17th February 2025

Overview of bacterial respiratory infections

Bacterial pathogens constitute a majority of respiratory infections that require medical intervention and treatment. The different bacterial pathogens often result in specific clinical courses. 

The vast majority of community-acquired pneumonia is caused by Streptococcus pneumoniae and Haemophilus influenzae. Atypical pneumonia is caused by pathogens that may be harder to detect, such as Legionella, Mycoplasma or Chlamydia, and are associated with specific causes. Hospital-acquired pneumonia is defined as pneumonia starting from 72 hours after admission to hospital and is very often bacterial. Hospital-acquired pneumonia is associated with a worse outcome than community-acquired pneumonia. Ventilator-acquired pneumonia is common in patients who are on ventilators for longer than 72 hours; this carries a poor prognosis.