Comparison of an enzyme immunoassay for the detection ofHelicobacter pylori antigens in the faeceswith the urea breath test

摘要

BACKGROUND—Current diagnostic tests for Helicobacter pylori are invasive (endoscopy) or indirect (urea breath test, serology).
AIMS—To evaluate a new enzyme immunoassay (EIA) which detects H pylori antigens in faeces, by comparing its sensitivity and specificity in children with the ¹³C urea breath test (UBT).
METHODS—A total of 119 children underwent a UBT and provided a faecal sample for antigen testing within seven days. After an overnight fast each child provided a pretest breath sample, and samples at 30 and 40 minutes after ingestion of 100 mg ¹³C labelled urea. ¹³C enrichment of breath was measured by isotope ratio mass spectrometry. Faeces were stored at −70°C until antigen testing, using the EIA. Samples were read spectrophotometrically at 450 nm and results were interpreted using recommended cut offs of optical density <0.14 as negative, ⩾0.16 as positive, with ⩾0.14 and <0.16 representing equivocal results. Sensitivity and specificity were calculated using the manufacturer's cut off compared with UBT.
RESULTS—Sensitivity and specificity were 88% and 82%, respectively. Negative and positive predictivevalues were 97% and 58%.
CONCLUSIONS—The EIA is analternative, non-invasive, and easy to use method for the detection ofH pylori in children. Its high negative predictive value suggests a role in screening out uninfected children.