Diagnosis of blastomycosis

During the 100 years since Blastomyces dermatitidis was discovered as a cause of human disease, diagnostic tests, methods of collection of specimens, and laboratory techniques have improved significantly. Radiographic advances and the introduction of the fiberoptic bronchoscopy have allowed for more reliable clinical diagnoses. More sensitive serologic techniques and DNA probes have significantly improved the sensitivity of laboratory diagnosis. At present, the most reliable serologic tests are the sandwich enzyme immunoassay (sensitivity 88%, specificity 100%) and the 120-kd antigen radioimmunoassay (sensitivity 85%, specificity 100%). When positive and negative predictive values are applied, the sandwich enzyme immunoassay appears to be the most accurate. At the present time, a negative serologic test cannot be used to exclude blastomycosis. Further advances in refining the B dermatitidis antigen(s) for use in the newer, more sensitive, and specific assay techniques may allow for a definitive serologic diagnosis in the future, avoiding the necessity for invasive tests.