1156 - Clinical and epidemiological features and outcomes of Blastomycosis in a tertiary hospital in Kentucky

Background: Blastomycosis is an endemic dimorphic fungal infection caused by Blastomyces dermatitidis. The risk factors associated with severe presentation are not well defined.

Methods: Retrospective study of patients treated for blastomycosis at the University of Kentucky Hospital from 2004-2019. Statistical analyses were performed with STATA version 12.0 (College Station, Texas). Logistic regression was used to identify variables associated with severe infections.

Results: Among 82 patients, median age was 48 years old (range: 16 - 89); 66 (80.5%) were male and 71 (92.2%) were white, 25/77 (32.4%) were obese, 24 (29.2%) were diabetic, 21 (25.6%) had COPD, 26 (31.7%) had at least one immunosuppressive condition. The median duration of illness was 86 (3-365) days.  37 (45.1%) had cough and 35 (42.6%) had dyspnea 19 (23.1%) patients were treated in the ICU, 42 (51.3%) in non-ICU inpatient wards, and 21 (25.6%) in an outpatient setting. Cultures were obtained in 69 cases, 59 (85.5%) reported as positive, KOH stain positive in 30/61 (49.1%). Histopathology was positive in 48/66 (72.7%) samples. Urine Histoplasma or Blastomyces antigen was positive in 41/58 (70.6%), and Serum Histoplasma or Blastomyces antigen was positive in 22/34 (64.7%). Among 64 (78.0%) patients with pulmonary blastomycosis, acute and chronic pneumonia were 16 (25.0%) and 12 (18.7%) cases respectively, and nodular lung lesions were reported in 36 (56.2%).  Initial antifungal treatment was amphotericin B liposomal in 38/80 (47.5%), overall mortality was 11 (13.4%). A multivariable analysis was performed to find predictors of severe blastomycosis infection, no association was seen with factors as male sex (IRR 1.96; 95%CI 0.84 – 4.55), and was confirmed that significant independent associated risk factors for severe infection were age older than 50 (IRR 3.5; 95%CI 1.42-8.83), obesity (IRR 3.1; 95% CI 1.41-6.87), diabetes (IRR 2.5; 95% CI 1.16-5.50), leukocytosis (IRR 1.03; 95%CI 1.00-1.07) and anemia (IRR 3.0; 95% CI 1.55-5.85).

Conclusion: Pulmonary Blastomycosis is the most common presentation. Culture and histopathology are more sensitive than antigen assay. Independent factors associated to severe disease were older age, obesity, diabetes, and anemia at admission.