DefinitionAtypical pneumonia refers to pneumonia caused by certain bacteria, including Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae.This article provides a general overview of atypical pneumonia.See also:Legionella pneumonia (Legionnaire's disease)Mycoplasma pneumoniaAlternative NamesWalking pneumonia; Chlamydophila pneumoniaeCauses, incidence, and risk factorsAtypical pneumonia due to mycoplasma and chlamydophila bacteria usually cause mild forms of pneumonia, unlike other types of the disease that can come on more quickly with more severe early symptoms.Mycoplasma pneumonia often affects younger people and may be associated with anemia, certain types of rashes, and neurological conditions such as meningitis, myelitis, and encephalitis. For more information