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Scientific article
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Immunity to pneumococcal surface proteins in children with community-acquired pneumonia: a distinct pattern of responses to pneumococcal choline-binding protein A

Published inClinical microbiology and infection, vol. 17, no. 8, p. 1232-1238
Publication date2011
Abstract

The aetiological diagnosis of community-acquired pneumonia (CAP) is challenging in children, and serological markers would be useful surrogates for epidemiological studies of pneumococcal CAP. We compared the use of anti-pneumolysin (Ply) antibody alone or with four additional pneumococcal surface proteins (PSPs) (pneumococcal histidine triad D (PhtD), pneumococcal histidine triad E (PhtE), LytB, and pneumococcal choline-binding protein A (PcpA)) as serological probes in children hospitalized with CAP. Recent pneumococcal exposure (positive blood culture for Streptococcus pneumoniae, Ply(+) blood PCR finding, and PSP seroresponse) was predefined as supporting the diagnosis of presumed pneumococcal CAP (P-CAP). Twenty-three of 75 (31%) children with CAP (mean age 33.7 months) had a Ply(+) PCR finding and/or a ≥ 2-fold increase of antibodies. Adding seroresponses to four PSPs identified 12 additional patients (35/75, 45%), increasing the sensitivity of the diagnosis of P-CAP from 0.44 (Ply alone) to 0.94. Convalescent anti-Ply and anti-PhtD antibody titres were significantly higher in P-CAP than in non P-CAP patients (446 vs. 169 ELISA Units (EU)/mL, p 0.031, and 189 vs. 66 EU/mL, p 0.044), confirming recent exposure. Acute anti-PcpA titres were three-fold lower (71 vs. 286 EU/mL, p <0.001) in P-CAP children. Regression analyses confirmed a low level of acute PcpA antibodies as the only independent predictor (p 0.002) of P-CAP. Novel PSPs facilitate the demonstration of recent pneumococcal exposure in CAP children. Low anti-PcpA antibody titres at admission distinguished children with P-CAP from those with CAP with a non-pneumococcal origin.

Keywords
  • Adhesins, Bacterial/immunology
  • Antibodies, Bacterial/blood
  • Bacterial Proteins/genetics/immunology
  • Carrier Proteins/immunology
  • Child, Preschool
  • Community-Acquired Infections/diagnosis/immunology
  • Humans
  • Lipoproteins/immunology
  • Membrane Proteins/immunology
  • Pneumonia, Pneumococcal/diagnosis/immunology
  • Sensitivity and Specificity
  • Streptococcus pneumoniae/immunology
  • Streptolysins/genetics/immunology
Citation (ISO format)
POSFAY BARBE, Klara et al. Immunity to pneumococcal surface proteins in children with community-acquired pneumonia: a distinct pattern of responses to pneumococcal choline-binding protein A. In: Clinical microbiology and infection, 2011, vol. 17, n° 8, p. 1232–1238. doi: 10.1111/j.1469-0691.2010.03389.x
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Article (Published version)
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ISSN of the journal1198-743X
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