Evaluation of a novel rapid one-step immunochromatographic assay for detection of monoclonal Helicobacter pylori antigen in stool samples from children

A new rapid one-step immunochromatographic test using monoclonal antibodies for detection of Helicobacter pylori antigen in stool in children was evaluated on coded stool samples from 159 children (mean age, 9.7 +/- 5.0 years; 118 from Munich, 41 from Vienna): 86 children were H. pylori infected defined by positive culture and/or > or =2 other positive tests ([13C]urea breath test, histology, rapid urease test), and 73 children showed concordant negative results. Seventy-nine patients (12.1 +/- 3.8 years; 42 from Munich; 37 from Vienna) were tested 6 to 8 weeks after anti-Helicobacter pylori therapy with urea breath test and stool test. In Munich, all 160 tests (118 pre- and 42 posttreatment) were independently read by two observers. Equivocal results were excluded for calculation of sensitivity and specificity but were considered as false to assess accuracy. The two observers in Munich agreed in 63 out of 65 positive and 89 out of 95 negative results, while eight times (5.0%) they judged the test as equivocal. Pretreatment and posttreatment results for sensitivity were 88.1% (79.2 to 94.1) and 88.9% (51.8 to 99.7), specificity 88.1% (77.8 to 94.1) and 93.9% (85.2 to 98.3), and accuracy 83.5% and 81.5%, respectively. We conclude that the new monoclonal immunochromatographic quick test shows a good interobserver agreement, but equivocal results occur in 5%. Performance is comparable before and after therapy. The test may become a good alternative in children in settings where a [13C]urea breath test or a reliable enzyme immunoassay stool test are not available.