Comparison of the one-gramd-[14C]xylose breath test to the [14C]bile acid breath test in patients with small-intestine bacterial overgrowth

Abstract

In twelve patients with culture-proven bacterial overgrowth of the small intestine, the ability of a newly-developed one-gramd-[¹⁴C]xylose breath test to detect bacterial overgrowth was compared to that of the [¹⁴C]bile acid breath test. All patients manifested excessive production of breath¹⁴CO₂ after the administration of one gram [¹⁴C]xylose, with 83% of the patients being abnormal within the first hour of testing. In contrast, during the [¹⁴C]bile acid breath test, four of the twelve patients had no period of excessive¹⁴CO₂ production (above the 95% confidence range of controls). Nutrient malabsorption (fat, cobalamin, xylose) was seen with both true-positive and false-negative bile acid breath tests. The one gram [¹⁴C]xylose breath test, utilizing a substrate with more predominant absorption in the proximal small intestine and which can be catabolized by Gram-negative aerobic bacteria, appears to have a greater degree of sensitivity and specificity than the bile acid breath test in detecting the presence of small-intestine bacterial overgrowth.