Pneumonia, Mycoplasma
Basics
Description
- Bronchopulmonary infection caused by one of several Mycoplasma spp.; Mycoplasma pneumoniae being the most common pathogen of the class
- Smallest, free-living organism; fastidious and slow-growing; first isolated in cattle in 1898
- Most frequently affects children/young adults but can also occur in the elderly; often causes epidemics in close communities (i.e., skilled nursing facilities, dormitories, military barracks)
- Infection may be asymptomatic, most often confined to the upper respiratory tract; however, may progress to pneumonia (5–10%) (1)
- Course is usually acute with an incubation period of 1 to 4 weeks.
- Synonym(s): primary atypical pneumonia (PAP); Eaton agent pneumonia; cold agglutinin–positive pneumonia; walking pneumonia
Pediatric Considerations
- Increased incidence of asthma exacerbation in older children
- Infants 3 to 6 months old with suspected bacterial pneumonia should be hospitalized.
Epidemiology
Incidence
- ~1 million cases/year in United States; annual infection rate of 1% in United States
- 20% of CAP requiring hospitalizations annually
- Most frequently in autumn/winter seasons
Prevalence
- Predominant sex: male = female
- Predominant age group affected: 5 to 20 years
- May occur at any age
- Rare in children <5 years of age
- Responsible for up to 15–20% of all cases of CAP yearly
- Most common cause of pneumonia in school children and young adults who do not have a chronic underlying condition
Etiology and Pathophysiology
- M. pneumoniae is a short-rod mucosal pathogen, which lacks a cell wall and thus not visible on Gram stain.
- Can grow under both aerobic and anaerobic conditions
- Highly contagious, transmitted by aerosol droplets
- Pathogenicity linked to its filamentous tips, which adhere selectively to respiratory epithelial cell membrane proteins with production of H2O2 and superoxide radicals, damaging cilia
- Decreased ciliary movement produces prolonged paroxysmal, hacking cough.
- Incubation period is 2 to 3 weeks.
ALERT
- M. pneumoniae infection may worsen asthma symptoms as well as cause wheezing in children without asthma.
- M. pneumoniae infection may worsen chronic obstructive pulmonary disease (COPD) or other chronic pulmonary condition symptoms in adults.
Risk Factors
- Immunocompromised state (e.g., HIV, transplant recipients, chemotherapy)
- Smoking
- Close communal living (e.g., military barracks, prisons, hospitals, dormitories, schools, household contacts, skilled nursing facilities)
Commonly Associated Conditions
- Asthma exacerbations as a result of proinflammatory cytokine release
- COPD
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Citation
Domino, Frank J., et al., editors. "Pneumonia, Mycoplasma." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116466/2.2/Pneumonia_Mycoplasma.
Pneumonia, Mycoplasma. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116466/2.2/Pneumonia_Mycoplasma. Accessed December 3, 2024.
Pneumonia, Mycoplasma. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116466/2.2/Pneumonia_Mycoplasma
Pneumonia, Mycoplasma [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 December 03]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116466/2.2/Pneumonia_Mycoplasma.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Pneumonia, Mycoplasma
ID - 116466
ED - Domino,Frank J,
ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116466/2.2/Pneumonia_Mycoplasma
PB - Wolters Kluwer
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DB - Medicine Central
DP - Unbound Medicine
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