Efficiency of crude and purified fungal antigens in serodiagnosis to discriminate mycotic from other respiratory diseases.

ABSTRACT

Mycotic immunodiagnosis was performed in 186 hospitalized patients with different respiratory diseases, mostly considered as tuberculosis and others with a doubtful diagnosis. Crude histoplasmin, coccidioidin, paracoccidioidin, blastomycin, candidin, aspergillin, and sporotrichin, as well as purified polysaccharide-protein complexes (PPC) of Histoplasma capsulatum, Coccidioides immitis, and Paracoccidioides brasiliensis were used as antigens. Immune tests used included skin test (ST), gel immunodiffusion (ID), counterimmunoelectrophoresis (CIE), complement fixation (CF), and ELISA. A possible association with candidosis was observed in 17% of patients with tuberculosis and diabetes; one presumptive paracoccidioidomycosis, one confirmed aspergillosis, and six cases of active histoplasmosis were determined. Candidin ST showed 29% of positive reactions with an increased frequency in patients between 31 and 55 years of age. CF test showed the highest positivity percentages with crude antigens, specially for Candida antigen (26.3%) and histoplasmin (18.2%). Cross reactions were evident with crude antigens but decreased when PPC's were used in ELISA.