Acute Alveolar Pneumonia: Definition and Pathophysiology

Acute alveolar pneumonia (synonymous with lobar pneumonia or pneumococcal pneumonia) is an acute infection of the pulmonary alveoli causing consolidation and loss of aeration.

Pathogenesis

1. Pathogen (often Streptococcus pneumoniae) reaches alveoli.
2. Inflammatory exudate (fibrin, neutrophils, RBCs) fills alveolar spaces.
3. Consolidation → air bronchograms on imaging.

Classic Features

• Abrupt fever, rigors, pleuritic chest pain.
• Rust‑colored sputum.
• Bronchial breath sounds, crackles, increased tactile fremitus over consolidation.

Treatment

Empiric antibiotics per local guidelines (e.g., beta‑lactam ± macrolide/fluoroquinolone); supportive care.