Community-acquired pneumonia: radiographic shadowing, multilobe disease and radiographic deterioration were not very helpful in differential diagnosis.

Clinical bottom line (level 4)

  1. In patients with pneumonia or legionnaires' disease, homogeneous radiographic shadowing did not help to differentially diagnose.
  2. in patients with legionnaires' disease or pneumonia, multilobe disease did not help to differentially diagnose.
  3. Radiographic deterioration may help to differentiate between legionnaires' or bacteraemic pneumococcal pneumonia and other pneumonias.
  4. Presence of lymphadenography may help to identify mycoplasma pneumonia.
MacFarlane et al: Thorax 1984; 39: 28-33
Expires March 2003

The study

Setting: general hospital, UK

196 patients (aged range 10 to 79 years; mean 47, ?% male) community-acquired legionnaires' disease (49 patients), pneumococcal pneumonia (91), mycoplasma pneumonia (46)or psittacosis pneumonia (10)

Independent ?blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • Serology and culture of lung or respiratory secretions for legionnaires' disease or mycoplasma pneumonia. Pneumococcal pneumonia diagnosed with culture of S. pneumoniae of blood, pleural fluid or lung and/or detection of pneumococcal polysaccharide capsular antigen in serum, urine, sputum, pleural fluid or lung by countercurrent immunoelectrophoresis
Diagnostic test: radiographs reviewed systematically by two observers
  • At least one of two observers who reviewed the radiographs was blinded to the cause of pneumonia.

The evidence


differential diagnosis number of patients prevalence
(95% CI)
homogeneous radiographic shadowing in legionnaires' disease 40 81.6%
(70.8% to 92.5%)
shadowing in bacteraemic pneumococcalpneumococcal pneumonia 25 80.7%
(66.7% to 94.6%)
shadowing in nonbacteraemic pneumococcal pneumonia 42 70.0%
(58.4% to 81.6%)
shadowing in mycoplasma pneumonia 23 50.0%
(35.6% to 64.5%)
shadowing in psittacosis 6 60.0%
(29.6% to 90.4%)
multilobe disease in legionnaires' disease 19 38.8%
(25.1% to 52.4%)
multilobe disease bacteraemic pneumococcal pneumonia 20 64.5%
(47.7% to 81.4%)
multilobe disease nonbacteraemic pneumococcal pneumonia 15 25.0%
(14.0% to 36.0%)
radiographic deterioration in legionnaires' disease 30 65.2%
(51.5% to 79.0%)
radiographic deterioration in bacteraemic pneumococcal pneumonia 14 51.9%
(33.0% to 70.7%)
radiographic deterioration in nonbacteraemic pneumococcal pneumonia 15 26.3%
(14.9% to 37.8%)
radiographic deterioration in mycoplasma pneumonia 11 25.0%
(12.2% to 37.8%)
lymphadenopathy in mycoplasma pneumonia 10 21.7%
(9.82% to 33.7%)

  • Lympahdenopathy was only present in mycoplasma pneumonia.

Comments

  1. We should combine clinical features , clinical settings , microbiologic diagnosis and radiographic findings to raise the diagnostic accuracy. This study does not help specifically with this issue.

Citation

  1. MacFarlane JT, Miller AC, Smith WHR, et al: Comparative radiographic features of community-acquired legionnaires' disease, pneumococcal pneumonia, mycoplasma pneumonia, and psittacosis. Thorax 1984; 39: 28-33
Contributor: Clare Wotton and Musab Hayatli, November 1999
Reviewer: Mitsuhiro Kamei

Clinical Question.
Patient community-acquired legionnaires' disease or pneumonia
Intervention or Exposure radiographic data
Comparison serological data
Outcome diagnosis