CROSS-REACTIVITY IN HISTOPLASMA-CAPSULATUM VARIETY CAPSULATUM ANTIGENASSAYS OF URINE SAMPLES FROM PATIENTS WITH ENDEMIC MYCOSES

We evaluated cross-reactivity in the antigen assay used for the diagno sis of histoplasmosis by testing urine samples from patients with diss eminated fungal infections. The mycoses chosen for this study were sel ected on the basis of the observation that during clinical testing, cr oss-reactions may occur between Histoplasma capsulatum var, capsulatum , Paracoccidioides brasiliensis, Blastomyces dermatitidis, Coccidioide s immitis, and Penicillium marneffei. We detected antigen in 12 of 19 patients with blastomycosis, 8 of 9 with paracoccidioidomycosis, in 17 of 18 with P. marneffei infection, and in one with disseminated H. ca psulatum var, duboisii infection. Cross-reactions were not observed in the assays for six patients with disseminated coccidioidomycosis, Cro ss-reactivity between the agents of other endemic mycoses should be co nsidered in interpreting a positive H. capsulatum var. capsulatum anti gen assay, Antigen detection may provide a rapid, provisional diagnosi s for patients with serious infections caused by one of these organism s.