Systemic fungal infections: diagnosis and treatment. I. Blastomycosis.

Blastomycosis is a rare systemic fungal infection caused by Blastomyces dermatitidis, which is often difficult to diagnose because of its spectrum of manifestations, varying severity, and unusual occurrence in most geographic areas. Because routine serologic methods and skin tests are not reliable for this pathogen, diagnosis is made by visualization of the organism in tissue, sputum, or exudate, or by culture. Once blastomycosis is diagnosed, therapeutic options include treatment with amphotericin B or ketoconazole, or simple observation if spontaneous resolution is anticipated. The purpose of this discussion is to review the features of blastomycosis that relate to the clinical practice of medicine.