Bacterial overgrowth without clinical malabsorption in elderly hypochlorhydric subjects

Bacterial overgrowth of the small intestine commonly occurs in association with hypochlorhydria caused by atrophic gastritis or during treatment with omeprazole. The purpose of this study was to determine the clinical significance of bacterial overgrowth on small intestinal absorption and permeability and to evaluate the reliability of noninvasive breath tests to detect bacterial overgrowth in subjects with hypochlorhydria.

Seventeen healthy, elderly subjects with atrophic gastritis or omeprazole treatment (40 mg/day) and documented bacterial overgrowth were studied.

There was no evidence of fat malabsorption (72-hour fecal fat) or clinically significant carbohydrate malabsorption (25 g D-xylose and fecal pH) in any subject. The ratio of lactulose to mannitol excreted was normal in both atrophic gastritis and omeprazole-treated groups. Three subjects in each group had abnormally high alpha 1-antitrypsin clearances. Lactulose (10 g) and glucose (80 g) hydrogen breath tests were only abnormal in 1 out of 17 subjects, whereas the 1 g [14C]D-xylose test was abnormal in 6 out of 17 subjects.

Bacterial overgrowth caused by atrophic gastritis or omeprazole treatment is typically not associated with clinically significant fat or carbohydrate malabsorption. Noninvasive breath tests for bacterial overgrowth are not reliable in subjects with hypochlorhydria.