<i>Mycoplasma pneumoniae</i>

Mycoplasma pneumoniae is a cause of atypical pneumonia which 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 pneumonias as they 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
• 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

Management

• erythromycin/clarithromycin
• tetracyclines such as doxycycline are an alternative