The 13 Urea Breath Test for the Noninvasive Detection ofHelicobacter pylori in Children: Comparison with Culture and Determination of Minimum Analysis Requirements

Background: The purpose of the study was to determine the accuracy of the labelled 13 carbon urea breath test for the diagnosis of Helicobacter pylori in children and to simplify the 13 carbon urea breath test in identifying the most discriminating sampling time. Methods: H. pylori was searched for in 100 children aged 10.5 ± 4.5 years by histology, bacteriological counts, and culture on antral biopsies together with serology and 13 carbon urea breath test. Breath samples were obtained before ingestion (T0) of 75 mg urea- 13 C and every 10 minutes after until T60. 13 CO 2 excess ratio was measured by isotope ratio mass spectrometry, and values expressed as delta per mil over baseline enrichment (δ 13 CO 2 ). The arithmetic mean (Mδ 13 CO 2 ) of T20 to T60 values was calculated and the test considered positive with Mδ 13 CO 2 higher than Mδ 13 CO 2 + 3 SD as determined in noninfected children. Results: Mδ 13 CO 2 of noninfected children as assessed by culture was 1.4 ± 0.6 per mil, determining a positive cut-off value of 3.44 per mil. Mδ 13 CO 2 was correlated in 11 children with biopsy bacteriological counts. Both culture and 13 carbon urea breath test were positive in 38 of 100 children, without any discordance. Plotting 13 carbon urea breath test results at each sampling time versus Mδ 13 CO 2 showed weaker correlations at T20, T30, T50, and T60, than at T40. The two-sample method at T0 and T30, T40, T50, had high sensitivity and specificity. Single-sample analysis obtained at T40 gave a comparable sensitivity and a slightly reduced specificity. Conclusion: 13 carbon urea breath test is sensitive and specific in children. Two samples collected at T0 and T40 provide the most discriminating procedure.