Evaluation of an Iranian Home-made Helicobacter pylori Stool Antigen ELISA Kit

Current diagnosis of Helicobacter pylori infection by biopsy-based tests requires invasive sampling. Non-invasive methods such as the H. pylori stool-antigen (HpSA) test may be the best alternative for diagnosis of active infection. However, due to the presence of antigenic-diversity among the strains, various commercial tests have shown some discrepancies in different geographical-areas.

This study evaluates a homemade HpSA kit developed by using the H. pylori antigens from Iranian-isolates for detection of H. pylori in the stool of infected patients.

Based on the endoscopic features and/or a rapid-urease test (RUT), 30 child and 50 adult patients, were recruited. From these candidates, three biopsies for RUT, culture and histology, and a stool-sample, were obtained. Patients were considered as H. pylori-positive if culture alone or RUT plus histology were found to be positive. Presence of H. pylori antigens in their stools was detected by the homemade HpSA test and an imported HpSA kit (Immundiagnostik, Germany).

Using the biopsy-based tests with RUT, histology and culture, 53% (16/30) of children were diagnosed as H. pylori-positive while using the imported kit 57% and the homemade kit 50% of the candidates showed positive results. Also by the biopsy-based tests, 54% of the adults were diagnosed as H. pylori-positive while by the homemade kit 56% showed positive results. Considering the biopsy-based tests as the gold standard, sensitivity and specificity for the imported kit was 94% and 86%, respectively, while the mean sensitivity and specificity for the homemade kit was 96% and 98%, respectively.

The homemade kit, compared with the imported kit and biopsy-proven tests may be a valid and reliable method for determining the presence of H. pylori infection in Iran.