Does Long-term Inhibition of Gastric Acid Secretion with Omeprazole Lead to Small Intestinal Bacterial Overgrowth?

Objective: Gastric acid secretion and small intestinal motility are the main mechanisms of defense against bacterial overgrowth of the proximal digestive tract. Bacterial colonization of the stomach during gastric acid inhibition has been documented, but is probably without clinical consequence. However, small intestinal bacterial overgrowth can have serious clinical implications with malabsorption and diarrhoea.

Methods: We prospectively investigated small intestinal bacterial overgrowth in 40 patients receiving long-term omeprazole treatment using the [14C]glycocholic breath test. Tests were performed before omeprazole treatment, after 6 weeks treatment with 40 mg o.m. and after 26 weeks treatment with 20 mg; in the test each patient served as his own control.

Results: Breath tests, using individual curves, peak values, time at which the peak appeared and the area under the curve, did not differ significantly during treatment from those before treatment.

Conclusions: We conclude that long-term strong inhibition of gastric acid secretion does not lead to small intestinal bacterial overgrowth.