"Reactivity of Cryptococcal Lateral Flow Assay in Aspergillosis, Histoplasmosis, Paracoccidioidomycosis, Candidiasis, Trichosporonosis, Bacterial and Viral infections".

Abstract

Considering the need for a rapid, sensitive, and specific test for the early diagnosis of cryptococcal meningitis in critical regions where lumbar puncture and culture are inaccessible, we analyzed the specificity of the Lateral Flow Assay for cryptococcal antigen (LFA) in 217 serum specimens. Group 1: 68 HIV-uninfected patients with paracoccidioidomycosis, histoplasmosis, aspergillosis, trichosporonosis and 21 with tuberculosis; Group 2: 149 patients with HIV infection, including seven with histoplasmosis, and one with aspergillosis, and Group 3 with 24 proven cryptococcosis patients. Cross-reactivity of cryptococcal mannans and polysaccharides secreted by Paracoccidioides brasiliensis, Histoplasma capsulatum, and Trichosporon spp has been described in vitro. However, only a few cases of positive LFA tests in aspergillosis, trichosporonosis, candidemia, and bacterial infections sera have been reported. We observed false-positive LFA in 2/29 aspergillosis specimens but not in other mycoses or tuberculosis. Among 149 HIV-infected patients, three specimens tested positive, two had cytomegalovirus infections, one of whom also had toxoplasmosis and the other, Kaposi's sarcoma; one patient had no opportunistic infections. We observed sensitivities of 0.933 (serum), 0.95 (CSF), and 1.0 (serum or CSF) for LFA, and for all negative controls (N = 217, serum), a specificity of 0.977 and a negative predictive value (NPV) of 0 938. The specificity and NPV were 0.964 and 0 791, respectively, for 55 patients with mycoses; and 0.98 and 0.912 for 149 HIV-infected patients. We confirmed LFA's high specificity and accuracy for the control groups. There were 6.89% of false-positive results for aspergillosis, and no false-positive results for paracoccidioidomycosis, histoplasmosis, tuberculosis, or other bacterial diseases.