Multisite Clinical Evaluation of a Rapid Test for Entamoeba histolytica in Stool

Rapid point-of-care detection of enteric protozoa in diarrheal stool is desirable in clinical and research settings to efficiently determine the etiology of diarrhea. We analyzed the ability of the third-generationE. histolytica Quik Chek assay developed by Techlab to detect amebic antigens in fecal samples collected from independent study populations in South Africa and Bangladesh. We compared the performance of this recently released rapid test to that of the commercially available ProSpecTEntamoeba histolytica microplate assay from Remel and theE. histolytica II enzyme-linked immunosorbent assay (ELISA) from Techlab, using real-time and nested-PCR forEntamoeba species to resolve any discrepant results. After discrepant resolution, TheE. histolytica Quik Chek assay exhibited sensitivity and specificity compared to theE. histolytica II ELISA of 98.0% (95% confidence interval [CI], 92.9% to 99.8%) and 100% (95% CI, 99.0% to 100%), respectively. Compared to the ProSpecT microplate assay, theE. histolytica Quik Chek (Quik Chek) assay exhibited 97.0% sensitivity (95% CI, 91.5% to 99.4%) and 100% specificity (95% CI, 99.0% to 100%). Our results indicate that the Quik Chek is a robust assay for the specific detection ofE. histolytica trophozoites in unfixed frozen clinical stool samples.