β-d-Glucan as a Diagnostic Adjunct for Invasive Fungal Infections: Validation, Cutoff Development, and Performance in Patients with Acute Myelogenous Leukemia and Myelodysplastic Syndrome

The Glucatell (1→3)-β-d-glucan (BG) detection assay (Associates of Cape Cod) was studied as a diagnostic adjunct for invasive fungal infections (IFIs). On the basis of findings from a preliminary study of 30 candidemic subjects and 30 healthy adults, a serum BG level of ⩾60 pg/mL was chosen as the cutoff. Testing was performed with serial serum samples obtained from 283 subjects with acute myeloid leukemia or myelodysplastic syndrome who were receiving antifungal prophylaxis. At least 1 serum sample was positive for BG at a median of 10 days before the clinical diagnosis in 100% of subjects with a proven or probable IFI. IFIs included candidiasis, fusariosis, trichosporonosis, and aspergillosis. Absence of a positive BG finding had a 100% negative predictive value, and the specificity of the test was 90% for a single positive test result and ⩾96% for ⩾2 sequential positive results. The Glucatell serum BG detection assay is highly sensitive and specific as a diagnostic adjunct for IFI.