Background: Blastomycosis is an uncommon granulomatous infection caused by the thermally dimorphic fungus Blastomyces dermatitidis. The most frequent clinical infections involve the lung, skin, and bone. Pulmonary manifestations range from asymptomatic self-limited infection to severe diffuse pneumonia causing respiratory failure.
Objectives: To establish the clinical characteristics and outcomes of patients with pulmonary blastomycosis diagnosed at hospitals in Manitoba and northwestern Ontario, Canada.
Methods: A retrospective review of medical records was done for 318 patients with blastomycosis in these regions.
Results: The majority of patients were Caucasian (198 (62.5%) patients), male (193 (61%) patients), and residents of Ontario (209 (65.7%) patients). Most patients were treated in an inpatient hospital ward (266 (84%) patients) and survived (294 (92%) patients). Pulmonary involvement, either alone or associated with other sites, was present in 296 (93%) of the 318 patients; 22 (7%) patients had no evidence of pulmonary blastomycosis. The majority of patients had localized lung disease (1-3 quadrants on chest radiograph involved; 225 (82%) patients). Of 294 (92%) patients requiring hospitalization, 266 (90%) patients received all inpatient care on a general medical ward; 28 (10%) patients received some care in the intensive care unit (ICU). Factors associated with ICU admission included diffuse pulmonary disease (four quadrants involved on chest radiograph), diabetes, and prior use of antimicrobial therapy. Twenty-four (8%) patients died, and multivariate analysis showed that older age and Aboriginal ethnicity were the significant risk factors for death from blastomycosis.
Conclusion: Blastomycosis is a cause of serious, potentially life-threatening pulmonary infection in this geographic region.