C-reactive protein (CRP) levels and aetiological diagnosis
| Agent | Patients n | CRP mean mg·dL−1 |
| Typical bacterial pneumonia | 141 | 16 |
| Streptococcus pneumoniae | 80 | 17.15 |
| Haemophilus influenzae | 26 | 12.93 |
| Other | 35 | 15.6 |
| Legionella pneumophila pneumonia | 30 | 25.23 |
| Atypical pneumonia | 52 | 12.64 |
| Chlamydia pneumoniae | 20 | 11.74 |
| Mycoplasma pneumoniae | 17 | 16.02 |
| Coxiella burnetii | 15 | 10.02 |
| Viral | 35 | 14.45 |
| Total | 258 | 16.18 |
| Patients with >1 pathogen identified | 80 | |
| Pyogenic pneumonia# | 38 | 18.82 |
| Pyogenic pneumonia+Legionella¶ | 2 | 14.9 |
| Pyogenic pneumonia+atypical bacteria | 12 | 13.8 |
| Pyogenic pneumonia+viral | 17 | 16.76 |
| Viral pneumonia+Legionella¶ | 1 | 33.98 |
| Viral pneumonia+atypical bacteria¶ | 6 | 12.9 |
| Atypical pneumonia+Legionella¶ | 4 | 27.03 |
| CAP of unknown aetiology | 383 | 14.01 |
CAP: community-acquired pneumonia. #: >1 microorganism isolated; ¶: not included in statistical analyses due to the small number of cases