Pneumonia is infection of the lungs' parenchima. Pneumonia can be often present together with infection of the bronchi (bronchitis) as bronchopneumonia.
Pneumonia is classified in 3 big categories:
1. community acquired pneumonia (CAP) which is subdivided to typical and atypical pneumonia;
2. Pneumonias in immuno compromised patients, and
3. Nosocomial (intrahospital) pneumonia.
Each type of pneumonia has its own clinical, epidemiological, therapeutic and prognostic characteristics.