Pneumonia

Pneumonia can be due to microorganisms, irritants or unknown causes. When pneumonias are grouped this way, infectious causes are the most common.

The symptoms of infectious pneumonia are caused by the invasion of the lungs by miicroorganisme response to the infection. Although more than one hundred strains of microorganism can cause pneumonia, only a few are responsible for most cases. The most common causes of pneumonia are viruses and bacteria  Less common causes of infectious pneumonia are fungi 

Bacteria are the most common cause of community acquired pneumonia with Streptococcus.