Helicobacter pylori antigens in stool specimens of gastritis children before and after treatment

Background: Various testing methods are successfully applied to the diagnosis of Helicobacter pylori infection, but noninvasive techniques are still needed for therapeutic monitoring, especially in children. In the search for new noninvasive techniques for the diagnosis of H. pylori infection, the authors evaluated an enzyme immunoassay for the detection of H. pylori antigen in stool (HpSA). Methods: The authors studied 62 H. pylori-positive children with chronic gastritis and 45 control subjects. H. pylori infection was diagnosed using cultures and histology of gastric biopsy specimens and a stool antigen test before treatment (clarithromycin, amoxicillin, omeprazole for 7 days) and 4 weeks to 6 weeks after treatment. Results: Before therapy, antigen in stool was detected in 55 of 62 H. pylori-positive patients, which indicates that the sensitivity of the HpSA test was 88.7%. Of the 45 control subjects (with negative culture and histology results), 43 had negative results for H. pylori in the stool test (specificity, 95.5%). After completion of therapy, eradication was obtained (and confirmed by culture and histology) in 53 of the 62 H. pylori-positive children (85.5%). Four weeks to 6 weeks after eradication therapy, the sensitivity, specificity, positive predictive value, and negative predictive value of the stool antigen (HpSA) test were 88.9%, 96.2%, 80%, and 98%, respectively. Conclusions: The accuracy of the HpSA test for the detection of H. pylori in human stool 4 weeks to 6 weeks after treatment is comparable with the accuracy of the culture results. The stool antigen (HpSA) test was found to be a useful method for post-treatment eradication testing of H. pylori infection in children.