Community-acquired fungal pneumonias

Abstract

Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, and Cryptococcus neoformans can cause acute community-acquired pneumonia. All are soil-dwelling fungi and disturbance of contaminated soil is necessary for infection in man. Each has particular epidemiologic considerations that may offer a clue to diagnosis, but the clinical presentation is not sufficiently characteristic to be of diagnostic help. Infection may produce variable symptoms, ranging from asymptomatic skin test conversion to fulminant respiratory failure. Chest roentgenograms are likewise nonspecific. Rapid microscopic diagnosis of Histoplasmosis in pulmonary secretions is seldom possible while blastomycosis and coccidioidomycosis may be seen in KOH digested sputum. Culture of H capsulatum and B dermatitidis usually takes several weeks, should not be attempted with C immitis, and is rapid with Cr neoformans. Serodiagnosis also takes several weeks and is usually not helpful while the patient is symptomatic. Treatment may not be necessary unless the patient is immunosuppressed, seriously ill, or has life threatening complications. The primary pulmonary infection may disseminate to extrapulmonary sites, which always requires treatment.