Fungitell, manufactured by Associates of Cape Cod Incorporated, is a reliable serum-based assay that takes 40 minutes to run. A key feature of this test is that it does not require culture. It is an enzymatic assay for (1,3)-beta-D glucan, a unique component of the fungal cell wall. Glucan is found in a number of medically important fungi such as Candida, Aspergillus, Fusarium, Acremonium, and Saccharomyces. The molecular basis for the test is the Limulus (horseshoe crab) coagulation cascade, which glucan readily activates. Fungitell is prepared from lysed amebocytes (crab blood cells), which are treated to remove the factor C (lipopolysaccharide-dependent) pathway and restrict the assay to the factor G (glucan-dependent) pathway. The pathway activates a clotting enzyme that cleaves p-nitroaniline from a chromogenic peptide substrate. This in turn allows photometric readout. The entire test can be carried out with standard laboratory equipment. A related assay, Glucatell, is available for non-diagnostic purposes, for example, to test for fungal contamination in buildings, water supplies, or pharmaceutical lots.
Other tests provide the ability to detect particular fungi. Platelia Aspergillus EIA, manufactured by Bio-Rad Laboratories, is a serum immunoassay for galactomannan, a specific component of the Aspergillus cell wall. Galactomannan is recognized by a specific rat antibody, which then allows enzyme-linked photometric readout. Like Fungitell, the test is independent of culture and supports turnaround time of about 3 hours. It is supplied on 96-well sandwich microplates and runs on standard equipment.
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