Immunoassay Evaluated for Detection of Helicobacter pylori

The efficacy of a new polyclonal enzyme immunoassay (EIA) for the detection of Helicobacter pylori antigen in feces has been determined.

The immunoassay has been compared with histology, rapid urease test, carbon-13 (¹³C)-urea breath test, and serology to determine the optimal cut-off value for screening a population at risk.

Scientists at Seoul National University (Seoul, Korea) prospectively enrolled 515 patients undergoing a routine health check-up. H. pylori infection was defined if at least two of four of the following tests: histology, rapid urease test, ¹³C-urea breath test, and serology, were positive. Stool samples were analyzed using a new polyclonal EIA stool antigen test, the EZ-STEP H. pylori, which was performed by the capture of polyclonal antibodies to H. pylori absorbed in microwells. The optimal cut-off value was determined by the receiver–operator characteristic curve. The diagnostic performance of each test was evaluated with regard to the histological diagnosis of atrophic gastritis (AG)/intestinal metaplasia (IM), degree of AG/IM, and old age.

The EZ-STEP H. pylori stool antigen test (Dinona Inc., Seoul, Korea) had a sensitivity of 93.1%, and specificity of 94.6% and was accurate 93.8% of the time. The sensitivity of histology, rapid urease test, and the ¹³C-urea breath test ranged from 89.1% to 97.6%, and their specificity was greater than 98%. The serological test, an enzyme-linked immunosorbent assay, identified as the H. pylori IgG EIA Well (Radim diagnostics, Rome, Italy) had high sensitivity, but low specificity. The stool antigen test still showed good diagnostic performance in the setting of progression of AG/IM and in patients over 40 years.

The authors concluded that the diagnostic performance of the new polyclonal stool antigen EIA was comparable to that of other methods used in the diagnosis of H. pylori infection in the screening population if an optimal cut-off value was determined. The stool antigen test might still be effective for the detection of H. pylori in the clinical settings of AG and/or IM and elderly patients. The study was published in June 2011, in the Journal of Gastroenterology and Hepatology.

Related Links:
Seoul National University
Radim diagnostics