Outcomes Associated With Blastomycosis in Solid Organ and Hematopoietic Cell Transplant Recipients.

Introduction: With reports of expanding epidemiology of blastomycosis across the United States, the purpose of this study was to evaluate the incidence and outcomes associated with blastomycosis in solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients.

Methods: We conducted a retrospective case series of adult SOT and HCT recipients at a tertiary care medical center between January 1, 2005 and September 30, 2023. Cases were defined as culture-proven blastomycosis. We performed descriptive statistical analysis to evaluate diagnosis, management, and outcomes (mortality) of blastomycosis in SOT.

Results: The cumulative incidence of blastomycosis was 0.11% with a median time to infection following transplant of 743 days. Of the 19 cases, the majority of patients were SOT recipients (90%). Supratherapeutic immunosuppression within 30 days of diagnosis was observed in 42% of cases with documented drug monitoring. Urine antigen testing was highly sensitive (100%). Fourteen (73.7%) patients received induction therapy with liposomal amphotericin B followed by azole therapy for a minimum of 12 months. Despite appropriate treatment, 1-year mortality was high at 26.3%, with attributable mortality of 21.1%.

Conclusions: While rates of blastomycosis remain low among SOT and HCT recipients, infection is associated with poor posttransplant outcomes. Antigen testing can aid in timely assessment of disease severity and initiation of appropriate therapy. Among survivors, no relapses were observed while on lifelong secondary suppression. Future studies should aim to better define risk factors associated with developing blastomycosis and establish effective strategies for prevention.