Reference Information FAQs
Reactivity of the Reagent FAQs
Does the Fungitell® reagent react to analytes other than (1→3)-β-D-glucan?
How does the Fungitell® assay work?
How sensitive is the Fungitell® assay?
Sample Preparation
What kind of sample does the Fungitell® assay require?
Are there any interferences that would reject a sample?
Do immunoglobulinemias affect the assay?
Do the endogenous proteases of serum affect the assay?
Clinical Interpretation FAQs
Do all invasive fungal infections result in high serum levels of (1→3)-β-D-glucan?
Is (1→3)-β-D-glucan always in the positive range during a fungal infection?
How often should a patient be tested?
Does a positive value always mean that the patient has a fungal infection?
Does the Fungitell® reagent react to analytes other than (1→3)-β-D-glucan?
No. Only (1→3)-β-D-glucan has been shown to be reactive to Fungitell. Factor G, the beta-glucan sensing component is very specific for the (1→3)-β-linked glucan structure.
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How does the Fungitell® assay work?
This is described in the instructions for use. The Fungitell assay works as an amplification cascade that allows a small stimulus to produce a large output signal. (1→3)-β-D-glucan activates a protease zymogen that, in turn, activates many molecules of another protease zymogen. This protease cleaves a chromogenic substrate, producing the increase in the optical density at 405 nanometers. This amplification accounts for the extreme sensitivity of the Fungitell assay.
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How sensitive is the Fungitell® assay?
The Fungitell assay can detect as little as a few picograms of (1→3)-β-D-glucan per mL.
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What kind of sample does the Fungitell® assay require?
The test has been developed and cleared to measure (1→3)-β-D-glucan in serum.
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Are there any interferences that would reject a sample?
Yes. Lipemia, Hyperbilirubinemia, and hemolysis can cause a sample to be rejected. Of these, hemolysis is of greatest concern.
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Do immunoglobulinemias affect the assay?
The test does not use antibodies. Only factors that affect the optical properties of the assay matrix are known to affect the test. These include excessively colored or turbid specimens.
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Do the endogenous proteases of serum affect the assay?
The serum proteases are inactivated by the 10 minute incubation with the alkaline pre-treatment reagent.
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Do all invasive fungal infections result in high serum levels of (1→3)-β-D-glucan?
No. The vast majority of fungi produce (1→3)-β-D-glucan. However, a few fungal genera produce little or no (1→3)-β-D-glucan. These include Cryptococcus, which yields low levels of serum (1→3)-β-D-glucan and the Zygomycetes (Rhizopus, Mucor, Cunninghamella, Absidia, etc.). A negative result does not rule out the presence of one of these genera.
The Fungitell assay is indicated for presumptive diagnosis of fungal infection. It should be used in conjunction with other diagnostic procedures, such as microbiological culture, histological examination of biopsy samples and radiological examination.
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Is (1→3)-β-D-glucan always in the positive range during a fungal infection?
No. (1→3)-β-D-glucan levels are highly variable and are dependent upon many factors including affected tissue, organism, underlying conditions, time in course of infection, etc. Clinical studies have generally observed rising levels of glucanemia, with worsening infection. Conversely, studies have also shown declining levels with successful therapy.
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How often should a patient be tested?
2-3 times per week. Serum (1→3)-β-D-glucan levels are dynamic.
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Does a positive value always mean that the patient has a fungal infection?
No. The entire clinical context must be considered. A number of potential sources of (1→3)-β-D-glucan contamination should be considered. These include recent surgery with exposure to cotton surgical sponges, etc., and contaminated blood fractionation products, The Fungitell assay is indicated as an adjunct to diagnosis and is to be considered with other clinical signs and symptoms in the development of a diagnosis.
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