- 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)
- Infection may be asymptomatic, most often confined to the upper respiratory tract; however, may progress to pneumonia (5–10%)
- Course is usually acute with an incubation period of 1 to 4 weeks (1).
- Synonym(s): primary atypical pneumonia (PAP); Eaton agent pneumonia; cold agglutinin–positive pneumonia; walking pneumonia
- Increased incidence of asthma exacerbation in older children
- Infants 3 to 6 months old with suspected bacterial pneumonia should be hospitalized.
- ~1 million cases/year and an annual infection rate of 1% in the United States
- 20% of community-acquired pneumonia (CAP) require hospitalizations annually.
- Most frequently in fall/winter seasons
- 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.
- 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.
- Immunocompromised state (e.g., HIV, transplant recipients, chemotherapy)
- Close community 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
There's more to see -- the rest of this topic is available only to subscribers.