Enzyme Immunoassay versus Latex Agglutination Cryptococcal Antigen Assays in Adults with Non-HIV-Related Cryptococcosis

We compared paired enzyme immunoassay (EIA) and latex agglutination (LA) assay results with 185 blood and 164 cerebrospi-nal fluid (CSF) samples from 44 and 33 non-HIV cryptococcosis patients, respectively. The LA assay cutoff of 1:256 in the blood and 1:32 in the CSF was most highly predictive of a positive EIA result. The EIAmissed 18.4 % detected by the LA assay in the blood samples and 7.8 % detected by the LA assay in the CSF samples. We note here the improved sensitivity of the LA assay over the EIA in non-HIV patients. Cryptococcus neoformans and Cryptococcus gattii are majorcauses of fungal meningoencephalitis in HIV-infected and-uninfected individuals. The polysaccharide capsule of these spe-cies is a virulence factor and is a major diagnostic tool used in clinical practice (1). Although there aremany commercially avail-able kits, the enzyme immunoassay (EIA) and latex agglutination (LA) test predominate. However, the LA assay requires the per-formance of a time-consuming and operator-variable visually as-sessed agglutination assay and requires repetitive dilutions for highly positive specimens, whereas the EIA utilizes an automated spectrophotometric method (2). Previous studies comparing var-ious platforms have been performed on blood and cerebrospina