361. Changing Epidemiology of Blastomyces dermatitidis Infection in Quebec, Canada: A Retrospective Multicenter Study

Abstract

BackgroundIn the wake of the increased incidence of blastomycosis in Quebec province, Canada, clinicians have observed a possible increase of severity in patients, with occasional death. This study aimed to assess temporal changes in blastomycosis severity and mortality in Quebec, and to identify risk factors for mortality of blastomycosis.MethodsA retrospective multicenter cohort study of patients with confirmed blastomycosis identified in a database at the provincial laboratory (Laboratoire de santé public du Québec) between 1988 and 2016. Severe cases were defined as patients with septic shock and/or acute respiratory distress syndrome and/or requiring mechanical ventilation. Immunosuppression included corticosteroid use, HIV, immunosuppressive therapy for inflammatory disease, chemotherapy, and transplantation. The primary outcome was 90-day all-cause mortality. Risk factors for mortality were identified by multivariate logistic regression.ResultsOver the study period, 220 blastomycosis cases were identified. Medical charts for 176 patients from 17 institutions were available and complete for data collection. The median age of patients was 55.3 years (interquartile range 45–67). Infection led to hospitalization of 119 patients (68%). Pulmonary involvement was recorded for 81% of cases (142/176) and two organs or more were involved in 35% (61/176). An increase in severity was observed mainly in recent years [1988–1997: 1/32 (3%); 1998–2007: 9/54 (17%); 2008–2016: 19/89 (21%); P = 0.05]. The overall mortality was 17.6% (31/176); 6% (2/33) in 1988–1997, 20% (n = 11/54) in 1998–2007 and 20% in 2008- 2016 (n = 18/89) (P = 0.15). There was also a significant increase in age at diagnosis (P = 0.005), the proportion of diabetic patients (P = 0.03) and the proportion of immunocompromised patients (P = 0.009) over time. The independent risk factors of mortality were age (aOR 1.03 for each additional year, 95% CI 1.0–1.06, P = 0.05) and immunosuppression (aOR 3.62, 95% CI 1.54–8.49, P = 0.003).ConclusionThe severity of blastomycosis observed in Quebec over the past 30 years has increased. These changes could be explained in part by an increase in the number of immunosuppressed patients. However, mortality has remained stable in recent years.Disclosures All authors: No reported disclosures.