Antigen detection for diagnosis of the endemic mycoses

Abstract

Introduction Endemic mycoses are major causes of morbidity and mortality in the Americas, Africa, and Asia. Coccidioidomycosis and blastomycosis are often overlooked in patients diagnosed with community-acquired pneumonia [1,2]. Patients with acute pulmonary histoplasmosis caused by a high inoculum exposure often present with diffuse pulmonary involvement that may progress to respiratory insuffi ciency [3,4]. Histoplasmosis usually causes progressive disseminated disease in immunosuppressed patients. In each of these mycoses, rapid diagnosis may allow the physician to initiate therapy early, potentially reducing morbidity and even preventing death. Antigen detection can be a sensitive and specifi c method for rapid diagnosis of the endemic mycoses, with a sensitivity of approximately 75% for extensive pulmonary infections and more than 90% for disseminated disease, and a specifi city of approximately 98%. The use of the Histoplasma antigen enzyme immunoassay (EIA) for diagnosis and management of acute pulmonary and progressive disseminated histoplasmosis is well documented [5]. Experience with the Blastomyces antigen EIA is growing and supports a similar role in the management of blastomycosis. A Coccidioides antigen EIA was developed in 2008 (Durkin, unpublished data), offering an additional approach to the rapid diagnosis of coccidioidomycosis. Whereas molecular methods have been described for detection of fungal nucleic acid in specimens from patients with endemic mycoses, superiority over other rapid methods has not been established, and reagents are not commercially available for routine use. Their role in the diagnosis of histoplasmosis is not yet established. This review updates information previously reported concerning the diagnosis of histoplasmosis and blastomycosis and presents new information on coccidioidomycosis. Earlier reviews provide more in-depth discussion of other aspects of fungal antigen detection [6], and other reviews provide information on the use of antigen detection for diagnosis of cryptococcosis, aspergillosis, and candidiasis [6–10].