Measurement of serum (103)-b-D-Glucan (
Betaglucans) is an aid in the diagnosis of
fungemia and deep-seated mycoses, including invasive aspergillosis (IA).
Betaglucans is
present in the cell wall of most pathogenic fungi (includingPneumocystis jiroveci)
in significant amounts with some notable exceptions such as Cryptococcus
neoformans and Zygomycetes.
Commercially available assays can detect serum
Betaglucans concentrations as low as 1 pg/mL. Published validation studies have included
patients with IA and other invasive fungal diseases (IFD). Betaglucans detection appears to
be more sensitive than galactomannan detection in patients with IA, but Betaglucans’s
intrinsic lack of mycological specificity requires the integration of clinical,
radiological, and microbiological data for proper interpretation. Betaglucans assay test
characteristics can be used, for example, to exclude IA in some clinical scenarios
, to increase the certainty of IA in the presence of an isolated positive galactomannan
result or when testing follows initiation of antifungal treatment.
Betaglucans may be falsely
elevated in the serum in the absence of IFD in patients undergoing hemodialysis
with cellulose membranes, in patients treated with immunoglobulin, albumin, or
other blood products filtered through cellulose filters containing
Betaglucans, and in
patients with serosal exposure to glucan-containing gauze or to certain intravenous
antimicrobials.
These potential sources of false positivity should be considered
when interpreting
Betaglucans results.
Betaglucans may be useful as a sensitive screening tool for
surveillance of IA and other IFD in populations at risk. Stratified IFD screening
and diagnostic strategies using both galactomannan and
Betaglucans should be explored.
Factors affecting the production and clearance of
Betaglucans during IA and other IFD
need additional study to further refine its diagnostic utility.
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