What causes Atypical pneumonia?
Mycoplasma pneumonia is a type of atypical pneumonia. It is caused by the bacteria M. pneumoniae. It typically affects people younger than age 40. Pneumonia due to chlamydia-related bacteria occurs year round and accounts for 5 - 15% of all pneumonias. It is usually mild. Pneumonia due to Legionella is seen more often in middle-aged and older adults, smokers, and those with chronic illnesses or a weak immune system. </s>