1050. Blastomyces dermatitidis Antigen Detection by Quantitative Enzyme Immunoassay
Session: Poster Abstract Session: Fungal Diagnosis
Saturday, October 22, 2011
Room: Poster Hall B1
Handouts
  • IDSA2011 Poster v2.png (259.5 kB)
  • Blastomyces dermatitidis antigen detection by quantitative enzyme immunoassay Patricia Connelly, Chadi A Hage, J Ryan Bariola, Eric Bensadoun, Mark Rodgers, Robert W Bradsher, L Joseph Wheat Background: The second generation MVista® Blastomyces antigen enzyme immunoassay was not quantitative, thus prior specimens were tested in the same assay as new specimens to assess the change in antigen levels. Furthermore, the sensitivity in serum had not been fully evaluated. The purpose of this study is to evaluate a quantitative Blastomyces antigen assay and detection of antigen in serum. Methods: Calibrators containing known concentrations of Blastomyces galactomannan were used to quantitate antigen in urine and serum specimens from patients with proven blastomycosis and controls. Paired current and prior urine specimens were tested to determine if quantification eliminated the need for concurrent testing to determine change in antigen levels. Pretreatment of serum with ethylene diamine tetra-acetic acid at 100° C was evaluated to determine if dissociation of immune complexes improved detection of antigenemia. Results: Antigenuria was detected in 89.9% of patients with culture or histopathology proven blastomycosis. Specificity was 99.0% in patients with non-fungal infections and healthy subjects, but cross reactions occurred in 95.6% of patients with histoplasmosis. Change in antigen level categorized as increase, no change or decrease based on antigen units determined in the same assay agreed closely with the category of change in ng/mL determined from testing current and prior specimens in different assays. Pretreatment of serum increase the sensitivity for detection of antigenemia from 35.7% to 57.1%. Conclusion: Quantification eliminated the need for concurrent testing of current and prior specimens for assessment in changes in antigen concentration. Pretreatment increased the sensitivity for detection of antigenemia. Differentiation of histoplasmosis and blastomycosis is not possible by antigen detection.

    Subject Category: M. Mycology including clinical and basic studies of fungal infections

    L Wheat, MD1, Patricia Connolly, MS1, Chadi A. Hage2, J Bariola, MD3, Robert Bradsher, MD4, Eric Bensadoun5 and Mark Rodgers1, (1)MiraVista Diagnostics, Indianapolis, IN, (2)Indiana University, Indianapolis, IN, (3)Div of Inf Dis, Univ of Ark Med Sci, Little Rock, AR, (4)University of Arkansas for Medical Sciences, Little Rock, AR, (5)medicine, University of Kentucky, Lexington, KY

    Disclosures:

    L. Wheat, MiraVista diagnostics: Employee and president and owner MiraVista diagnostics, Salary

    P. Connolly, MiraVista diagnostics: Employee, Salary

    C. A. Hage, None

    J. Bariola, None

    R. Bradsher, None

    E. Bensadoun, None

    M. Rodgers, MiraVista diagnostics: Employee, Salary

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