28th July 2023

Atypical pneumonia

There are some important so-called ‘atypical’ causes of pneumonia. These may cause a different clinical syndrome or not respond to initial antibiotic treatment. These include:

• Mycoplasma pneumoniae characteristically causes bilateral pneumonia and is associated with neurological and dermatological complications.
• Legionella pneumophila, a spirochete found in water coolant systems such as air conditioners, is often associated with travel to hot countries. Legionnaires’ disease can cause transaminitis, hyponatremia and neurological features. It is difficult to diagnose as it does not grow on standard cultures; if suspected, urinary antigens should be tested as these are the most reliable investigation.
• Chlamydophila psittaci, a rare pathogen transmitted from close contact with birds, typically causing myalgia, headache and a dry cough.