Pneumonia

Pneumonia
An infection of the lung parenchyma. Incidence of community-acquired pneumonia is 12 per 1000 adults.
Of these, 1 will require hospitalization, and mortality in these patients is still 10%.

Common organisms
Streptococcus pneumoniae is the commonest cause (60-75%).
Mycoplasma pneumoniae (5-18%).
Staphylococcus aureus.
Haemophilus influenzae.
Legionella species and Chlamydia psittaci.
Gram-negative bacilli, often hospital-acquired or immunocompromised, eg Pseudomonas especially in those with COPD.
Viruses including influenza account for up to 15%.

Symptoms
Fever, rigors, malaise, anorexia, dyspnoea, cough, purulent sputum (classically "rusty" with pneumococcus), haemoptysis, and pleuritic chest pain.

Signs
Fever, cyanosis,
herpes labialis (pneumococcus), confusion,
tachypnoea, tachycardia, hypotension,
signs of consolidation (diminished expansion, dull percussion note, increased tactile vocal fremitus/vocal resonance, bronchial breathing),
and a pleural rub.