title: Etiology of childhood pneumonia: serologic results of a prospective, population-based study.
abstract: BACKGROUND
  To investigate the etiology of pediatric community-acquired pneumonia, we conducted a prospective, population-based study covering the total population <15 years of age (n = 8851) in 4 municipalities in eastern Finland.
  
  
  METHODS
  The number of patients was 201; chest radiographs were available for all cases and paired sera for serologic assays were available for >90% of cases. The methods included assays for antibody response to 3 pneumococcal antigens, specific pneumococcal immune complex assays and conventional antibody tests for mycoplasmal, chlamydial and viral infections.
  
  
  RESULTS
  Serologic evidence of specific microbial etiology was obtained in 133 (66%) of the pneumonia patients. Bacterial infection was diagnosed in 102 cases (51%) and viral infection in 51 cases (25%). Streptococcus pneumoniae was the most common agent (57 cases; 28%), followed by Mycoplasma pneumoniae (44; 22%), respiratory syncytial virus (43; 21%) and Chlamydia spp. (29; 14%). Haemophilus influenzae was identified in only 6% and Moraxella catarrhalis in only 3% of the children. More than one specific infection was found in 51 patients (25%). The proportion of pneumococcal cases varied from 24 to 36% by age. Mycoplasma infections were seen mostly in patients > or =5 years and Chlamydia infections in patients > or =10 years of age.
  
  
  CONCLUSIONS
  The results of our prospective, strictly population-based study confirm the importance of S. pneumoniae in the etiology of community-acquired pneumonia in children of all ages. M. pneumoniae and Chlamydia pneumoniae are important from the age of 5 years onwards.
authors.affiliation: Department of Pediatrics, Kuopio University Hospital, Finland. heiskane@messi.uku.fi
authors.forename: T
authors.initials: T
authors.lastname: Heiskanen-Kosma
authors.forename: M
authors.initials: M
authors.lastname: Korppi
authors.forename: C
authors.initials: C
authors.lastname: Jokinen
authors.forename: S
authors.initials: S
authors.lastname: Kurki
authors.forename: L
authors.initials: L
authors.lastname: Heiskanen
authors.forename: H
authors.initials: H
authors.lastname: Juvonen
authors.forename: S
authors.initials: S
authors.lastname: Kallinen
authors.forename: M
authors.initials: M
authors.lastname: Stén
authors.forename: A
authors.initials: A
authors.lastname: Tarkiainen
authors.forename: P R
authors.initials: PR
authors.lastname: Rönnberg
authors.forename: M
authors.initials: M
authors.lastname: Kleemola
authors.forename: P H
authors.initials: PH
authors.lastname: Mäkelä
authors.forename: M
authors.initials: M
authors.lastname: Leinonen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003141:Communicable Diseases; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007223:Infant; D011014:Pneumonia / Q000453:epidemiology / Q000382:microbiology*; D011446:Prospective Studies; D012698:Serologic Tests