RIDASCREEN® Entamoeba histolytica IgG

Intended use:

For in vitro diagnostic use. The RIDASCREEN® Entamoeba histolytica IgG test is an enzyme immunoassay for the qualitative determination of IgG antibodies against Entamoeba histolytica in human serum. The test should be used for confirmation purposes when there is a suspected case of amoebiasis.

General information:

Infection with E. histolytica occurs orally with the intake of cysts. The vegetative form of the parasite develops from these cysts in the small intestine. This trophozoite multiplies and differentiates mostly in the colon. The clinical symptoms of an amebiasis are triggered by the invasion of parasites from the intestinal lumen into the mucous membrane of the colon. Diarrhea, dysentery or even ameboma are results of the invasion into the intestinal mucosa. If dissemination occurs, further complications can be liver abscesses, lung abscesses or in rare cases even brain abscesses, which can be fatal if left untreated. If an extraintestinal amebiasis was suspected, sonography should be the method of the choice. Since this method cannot always differentiate an abscess caused by E. histolytica from other abscesses or carcinoma, an antibody detection should be made to support other clinical findings. Antibodies are usually detectable with the beginning of the clinical symptoms. Due to the often negative results in case of an abscess, the antigen detection in stool is not sufficient. Direct detection of Entameba in the punctate is not of importance, because ameba are rarely detectable in abscess material.

Test principle:

Purified antigens are coated to a microwell plate. Antibodies in the patient samples bind to the antigens and are determined during the second step by using enzyme-labelled Protein A (the conjugate). The enzyme converts the colourless substrate (H₂O₂/TMB) to a blue end product. The enzyme reaction is stopped by adding sulphuric acid and the colour of the mixture switches from blue to yellow at the same time. The final measurement is carried out at 450 nm on a photometer using a reference wavelength ≥ 620 nm.