Evaluation of three different tests for the detection of stool antigens to diagnose Helicobacter pylori infection in patients with upper gastrointestinal bleeding

Aim: To evaluate the accuracy of several methods aimed to detect Helicobacter pylori stool antigens in patients with upper gastrointestinal bleeding. Methods: Thirty-four patients with upper gastrointestinal bleeding because of peptic ulcer were included. The first stool sample during hospitalization was collected, and stool antigens were determined with: polyclonal enzyme-linked immunosorbent assay (Premier-Platinum-HpSA); monoclonal enzyme-linked immunosorbent assay (Amplified-IDEIA-HpStAR); and rapid monoclonal immunochromatographic test (ImmunoCard-STAT HpSA). A patient was considered infected when H. pylori was diagnosed with invasive tests (rapid urease test or histology) or with C-13-urea breath test. When all tests were negative, a new breath test was repeated after stopping proton pump inhibitors. Results: All patients were infected and, therefore, only sensitivity of the tests could be calculated: polyclonal enzyme-linked immunosorbent assay (74%), monoclonal enzyme-linked immunosorbent assay (94%), and rapid monoclonal immunochromatographic test (60%; concordance between the two observers was high, kappa = 0.9). Neither the presence of maelena nor the delay in obtaining stool samples explained false negatives. Conclusions: Neither the polyclonal enzyme-linked immunosorbent assay stool antigen test nor the rapid immunochromatographic stool antigen test can be recommended to diagnose H. pylori infection in patients with upper gastrointestinal bleeding. However, the monoclonal enzyme-linked immunosorbent assay stool antigen test is highly sensitive for detecting the infection in patients with this complication, although more studies are necessary to evaluate the specificity of the method.