Aetiology of community-acquired pneumonia in Europe by treatment setting2 5 10–53 55
| Pathogen | Percentage means | ||
| Outpatient | Hospital | Intensive care unit | |
| S pneumoniae | 38 | 27 | 28 |
| M pneumoniae | 8 | 5 | 2 |
| H influenzae | 13 | 6 | 7 |
| Chlamydophila pneumoniae | 21 | 11 | 4 |
| Staphylococcus aureus | 1.5 | 3 | 9 |
| Enterobacteriaceae | 0 | 4 | 9 |
| Pseudomonas aeruginosa | 1 | 3 | 4 |
| Legionella spp. | 0 | 5 | 12 |
| C burnetii | 1 | 4 | 7 |
| Respiratory viruses | 17 | 12 | 3 |
| Unclear | 50 | 41 | 45 |