Table 1.
Important pathogens causing pneumonia
| Pathogen | CAP | HAP/HCAP | Adults | Children |
| Bacteria | ||||
| S. pneumoniae | +++ | +++ | +++ | +++ |
| H. influenzae | ++ | ++ | ++ | ++ |
| M. pneumoniae | +++ | + | ++ | +++ |
| Chlamydia spp. | + | (+) | ++ | |
| Klebsiella spp. | + | ++ | ||
| Legionella spp. | ++ | +++ | ||
| S. aureus | ++ | +++ | +++ | + |
| P. aerugenosa | + | +++ | + | |
| Acinetobacter spp. | ++ | |||
| Viruses | ||||
| RSV | ++ | + | +++ | |
| Rhinovirus | ++ | (+) | ++ | |
| Influenza virus | ++ | + | + | ++ |
| Parainfluenza virus | ++ | + | ++ | |
| Fungi | ||||
| Candida spp. | ++1 | |||
| Aspergillus spp. | ++1 | |||
| P. jirovecii | +2 |
+ indicates the relative importance of the pathogen and the frequency of isolation in adults or children. 1 of importance in immunocompromised hosts. 2 important opportunistic pathogen in HIV/AIDS patients. CAP, community-acquired pneumonia; HAP, hospital-acquired pneumonia; HCAP, health-care associated pneumonia. Based on collective data [2,5,6,15-18,23,252,253].