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Immunity to pneumococcal surface proteins in children with community-acquired pneumonia: a distinct pattern of

K M Posfay-Barbe1, A Galetto-Lacour, S Grillet

  • 1Departments of Child and Adolescent Medicine and Pathology-Immunology, University of Geneva, Geneva, Switzerland. Klara.PosfayBarbe@hcuge.ch

Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases
|November 3, 2010
PubMed

Insights

Diagnosing pneumococcal pneumonia in children is hard. Adding antibodies to pneumococcal surface proteins (PSPs) to anti-pneumolysin (Ply) tests significantly improved detection of recent pneumococcal exposure in children with community-acquired pneumonia (CAP).

Area of Science:

  • Pediatric infectious diseases
  • Immunology
  • Microbiology

Background:

  • Diagnosing community-acquired pneumonia (CAP) in children, especially identifying pneumococcal causes, presents significant challenges.
  • Serological markers are needed to accurately assess pneumococcal CAP (P-CAP) prevalence in epidemiological studies.

Purpose of the Study:

  • To evaluate the diagnostic utility of anti-pneumolysin (Ply) antibodies alone and in combination with antibodies against four pneumococcal surface proteins (PSPs) for identifying P-CAP in hospitalized children.
  • To assess the sensitivity and specificity of these serological markers in detecting recent pneumococcal exposure.

Main Methods:

  • Compared serological responses to anti-Ply and four PSPs (PhtD, PhtE, LytB, PcpA) in children with CAP.
  • Defined recent pneumococcal exposure by positive blood culture, Ply(+) PCR, and/or PSP seroresponse.
  • Analyzed antibody titers (ELISA Units/mL) and used regression analysis to identify predictors of P-CAP.

Main Results:

  • Anti-Ply antibodies alone identified 31% of P-CAP cases; adding PSP seroresponses increased detection to 45% (sensitivity from 0.44 to 0.94).
  • Convalescent anti-Ply and anti-PhtD antibody titers were significantly higher in P-CAP patients, confirming recent exposure.
  • Low acute anti-PcpA antibody titers at admission independently predicted P-CAP (p=0.002), distinguishing it from non-pneumococcal CAP.

Conclusions:

  • Novel PSP seroresponses significantly enhance the detection of recent pneumococcal exposure in children with CAP.
  • Low acute anti-PcpA antibody levels are a key indicator for diagnosing P-CAP in pediatric patients.
  • These serological markers offer improved diagnostic capabilities for epidemiological research on pneumococcal pneumonia in children.

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