Pneumococcal pneumonia: capsular polysaccharide antigenemia and antibody responses

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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

Published on: February 24, 2014

48.4K

J D Coonrod, D P Drennan

    Annals of Internal Medicine
    |March 1, 1976
    PubMed

    Insights

    Pneumococcal pneumonia patients with detectable capsular polysaccharide antigen in their blood (antigenemia) often experienced prolonged illness. This antigenemia, linked to bacteremia, also delayed the immune response, even with antibiotic treatment.

    Area of Science:

    • Medical Microbiology
    • Infectious Diseases
    • Immunology

    Background:

    • Pneumococcal pneumonia remains a significant global health concern.
    • The role of capsular polysaccharide antigenemia in disease severity and immune response requires further elucidation.

    Purpose of the Study:

    • To investigate the prevalence and clinical significance of capsular polysaccharide antigenemia in patients with pneumococcal pneumonia.
    • To assess the association between antigenemia, bacteremia, and specific serotypes.
    • To evaluate the impact of antigenemia on antibiotic therapy effectiveness and host immune response.

    Main Methods:

    • Serum samples from 46 patients with pneumococcal pneumonia were analyzed for capsular polysaccharide.
    • Antigenemia detection was correlated with clinical data, including bacteremia and serotype.
    • Changes in polysaccharide concentration and antibody development were monitored during antibiotic treatment.

    Main Results:

    • Capsular polysaccharide antigen was detected in 19 of 46 patients (41.3%).
    • Antigenemia showed a strong association with bacteremia and infection by low-numbered serotypes.
    • Circulating antigen persisted for at least 2 weeks in two-thirds of cases despite antibiotic therapy, and antibody development was delayed.

    Conclusions:

    • Capsular polysaccharide antigenemia is a notable finding in pneumococcal pneumonia, associated with more severe disease manifestations.
    • Persistent antigenemia may impair early host immune response, potentially contributing to prolonged illness despite effective antibiotic treatment.
    • Further research is needed to clarify the mechanisms behind delayed antibody development in the presence of circulating antigen.

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