title: Elevated inflammatory markers combined with positive pneumococcal urinary antigen are a good predictor of pneumococcal community-acquired pneumonia in children.
abstract: BACKGROUND
  Our objective was to evaluate procalcitonin (PCT) and C-reactive protein (CRP) as predictors of a pneumococcal etiology in community-acquired pneumonia (CAP) in hospitalized children.
  
  
  METHODS
  Children requiring hospitalization for CAP were prospectively enrolled. The following indices were determined: antibodies against pneumococcal surface proteins (anti-PLY, pneumococcal histidine triad D, pneumococcal histidine triad E, LytB and pneumococcal choline-binding protein A), viral serology, nasopharyngeal cultures and polymerase chain reaction for 13 respiratory viruses, blood pneumococcal polymerase chain reaction, pneumococcal urinary antigen, PCT and CRP. Presumed pneumococcal CAP (P-CAP) was defined as a positive blood culture or polymerase chain reaction for Streptococcus pneumoniae or as a pneumococcal surface protein seroresponse (≥2-fold increase).
  
  
  RESULTS
  Seventy-five patients were included from which 37 (49%) met the criteria of P-CAP. Elevated PCT and CRP values were strongly associated with P-CAP with odds ratios of 23 (95% confidence interval: 5-117) for PCT and 19 (95% confidence interval: 5-75) for CRP in multivariate analysis. The sensitivity was 94.4% for PCT (cutoff: 1.5 ng/mL) and 91.9% for CRP (cutoff: 100 mg/L). A value≤0.5 ng/mL of PCT ruled out P-CAP in >90% of cases (negative likelihood ratio: 0.08). Conversely, a PCT value≥1.5 ng/mL associated with a positive pneumococcal urinary antigen had a diagnostic probability for P-CAP of almost 80% (positive likelihood ratio: 4.59).
  
  
  CONCLUSIONS
  PCT and CRP are reliable predictors of P-CAP. Low cutoff values of PCT allow identification of children at low risk of P-CAP. The association of elevated PCT or CRP with a positive pneumococcal urinary antigen is a strong predictor of P-CAP.
authors.affiliation: From the *Division of Pediatric Emergency Medicine; †Department of Child and Adolescent Medicine, Geneva University Hospitals and University of Geneva, Geneva; ‡Child and Adolescent Department, University Hospital, Lausanne, Switzerland; §Sanofi Pasteur, Marcy l'Etoile, France; and ¶Sanofi Pasteur, Toronto, Canada.
authors.forename: Annick
authors.initials: A
authors.lastname: Galetto-Lacour
authors.forename: Gabriel
authors.initials: G
authors.lastname: Alcoba
authors.forename: Klara M
authors.initials: KM
authors.lastname: Posfay-Barbe
authors.forename: Manon
authors.initials: M
authors.lastname: Cevey-Macherel
authors.forename: Mario
authors.initials: M
authors.lastname: Gehri
authors.forename: Martina M
authors.initials: MM
authors.lastname: Ochs
authors.forename: Roger H
authors.initials: RH
authors.lastname: Brookes
authors.forename: Claire-Anne
authors.initials: CA
authors.lastname: Siegrist
authors.forename: Alain
authors.initials: A
authors.lastname: Gervaix
mesh_terms: D000942:Antigens, Bacterial / Q000652:urine; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002097:C-Reactive Protein / Q000378:metabolism; D002116:Calcitonin / Q000097:blood; D015740:Calcitonin Gene-Related Peptide; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000097:blood* / Q000382:microbiology / Q000652:urine*; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D008297:Male; D011018:Pneumonia, Pneumococcal / Q000097:blood* / Q000382:microbiology / Q000652:urine*; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood; D013296:Streptococcus pneumoniae / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000942:Antigens, Bacterial; D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide