Serum | Respiratory viruses | Complement fixation | Complement fixation | Acute titre ≥1/128 or four-fold rise between paired sera |
| Atypical bacteria |
| Mycoplasma | IgM antibody | IgM antibody | Positive |
| Group A Streptococcus | ASOT (IU·mL−1) | ASOT (IU·mL−1) | Acute two-fold rise or four-fold rise between paired sera |
Blood | Bacteria | Culture | Culture | Growth |
| Streptococcus pneumoniae | Real-time PCR | Real-time PCR | Positive |
Nasopharyngeal secretions/sputum | Respiratory viruses | IFAT | Real-time PCR | Positive |
| Bacteria | Culture | Culture/real-time PCR | Not applicable |
Tracheobronchial secretions (bronchoalveolar lavage/endotracheal) | Respiratory viruses | IFAT | Real-time PCR | Positive |
| Bacteria | Culture | Culture/real-time PCR | Growth/positive |
Pleural fluids | Bacteria | Culture | Culture | Growth |
| Pneumococcal antigen | ELISA | ELISA | Positive |
| Streptococcus pneumoniae | Not tested | Real-time PCR | Positive |