Atypical pneumonia: MedlinePlus Medical Encyclopedia

Atypical pneumonia: MedlinePlus Medical Encyclopedia

Atypical pneumonia

    

Pneumonia is inflamed or swollen lung tissue due to infection with a germ.

With atypical pneumonia, the infection is caused by different bacteria than the more common ones that cause pneumonia. Atypical pneumonia also tends to have milder symptoms than typical pneumonia.

Causes

Bacteria that cause atypical pneumonia include:

• Mycoplasma pneumonia is caused by the bacteria Mycoplasma pneumoniae. It often affects people younger than age 40.
• Pneumonia due to Chlamydophila pneumoniae bacteria occurs year round.
• Pneumonia due to Legionella pneumophila bacteria is seen more often in middle-aged and older adults, smokers, and those with chronic illnesses or a weak immune system. It can be more severe. This type of pneumonia is also called Legionnaire disease.