Bronchopneumonia vs Lobar Pneumonia

Types of Pneumonia

• Bronchopneumonia: affects very young, elderly, and debilitated individuals; centered on bronchioles, not restricted to a single lobe; incomplete resolution with scarring and tissue destruction; significant risk of death
• Lobar pneumonia: affects healthy individuals; typically affects a single lobe; complete resolution and tissue restoration; majority recover

Lobar Pneumonia Stages

• 1st Stage: Congestion - acute inflammatory response to an infectious organism; increased alveolar blood flow, capillary congestion, and protein-rich exudate into the alveoli
• Advanced organizing pneumonia: exudates converted to fibromyxoid masses rich in macrophages and fibroblasts
• Acute pneumonia: alveolar consolidation is absent but pink proteinaceous exudate may occur; normal architecture of the lung is preserved following resolution of infection

Healthcare-Associated Pneumonia

• Hospitalization of at least 2 days within the recent past; presentation from a nursing home or a long-term care facility; attending a hospital or hemodialysis clinic; recent IV antibiotic therapy; chemotherapy or wound care
• Most common organisms: MRSA and P. aeruginosa
• Higher mortality than community-acquired pneumonia

Hospital-Acquired Pneumonia

• Pulmonary infections acquired in the course of a hospital stay
• Common in patients with severe underlying disease, immunosuppression, prolonged antibiotic therapy, or invasive access devices
• Patients on mechanical ventilation are at high risk
• More common isolates: Gram-positive cocci (S. aureus), Gram-negative rods (Enterobacteriaceae, Pseudomonas spp)

Aspiration Pneumonia

• Occurs in markedly debilitated patients or those who aspirate gastric contents
• Seen in patients with abnormal gag and swallowing reflexes that predispose to aspiration
• Pneumonia is partly chemical and partly bacterial; culture: more than one organism is recovered; aerobes more common than anaerobes
• Pneumonia is often necrotizing, fulminant course; lung abscess is a common complication

Overview of Pneumonia

• Broadly defined as any infection of the lung parenchyma
• Classified based on etiologic agent or clinical setting in which the infection occurs
• 50% of cases: no pathogen is isolated
• Can result whenever local defense mechanisms are impaired or systemic resistance of host is impaired
• Predisposing factors of pneumonia: INSPIRATION (Immunosuppression, Neurological impairment, Secretion retention, Pulmonary edema, Impaired mucociliary clearance, Respiratory tract infection, Antibiotics and cytotoxins, Tracheal instrumentation, Impaired alveolar macrophages, Other, Neoplasia)