Antigen detection, serology, and molecular diagnosis of invasive mycoses in the immunocompromised host

Abstract

Understanding the uses and limitations of methods for rapid diagnosis of fungal disease is essential in order to diagnose and treat these infections early in their course. Antigen detection methods are useful for diagnosis of aspergillosis, cryptococcosis, histoplasmosis, blastomycosis, paracoccidioidomycosis, and penicilliosis marneffei. The accuracy of the beta-glucan assay for diagnosis of aspergillosis and candidiasis and its role in fungal diagnosis remains unclear, in part because the few published studies report widely varying specificity. Serologic tests for antibodies are also useful for diagnosis of histoplasmosis and coccidioidomycosis, but their sensitivity may be reduced by immunosuppression. While molecular diagnostic methods have been described and are available at some reference and university laboratories, their role in patient care remains uncertain, largely because of the lack of well-characterized assays and studies establishing their accuracy. Culture methods, although essential for establishing the diagnosis in some cases, have limitations for rapid diagnosis, namely insensitivity, need for invasive procedures, and delayed growth.

Evaluation of an Enzyme Immunoassay for Detection of Histoplasma capsulatum Antigen from Urine Specimens

“…It is well documented that, for patients who have been previously diagnosed with histoplasmosis, serial monitoring of Histoplasma antigen levels can be used to monitor the response to therapy, whereby significant decreases in antigen levels are commonly associated with favorable outcomes while consistently elevated or increasing antigen levels may suggest treatment failure (3,19). Also, some patients who are clinically improving may continue to In addition to our prospective study, we were able to evaluate the performance of the IMMY ASR EIA using 11 urine samples collected from patients with culture-confirmed histoplasmosis.…”

Serum Aspergillus galactomannan antigen values strongly correlate with outcome of invasive aspergillosis

“…We selected serum GMI as an outcome variable because the test is Aspergillus-specific, objective, quantitative, and shown to be an accurate measure of fungal load 9 and a validated surrogate endpoint for aspergillosis outcome. [10][11][12] We also evaluated survival because it is an important and objective clinical outcome.…”

Clinical Significance of Low-Positive Histoplasma Urine Antigen Results

“…Available diagnostic modalities for histoplasmosis include fungal culture, nucleic acid amplification tests (NAAT), histopathologic examination of tissue biopsy specimens, and Histoplasma antibody and antigen detection from body fluids. Among these methods, Histoplasma antigen detection from urine offers high clinical sensitivity for identification of patients with disseminated disease compared to alternative diagnostic methodologies (1)(2)(3). Additionally, Histoplasma antigen levels decline during disease resolution and are therefore monitored as a measure of patient response to therapy (4).…”