Clinical Significance of Serum (1→3)-β-D-Glucan Positivity in Cryptococcosis: A Retrospective Cohort Study

Cryptococcosis is associated with negative serum (1→3)-β-D-glucan (BDG) results, but the clinical significance of serum BDG (sBDG) positivity is unclear. We characterized the clinical features of sBDG-positive cryptococcosis in patients with cryptococcal disease. We measured the sBDG levels and classified patients as BDG-positive (>11 pg/mL) or BDG-negative. Clinical characteristics, diagnostic modalities, antifungal treatment, post-treatment BDG level changes, and 90-day cryptococcosis-related mortality were compared. BDG-positive patients showed disseminated cryptococcosis, higher inflammatory marker levels, lower serum albumin levels, higher culture positivity rates, and higher cryptococcal antigen titers than BDG-negative patients. Combination antifungal therapy was administered more frequently in the BDG-positive group; repeat measurements in 15 patients showed a significant decrease in sBDG levels. The 90-day mortality rate was significantly higher in the BDG-positive than in the BDG-negative group (37.5% vs. 3.9%), and overall survival was significantly lower. sBDG levels may be elevated in cases of disseminated or severe disease. Serum BDG positivity may reflect a higher fungal burden, greater disease severity, and poorer short-term outcomes.