The serological diagnosis of staphylococcal infective endocarditis

R W Watkin1, S Lang, P A Lambert

  • 1Department of Cardiology, Queen Elizabeth Hospital, Edgbaston, Birmingham B15 2TH, UK.

The Journal of Infection
|January 31, 2006
PubMed
Abstract

Insights

New serological assays can rapidly identify Staphylococcus aureus infective endocarditis (IE). Measuring IgG against whole cells or lipid S offers a faster diagnosis for this severe heart valve infection.

Area of Science:

  • Infectious Diseases
  • Immunology
  • Cardiology

Background:

  • Diagnosing infective endocarditis (IE) is challenging with sterile blood cultures or inconclusive echocardiography.
  • Staphylococcus aureus is a frequent cause of IE, leading to severe valve damage and high mortality.
  • Early, culture-independent diagnostic tests are crucial for prompt antibiotic treatment.

Purpose of the Study:

  • To develop and evaluate two novel serological assays for rapid identification of staphylococcal IE.
  • To measure IgG responses against whole Staphylococcus aureus cells and a novel antigen, lipid S.
  • To assess the diagnostic utility of these assays in patients with suspected IE.

Main Methods:

  • Enzyme-linked immunosorbent assay (ELISA) was used to measure serum IgG levels.
  • Serum samples were collected from 130 IE patients and 94 controls.
  • Assays measured IgG against whole Staphylococcus aureus cells and against lipid S.

Main Results:

  • Anti-lipid S IgG titres were significantly higher in IE patients compared to controls (p<0.0001).
  • Anti-lipid S IgG titres were higher in staphylococcal IE than in IE caused by other microorganisms (p=0.0003).
  • Anti-whole cell Staphylococcus aureus IgG titres were significantly higher in staphylococcal IE patients (p<0.0001).

Conclusions:

  • High anti-whole cell IgG titres predict a staphylococcal cause of IE.
  • Elevated anti-lipid S IgG titres indicate Gram-positive infection, with very high titres suggesting staphylococcal IE.
  • These serological assays show promise for the rapid diagnosis of staphylococcal infective endocarditis.

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