Table 1

Aetiology of hospitalised CAP in adults in Europe

Causative pathogenFrequency
Bacterial pathogens0–47
Streptococcus pneumoniae 11–68
Haemophilus influenzae 5.3–12.3
Legionella pneumophilia 0–12.8
Staphylococcus aureus 0–11.8
Moraxella catarrhalis 0–5.4
Gram-negative bacteria0–24.2
Mycoplasma pneumoniae 0.7–32.0
Chlamydia pneumoniae 1.0–26.5
 Influenza viruses15–19
 Respiratory syncytial virus3–4
 Bacterial–viral coinfection31
  • The main causative organisms for CAP are listed, with frequency expressed as a percentage. Relative frequencies are pooled from multiple studies; some studies did not test for certain pathogens. Adapted from Welte and Köhnlein,4 Ewig et al 9 and Holter et al.10

  • CAP, community-acquired pneumonia.