Comparison of monoclonal antibody-based stool antigen tests to determine the results of Helicobacter pylori eradication therapy

Objective. Stool antigen tests using monoclonal antibody are used to test the results of eradication therapy of Helicobacter pylori. A newly developed test using multiple monoclonal antibodies is considered to have higher sensitivity. The aim of this study was to examine whether monoclonal antibody-based stool antigen tests are equally applicable to determine the results of eradication therapy. Materials and methods. Stool specimens obtained from patients infected with H. pylori were diluted by human stool and tested by both Testmate pylori antigen enzyme immunoassay (TPAg EIA) and Premier Platinum HpSA PLUS (HpSA ELISA II). A total of 239 patients infected with H. pylori received eradication therapy and 5-8 weeks after finishing the treatment, stool samples were tested by TPAg EIA and HpSA ELISA II. On the same day of stool collection, all the patients received (13)C-urea breath test (UBT). Results. After 5 x dilution, optical density (OD) values of TPAg EIA were significantly reduced and three out of four stool specimens were tested negative after 10 x dilution. By contrast, three specimens were tested positive even after 100 x dilution by HpSA ELISA II. In the determination of eradication therapy, accordance between the two tests was 95.8%. Among 199 patients who tested negative by both stool antigen tests, 10 patients were positive by UBT. Overall accordance of TPAg EIA and HPSA ELISA II to UBT was 91.2% and 95.4%, respectively (NS). Conclusions. Although reduction of OD values was seen in TPAg EIA, it did not seem to cause false negative results in stool samples after eradication therapy. Both TPAg EIA and HpSA ELISA II were equally useful to determine the results of eradication therapy comparing with UBT.