Clinical Update
New Test: Beta(β)-D-Glucan Assay
In-house Beta(β)-D-Glucan (BDG) testing is now available.
The assay diagnoses certain systemic fungal infections, such as Candidemia, and assists in the prognostication and monitoring response to anti-fungal therapy in hospitalized patients.
This FDA-approved test is a protease zymogen-based colorimetric assay (FUNGITELL® ASSAY) based on a modification of the Limulus Amebocyte Lysate (LAL) pathway in which BDG, where present in the sample, binds Factor G. Activated Factor G turns a proclotting enzyme to clotting enzyme. The latter cleaves an artificial chromogenic substrate (a short peptide) to generate a color. The reaction occurs at 37°C and is kinetically read by a spectrophotometer to generate a standard curve and sample readouts that are subsequently converted to BDG concentrations in pg/ml.
It is important to note that certain fungi, such as the genus Cryptococcus that produces very low levels of BDG, may not result in serum BDG levels sufficiently elevated to be detected by the assay. Infections with fungi of the order Mucorales, such as Absidia, Mucor, and Rhizopus, that are not known to produce BDG can also yield non-detectable serum BDG levels. In addition, the yeast phase of Blastomyces dermatitidis produces little BDG and may not be detected by the assay. Furthermore, positive BDG results have been seen in hemodialysis patients, those who received certain fractionated blood products (such as albumin, IVIg), and those exposed to glucan-containing gauze or surgical sponges.
The sample should be centrifuged within 2 hours of collection to separate the serum from the cells.
Separated samples or serum should be stored refrigerated pending delivery to the testing laboratory.
Heel and fingerprick collections are unacceptable.
Test Name
(1,3) B-D Glucan
Test Code
BDGLUC
CPT Code
87449
Methodology
Protease zymogen-based colorimetric assay (FUNGITELL® ASSAY)
Specimen Requirements
Type: Serum
Volume: 0.5 mL
Container: Gold BD Hemogard™ Serum Separation Tubes (SST)™
Transport Temperature: Refrigerated
Stability
Ambient: Unacceptable
Refrigerated: 7 days
Frozen: 1 year
Reference Range
Negative; <60 pg/mL
Reportable Range
31 to 500 pg/mL
Days Performed
Monday, Wednesday, Friday