Mycoplasma pneumonia

Aka: Mycoplasma pneumonia, Mycoplasma pneumoniae, Walking Pneumonia

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II. Pathophysiology

  1. Interstitial infection of lung parenchyma
  2. Organism lacks a cell wall
  3. Results in respiratory infections
    1. Atypical Pneumonia (3-10% of infected patients)
    2. Acute Tracheobronchitis
    3. Upper Respiratory Infection

III. Epidemiology

  1. Affects children (over age 3 years) and young adults
    1. May also be seen in the elderly

IV. 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

V. Signs

  1. Minimal signs
  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

VI. Differential Diagnosis

  1. Viral Pneumonia (e.g. Adenovirus)
  2. Bacterial Pneumonia associated with other atypicals
    1. Chlamydia pneumoniae
    2. Legionella pneumonia

VII. Radiology: Chest XRay

  1. Fine patchy interstitial or perihilar infiltrates
  2. Lower lobe more commonly affected

VIII. Labs

  1. Complete Blood Count
    1. WBC Count mildly elevated (10,000 to 15,000)
  2. Cold Agglutinins
    1. Nonspecific
    2. Not sensitive (False Negative in 33% of cases)
  3. Mycoplasma complement fixation titers
    1. Obtain acute and convalescent titers

IX. Management: Antibiotic for 10 to 14 days

  1. Erythromycin
  2. Clarithromycin (Biaxin)
  3. Azithromycin (Zithromax)
  4. Doxycycline
    1. Avoid in age <8 years or pregnancy
    2. Dosing: 100 mg PO daily for 10 to 14 days
    3. Alternative dosing
      1. Dose twice daily for 1 day, once daily for 13 days
      2. Reduces gastrointestinal side effects

X. 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
    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

XI. References

  1. Gilbert (2001) Sanford Antimicrobial, p. 25
  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]

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