How Pneumonia Develops
Pneumonia usually occurs when a person's defense system has been weakened by another illness, typically a viral upper respiratory tract infection or influenza (flu). Although these respiratory infections do not directly cause pneumonia, they are able to disrupt the protective coating of mucus in the lungs, thus encouraging bacterial growth.
Types of Pneumonia
Pneumonia is defined by its location. Lobar pneumonia occurs in one lobe or part of a lung, while bronchopneumonia is a patchy infection occurring throughout the lungs.
Pneumonia is also defined by how is was acquired and its severity.
Classification of Pneumonia
There are two classifications or categories of pneumonia which are defined by where the pneumonia was contracted.
Community-Acquired Pneumonia (CAP)
This category of pneumonia is contracted within the community (outside a hospital setting). It is the most common pneumonia, affecting nearly four million adults each year. Community-Acquired pneumonia typically follows a respiratory infection, however it is most often caused by Streptococcus pneumoniae.
Hospital-Acquired Pneumonia (HAP)
This category of pneumonia is contracted within a hospital setting and is also called nosocomial pneumonia. Hospital patients are particularly vulnerable to gram-negative bacteria and staphylococci.
How Pneumonia Infects the Lungs
What is the difference between pneumonia and bronchitis?
Source: A.D.A.M.
Updated: 12/14/05
