The Infectious Diseases Society of America has published guidelines for the treatment of blastomycosis. Selection of an appropriate therapeutic regimen must be based on the clinical form and severity of the disease, the immune status of the patient, and the toxicity of the antifungal agent (Table 113-1). Although spontaneous cures of acute pulmonary infection are well documented, there are no criteria by which to distinguish patients whose disease will progress or resolve without treatment. Thus all patients with blastomycosis should be treated.
Itraconazole is the agent of choice for immunocompetent patients with mild to moderate pulmonary or non-CNS extrapulmonary disease. Therapy is continued for 6–12 months. Amphotericin B (AmB) is the preferred initial treatment for patients who are severely immunocompromised, who have life-threatening disease or CNS disease, or whose disease progresses during treatment with itraconazole. Although not rigorously studied, lipid formulations of AmB provide an alternative for patients who cannot tolerate AmB deoxycholate. Most patients with non-CNS disease whose clinical condition improves after an initial course of AmB (usually 2 weeks in duration) can be switched to itraconazole to complete 6–12 months of therapy. Fluconazole, because of its excellent penetration of the CNS, is useful in the treatment of patients with brain abscess or meningitis after an initial course of AmB.
Voriconazole has been used successfully to treat refractory blastomycosis, blastomycosis in immunosuppressed patients, and—given its good penetration of cerebrospinal fluid—CNS disease. Posaconazole has also been used for refractory pulmonary disease. The echinocandins have variable activity against B. dermatitidis and therefore are not used in the treatment of blastomycosis.