• See Also
  1. Bacterial Pneumonia
  2. Mycoplasma
  • Epidemiology
  1. Affects children (over age 3 years) and young adults
    1. Causes up to 40% of Community Acquired Pneumonia cases (esp. children age >5 years, young adults)
    2. May also be seen in the elderly
  • Pathophysiology
  1. Mycoplasma pneumoniae
    1. Mycoplasma are tiny, pleumorphic (may be cocci or rods) and lack a cell wall (gram neutral)
    2. Adhesin Virulence Protein P1
      1. Allows for Bacterial attachment to respiratory epithelium
  2. Results in respiratory infections
    1. Atypical Pneumonia (3-10% of infected patients)
      1. Interstitial infection of lung parenchyma
      2. Incubation Period: 2-3 weeks after infection
    2. Acute Tracheobronchitis
    3. Upper Respiratory Infection
  • Symptoms
  1. Slow, gradual onset of prodromal symptoms
    1. Malaise
    2. Headache
    3. Fever
      1. Usually present longer than 3 days at presentation
  2. Cough
    1. Constant, harsh, dry, hacking non-productive cough
  3. Upper respiratory symptoms (50%)
    1. Pharyngitis
    2. Ear Pain
  4. Accompanying symptoms
    1. Rash
    2. Arthralgias
  • Signs
  1. Minimal signs
    1. Mild Pneumonia more consistent with Viral Pneumonia
  2. Chest auscultation
    1. Scattered rhonchi
    2. Localized rales
  3. Serous Otitis Media
  4. Wheezing may be present
    1. Usually absent in other Bacterial Pneumonia
    2. Wheezing otherwise more common with Viral Pneumonia
  • Differential Diagnosis
  1. See Pneumonia Causes
  2. Viral Pneumonia (e.g. Adenovirus)
  3. Bacterial Pneumonia associated with other atypical Bacteria (Atypical Pneumonia)
    1. Chlamydia pneumoniae
    2. Legionella pneumonia
  1. Fine patchy interstitial or perihilar infiltrates
  2. Lower lobe more commonly affected
  • Labs
  1. Complete Blood Count
    1. WBC Count mildly elevated (10,000 to 15,000)
  2. Mycoplasma DNA PCR
    1. Modern approach to organism identification
  3. Cold Agglutinins
    1. Based on monoclonal IgM development to RBC i Antigen
      1. RBCs agglutinate (clump) at 4C when i Antigen IgM is present (in a non-clotting tube)
      2. RBCs will unclump on rewarming
    2. Nonspecific and Not sensitive (False Negative in 33% of cases)
      1. I Antigen IgM develops over the first 2 weeks of infection, peaks week 3, declines over months
  4. Mycoplasma complement fixation titers
    1. Mycoplasma GlycolipidAntigens are combined with patient blood to obtain Antibody titers
    2. Obtain acute and convalescent titers
  5. Sputum Culture
    1. Grown on media rich in Cholesterol and Nucleic Acids
    2. Form dome-shaped (fried-egg shaped) colonies after 2-3 weeks of growth
  1. See Community Acquired Pneumonia Management
  2. Dosing is listed for adults (see specific agents for pediatric dosing)
  3. Doxycycline
    1. Avoid in age <8 years or pregnancy
    2. Dosing: 100 mg orally or IV twice daily for 7-10 days
  4. Alternatives: Macrolides (increasing resistance)
    1. Azithromycin (Zithromax) 500 mg orally on day 1, then 250 mg orally on days 2-5 years
    2. Erythromycin
    3. Clarithromycin (Biaxin)
  5. Alternatives: Fluoroquinolones
    1. Levofloxacin 750 mg orally or IV for 5 days
  • Complications
  1. Complications are uncommon
  2. Mortality rate: 1.4%
  3. Pulmonary
    1. Pleural Effusion
    2. Empyema
    3. Respiratory distress syndrome
  4. Dermatologic
    1. Erythema Multiforme (up to 7% of patients)
    2. Erythema Nodosum
    3. Urticaria
  5. Neurologic
    1. Aseptic Meningitis
    2. Encephalitis
    3. Guillain-Barre Syndrome
    4. Transverse Myelitis
  6. Cardiovascular
    1. Myocarditis
    2. Pancreatitis
    3. Pericarditis
  7. Miscellaneous
    1. Hemolytic Anemia
    2. Polyarthritis
  • References
  1. (2025) Sanford Guide, accessed on IOS 3/12/2025
  2. File (1998) Infect Dis Clin North Am 12(3):569-92 [PubMed]
  3. O'Handley (1997) J Am Board Fam Pract 10(6):425-9 [PubMed]
  4. Plouffe (2000) Clin Infect Dis 31:S35-9 [PubMed]
  5. Tan (1999) Can Respir J 6:15A-9A [PubMed]
  6. Waites (2017) Clin Microbiol Rev 30(3):747-809 +PMID: 28539503 [PubMed]