title: Positive (1-3) B-d-glucan and cross reactivity of fungal assays in coccidioidomycosis.
abstract: Fungal antigen testing in immunosuppressed patients has emerged as a powerful diagnostic tool. Some assays are relatively nonspecific, and misinterpretation can have severe clinical consequences. Additionally, when new assays become commercially available it is important to evaluate the potential for cross reactivity. We recently observed several immunosuppressed patients with positive (1→3)-β-D-glucan (BG) who were eventually diagnosed with coccidioidomycosis in the endemic area of Tucson, Arizona. Although the BG assay is known to detect glucans of many fungal pathogens, reports of cross-reactivity with Coccidioides remain sparsely reported. To test the cross-reactivity of fungal antigens in detection assays, serum samples from patients with coccidioidomycosis testing positive for Coccidioides antigen were evaluated for BG. Of 12 samples positive for Coccidioides antigen (≥0.07 ng/ml), 11 (92%) were positive by BG (>80 pg/ml), and of 11 positive for Aspergillus galactomannan, 10 (91%) were positive by BG (>80 pg/ml). We conclude that the BG assay is nonspecific, detecting glucans from many fungal pathogens, including Coccidioides. In the endemic area, a positive BG warrants further specific testing.
authors.affiliation: University of Arizona College of Medicine, Division of Infectious Diseases, Tucson, Arizona tzangeneh@deptofmed.arizona.edu.
authors.forename: Tirdad T
authors.initials: TT
authors.lastname: Zangeneh
authors.affiliation: University of Arizona College of Medicine, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Tucson, Arizona.
authors.forename: Joshua
authors.initials: J
authors.lastname: Malo
authors.affiliation: University of Arizona College of Medicine, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Tucson, Arizona.
authors.forename: Carmen
authors.initials: C
authors.lastname: Luraschi-Monjagatta
authors.affiliation: Indiana University School of Medicine, Department of Pulmonary Medicine, Indianapolis, Indiana.
authors.forename: Chadi A
authors.initials: CA
authors.lastname: Hage
authors.affiliation: MiraVista Diagnostics, Indianapolis, Indiana.
authors.forename: L Joseph
authors.initials: LJ
authors.lastname: Wheat
authors.affiliation: University of Arizona College of Medicine, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Tucson, Arizona.
authors.forename: Christopher
authors.initials: C
authors.lastname: Strawter
authors.affiliation: University of Arizona College of Medicine, Division of Infectious Diseases, Tucson, Arizona.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Klotz
authors.affiliation: University of Arizona College of Medicine, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Tucson, Arizona.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Knox
mesh_terms: D001130:Arizona; D001228:Aspergillosis / Q000175:diagnosis; D003045:Coccidioides / Q000302:isolation & purification; D003047:Coccidioidomycosis / Q000175:diagnosis*; D003429:Cross Reactions; D005189:False Positive Reactions; D006801:Humans; D016867:Immunocompromised Host; D011509:Proteoglycans; D012680:Sensitivity and Specificity; D047071:beta-Glucans / Q000097:blood*
chemical_list: D011509:Proteoglycans; D047071:beta-Glucans; C010770:polysaccharide-K
keywords: Coccidioidomycosis; galactomannan; glucan; immunoassay