Measurement of serum antigen concentration by ultrasound-enhanced immunoassay and correlation with clinical outcome in meningococcal disease

M. A. Sobanski, R. A. Barnes*, S. J. Gray, A. D. Carr, Edward Kaczmarski, A. O'Rourke, K. Murphy, M. Cafferkey, R. W. Ellis, K. Pidcock, P. Hawtin, W. T. Coakley

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    12 Citations (Scopus)

    Abstract

    The distribution of Neisseria meningitidis serogroup B and C polysaccharide antigen in blood and the prognostic significance of antigen concentration was examined by ultrasound-enhanced immunoagglutination of coated microparticles. Specimens (169 sera/plasma from 145 patients with confirmed meningococcal disease) were tested retrospectively. The ultrasonic immunoassay detected serum antigen in 136 samples from 112 patients. Titration of antigen-positive specimens allowed estimation of blood antigen concentration. The modal blood antigen titre was 1/16, corresponding to an estimated polysaccharide concentration of 0.85 μg/ml. The lowest mean blood antigen concentration found ultrasonically was 0.05 μg/ml; compared to the 1.98 μg/ml found by conventional latex agglutination, this represents an approximately 30-fold improvement in sensitivity. Three grades of outcome were correlated with the presenting antigen titre in 83 patients: (i) < 2 weeks hospitalisation, (ii) ≥ 2 weeks hospitalisation and (iii) mortality. High polysaccharide concentrations correlated with mortality. Nine of 15 patients with a serum antigen titre of 1/64 or greater (≥ 3.4 μg/ml polysaccharide) died, whereas no patient with titres equal to or less than 1/4 (≤ 0.21 μg/ml) died, including those patients in whom antigen was undetectable by ultrasonic immunoassay. Increasing antigen concentration significantly correlated with severity of outcome (P < 0.001). Ultrasound-enhanced agglutination provides a rapid prognostic indicator by sensitive measurement of serum antigen level.

    Original languageEnglish
    Pages (from-to)260-266
    Number of pages7
    JournalEuropean Journal of Clinical Microbiology and Infectious Diseases
    Volume19
    Issue number4
    DOIs
    Publication statusPublished - 2000

    Bibliographical note

    Funding Information:
    Acknowledgements The authors are grateful to the Meningitis Research Foundation (UK) for support and in part the Biotechnology and Biological Sciences Research Council (UK) Analytical Biotechnology Initiative.

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