responsible for an increased amount of deconjugated bile acids. Thirty patients with GERD who were treated with 40 mg of omeprazole for at least 3 months and 10 patients with GERD who were off medication for at le ast 2 weeks were studied.. Ar the time of upper endoscopy, 10 mi of gastric fluid was aspirated and analyzed for bacterial growth and bile acids. Bact erial overgrowth was defined by the presence of more than 1000 bacteria/ml. Bile acids were quantified via highperformance liquid chromatography. Elev en of the 30 patients taking omeprazole had bacterial overgrowth compared t o one of the 10 control patients. The median pH in the bac ter ia-positive patients was 5.3 compared to 2.6 in those who were free of bacteria and 3.5 in the control patients who were off medication. Bacterial overgrowth only occurred when the pH was >3.8. The ratio, of conjugated to unconjugated bi le acids changed from 4:1 in the patients without bacterial overgrowth to 1 :3 in those with bacterial growth greater than 1000/ml. Proton pump inhibit or therapy in patients with GERD results in a high prevalence of gastric ba cterial overgrowth. The presence of bacterial overgrowth markedly increases the concentration of unconjugated bile acids. These findings may have impl ications in the pathophysiology of gastroesophageal mucosal injury