<i>Mycoplasma pneumoniae</i>

Mycoplasma pneumoniae

Mycoplasma pneumoniae is a cause of atypical pneumonia

atypical pneumonia

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that often affects younger patients. It is associated with a number of characteristic complications such as erythema multiforme and cold autoimmune haemolytic anaemia. Epidemics of Mycoplasma pneumoniae classically occur every 4 years. It is important to recognise atypical pneumonia as it may not respond to penicillins or cephalosporins due to it lacking a peptidoglycan cell wall.

Features

Stereotypical history of mycoplasma pneumonia: worsening flu-like symptoms and a dry cough. Erythema multiforme is noted on examination

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Importance: 40

• the disease typically has a prolonged and gradual onset
• flu-like symptoms classically precede a dry cough
• bilateral consolidation on x-ray
• complications may occur as below

Complications

• cold agglutins (IgM)
  Mycoplasma pneumoniae - cold agglutins (IgM)
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  Importance: 44
  : may cause an haemolytic anaemia
  Mycoplasma pneumoniae patient with anaemia, raised LDH, raised unconjugated bilirubin --> autoimmune haemolytic anaemia
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  Importance: 45
  , thrombocytopenia
• erythema multiforme
  Mycoplasma is associated with erythema multiforme
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  Importance: 62
  , erythema nodosum
• meningoencephalitis, Guillain-Barre syndrome and other immune-mediated neurological diseases
  immune-mediated neurological diseases
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• bullous myringitis
  Mycoplasma pneumoniae - bullous myringitis
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  Importance: 24
  : painful vesicles on the tympanic membrane
• pericarditis/myocarditis
• gastrointestinal: hepatitis, pancreatitis
• renal: acute glomerulonephritis

Investigations

• diagnosis is generally by Mycoplasma serology
  Mycoplasma? - serology is diagnostic
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  Importance: 83
• positive cold agglutination test
  Mycoplasma pneumoniae - may cause a positive cold agglutination test
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  Importance: 11
  → peripheral blood smear may show red blood cell agglutination
  Pneumonia, peripheral blood smear showing red blood cell agglutination --> Mycoplasma pneumoniae
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  Importance: 90

Management

• doxycycline or a macrolide
  Mycoplasma pneumonia - treat with doxycycline or a macrolide
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  Importance: 94
  (e.g. erythromycin/clarithromycin)

+PassMedicine Notes

Mycoplasma pneumoniae is a cause of atypical pneumonia that often affects younger patients. It is associated with a number of characteristic complications such as erythema multiforme and cold autoimmune haemolytic anaemia. Epidemics of Mycoplasma pneumoniae classically occur every 4 years. It is important to recognise atypical pneumonia as it may not respond to penicillins or cephalosporins due to it lacking a peptidoglycan cell wall.

Features

• the disease typically has a prolonged and gradual onset
• flu-like symptoms classically precede a dry cough
• bilateral consolidation on x-ray
• complications may occur as below

Complications

• cold agglutins (IgM): may cause an haemolytic anaemia, thrombocytopenia
• erythema multiforme, erythema nodosum
• meningoencephalitis, Guillain-Barre syndrome and other immune-mediated neurological diseases
• bullous myringitis: painful vesicles on the tympanic membrane
• pericarditis/myocarditis
• gastrointestinal: hepatitis, pancreatitis
• renal: acute glomerulonephritis

Investigations

• diagnosis is generally by Mycoplasma serology
• positive cold agglutination test --> peripheral blood smear may show red blood cell agglutination

Management

• doxycycline or a macrolide (e.g. erythromycin/clarithromycin)

pdd903.png Comparison of Legionella and Mycoplasma pneumonia