This assay indirectly detects anti-Blastomyces IgG by recognizing the BAD-1 repeat surface protein. During validation testing, the sensitivity was found to be 94.29% and specificity 95.00% with an assay cutoff of 14.0 EU. It offers an improvement over the current method of detecting antibodies by FID, where sensitivity has been reported as only 32%. Complement fixation is even less sensitive than FID.
The Blastomyces Antibody IgG EIA is useful for diagnosing blastomycosis in patients with negative antigen results. Secondly, when both Histoplasma and Blastomyces antigen assays are positive, comparing Histoplasma and Blastomyces antibody concentrations may assist in establishing the correct diagnosis. Additionally, following changes in antibody concentration via repeat testing may determine whether the infection has resolved or if relapse has occurred.
Semi-Quantitative Indirect Enzyme Immunoassay (EIA)
Specimens positive for Histoplasma capsulatum may cross-react with the Blastomyces Antibody EIA (IgG detection) and test positive (20% cross reactivity).
Serum: Collect serum specimens in serum separator or red top tube. Allow blood to clot for 30 minutes, then centrifuge. Pipette serum separated from clot into a plastic screw cap vial.
Plasma: Plastic screw cap vial
Serum/Plasma: 0.5 mL
Any specimen type other than serum
Ship to arrive Monday‐Friday using a next day delivery service. Samples may be shipped on dry ice, frozen ice packs, or ambient.
Testing is performed on Monday, Wednesday, Thursday and Friday.
Reported next day
Results should be correlated with clinical presentation and history.