Detection of Blastomyces dermatitidis antigen in patients with newly diagnosed blastomycosis.

Blastomycosis is a serious and potentially fatal infection, and diagnosis can be difficult at times. We evaluated the diagnostic utility of a commercially available assay for detection of Blastomyces dermatitidis antigen, recently modified to permit quantitation, in subjects with newly diagnosed blastomycosis. Twenty-three of 27 (85.1%) subjects had detectable B. dermatitidis antigenuria. In 2 of these 23, positive results were obtained after concentration of the urine specimen. Nine of 11 (81.8%) subjects had detectable B. dermatitidis antigen in serum, including 3 subjects with negative results before treatment of serum with ethylenediaminetetraacetic acid (EDTA) and positive results after EDTA treatment. B. dermatitidis antigen was not detected in specimens from 50 control subjects but was detected in 15 patients with histoplasmosis. B. dermatitidis antigen was detected in most of the patients with blastomycosis and can be a useful tool for timely diagnosis.