Mycoplasma pneumonia (also known as "walking pneumonia" because its patients can sometimes continue to walk about while suffering from its symptoms) is a form of bacterial pneumonia caused by the bacterial species Mycoplasma pneumoniae.
Mycoplasma pneumoniae is spread through respiratory droplet transmission. Once attached to the mucosa of a host organism, M. pneumoniae extracts nutrients, grows, and reproduces by binary fission. Attachment sites include the upper and lower respiratory tract, causing pharyngitis, bronchitis, and pneumonia. The infection caused by this bacterium is called atypical pneumonia because of its protracted course and lack of sputum production and wealth of extrapulmonary symptoms. Chronic Mycoplasma infections have been implicated in the pathogenesis of rheumatoid arthritis and other rheumatological diseases.
M. pneumoniae infections can be differentiated from other types of pneumonia by the relatively slow progression of symptoms. A positive blood test for cold-hemagglutinins in 50-70% of patients after 10 days of infection (cold-hemagglutinin-test should be used with caution or not at all, since 50% of the tests are false-positive), lack of bacteria in a Gram-stained sputum sample, and a lack of growth on blood agar.
While antibiotics with activity specifically against M. pneumoniae are often used (e.g., erythromycin), doxycycline, it is unclear if these result in greater benefit than using antibiotics without specific activity against this organism in those with an infection acquired in the community.