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