title: Roentgenographic findings of pneumonia caused by Chlamydia pneumoniae. A comparison with streptococcus pneumonia.
abstract: BACKGROUND
  Pneumonia caused by Chlamydia pneumoniae or Streptococcus pneumoniae cannot be reliably differentiated by clinical signs or symptoms.
  
  
  OBJECTIVE
  To find differences in the roentgenographic patterns of community-acquired pneumonia caused by C pneumoniae, S pneumoniae, or both in hospitalized patients during a C pneumoniae epidemic in Finland.
  
  
  METHODS
  The patients were divided into 3 groups: 24 patients with serologic evidence of C pneumoniae only; 8 patients with combined C pneumoniae and S pneumoniae infection; and 13 patients with infection caused by S pneumoniae only. The chest roentgenograms obtained on admission to the hospital, during the hospital stay, and at follow-up visits were reevaluated by one of us (S.L.) who was unaware of the causative organism. In the final study groups, other causes of community-acquired pneumonia were excluded by a large pattern of microbiological methods.
  
  
  RESULTS
  Bronchopneumonia was observed in 21 (88%) of the group with C pneumoniae and 10 (77%) of the group with S pneumoniae (P = .67). Lobar or sublobar (air space) pneumonia was seen in 7 (29%) of the patients with C pneumoniae compared with 7 (54%) with pneumonia caused by S pneumoniae. In the combined group, bronchopneumonia was seen as frequently as in the group with C pneumoniae, and air-space involvement was seen as frequently as in the group with S pneumoniae. The pneumonic shadowing was usually unilateral and in the lower lobes in all groups. Of the patients in the C pneumoniae group, 17% had residual abnormalities at follow-up visits.
  
  
  CONCLUSIONS
  Roentgenographic changes cannot be used to differentiate pneumonia caused by C pneumoniae from that caused by S pneumoniae. Thus, initial antibiotic treatment should be directed at the pathogens that commonly cause community-acquired pneumonia.
authors.affiliation: National Public Health Institute, Oulu, Finland.
authors.forename: M T
authors.initials: MT
authors.lastname: Kauppinen
authors.forename: S
authors.initials: S
authors.lastname: Lähde
authors.forename: H
authors.initials: H
authors.lastname: Syrjälä
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002690:Chlamydia Infections / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000382:microbiology*; D016993:Chlamydophila pneumoniae; D017714:Community-Acquired Infections / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D005387:Finland / Q000453:epidemiology; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000382:microbiology*; D018410:Pneumonia, Bacterial / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000382:microbiology*; D011859:Radiography