A Multicenter Evaluation of Tests for Diagnosis of Histoplasmosis

TLDR

The lack of evaluation of antigenemia sensitivity in disseminated histoplasmosis after immune‑complex dissociation and antibody denaturation methods has been noted. The study aimed to determine the sensitivity of the current antigen assay across different histoplasmosis categories. Urine and serum specimens from 218 histoplasmosis patients and 229 controls, including 30 blastomycosis cases, were tested. The assay detected antigenuria in 91.8 % of disseminated, 83.3 % of acute, 30.4 % of subacute, and 87.5 % of chronic pulmonary cases, antigenemia in all 31 disseminated cases, with higher sensitivity in immunocompromised and severe patients, 99 % specificity in non‑fungal and healthy controls, 90 % cross‑reactivity with blastomycosis, and comparable antigenemia and antigenuria sensitivity in disseminated disease.

Abstract

The sensitivity of the MVista Histoplasma antigen enzyme immunoassay (MiraVista Diagnostics) has been evaluated in disseminated histoplasmosis in patients with AIDS and in the "epidemic" form of acute pneumonia. Moreover, there has been no evaluation of the sensitivity of antigenemia detection in disseminated histoplasmosis after the implementation of methods to dissociate immune complexes and denature released antibodies. The goal of this study was to determine the sensitivity of the current antigen assay in different categories of histoplasmosis.Urine and serum specimens obtained from 218 patients with histoplasmosis and 229 control subjects, including 30 with blastomycosis, were tested.Antigenuria was detected in 91.8% of 158 patients with disseminated histoplasmosis, 83.3% of 6 patients with acute histoplasmosis, 30.4% of 46 patients with subacute histoplasmosis, and 87.5% of 8 patients with chronic pulmonary histoplasmosis; antigenemia was present in 100% of 31 tested cases of disseminated histoplasmosis. Among patients with disseminated cases, antigenuria was detected more often and at higher concentrations in immunocompromised patients and those with severe disease. Specificity was 99.0% for patients with nonfungal infections (n = 130) and in healthy subjects (n = 69), but cross-reactivity occurred in 90% of patients with blastomycosis.The sensitivity of antigen detection in disseminated histoplasmosis is higher in immunocompromised patients than in immunocompetent patients and in patients with more severe illness. The sensitivity for detection of antigenemia is similar to that for antigenuria in disseminated infection.