Summary

• Community-acquired and often seen in young adults living in close proximity.
• Atypical bacterial pneumonia is most commonly caused by Mycoplasma pneumoniae, Chlamydophila pneumoniae, or Legionella pneumophila.
• Usually presents with a low-grade fever, persistent dry cough, and constitutional symptoms, for example, malaise.
• Diagnosis is mostly clinical. Molecular-based diagnosis (e.g., PCR) of throat swabs or sputum can be performed. Serology can be used to confirm the diagnosis. For L pneumophila, special tests for serotype 1 (80% of cases) are available.
• Treatment is often outpatient based with a macrolide or doxycycline.
• Extrapulmonary manifestations may occur, especially in M pneumoniae infections.