Snapshot A 77-year-old man is brought in by EMS after waking up in the middle of the night covered in sweat, with a high fever, and a coughing up yellow sputum. A chest xray is shown. Introduction Definition infection of lung parenchyma that usually occurs in defined lobar patterns, though may also present more diffusely Clinically defined as fever, cough and new infiltrate on CXR Pathophysiology See Microbiology of Pneumonia topic Risk factors impaired cough reflex damage to respiratory cilia mucus plugs Classification Classic patterns include lobar intra-alveolar exudate which consolidates may involve entire lung or be confined to 1 lobe 4 stages brochopnuemonia acute inflammatory infiltrates from bronchioles into adjacent alveoli patchy distribution involves ≥ 1 lobes interstitial diffuse patchy inflammation localized to interstitial areas of alveolar walls distribution involving ≥ 1 lobes generally less severe than lobar or bronchopneumonia Presentation Symptoms classically presents with sudden-onset of fever productive cough purulent yellow-green hemoptysis dyspnea night sweats pleuritic chest pain atypical presentations are gradual in onset and flu-like dry cough headaches myalgias sore throat Physical exam auscultation of the lungs reveals decreased or bronchial breath sounds crackles/rales wheezing E-to-A egophany with consolidation percussion reveals dullness over affected lobe(s) tactile fremitus increased with consolidation decreased with pleural effusion Evaluation CXR may show lung opacification/consolidation in affected lobe(s) establishes diagnosis in combination with Gram stain or culture CBC elevated WBC count Sputum Gram stain and cultures identify pathogen directs antimicrobial therapy Treatment Pharmacologic empiric antibiotics directed at most likely pathogens (depends on clinical scenario) organism-specific antibiotics if organism identified