Ventilator-associated pneumonia
Formal Definition
Pneumonia developing >48 hours after endotracheal intubation and mechanical ventilation; the most common ICU-acquired infection with mortality of 20-50%; risk increases with duration of mechanical ventilation, reintubation, and prior antibiotic exposure; early-onset VAP (within 5 days of intubation) typically involves more antibiotic-susceptible organisms (S. pneumoniae, H. influenzae, MSSA), while late-onset VAP (>5 days) more commonly involves MDR pathogens (Pseudomonas, Acinetobacter, MRSA).
How It's Used on the Ward
"VAP" — the patient was intubated for something else and now has a new lung infection because the breathing tube bypassed the normal defenses; the longer the tube stays in, the higher the risk; diagnosis is tricky because the patient is already sick and on antibiotics; prevention is the name of the game: head of bed elevation, daily sedation vacation, oral chlorhexidine.
Example
""58-year-old male intubated 9 days ago for ARDS from pneumonia. Now has new fevers (39.2°C), increased purulent sputum from the endotracheal tube, increased oxygen requirements (FiO2 60% from 40%). CXR: new bilateral infiltrates. Tracheal aspirate culture: Pseudomonas aeruginosa resistant to ceftazidime and ciprofloxacin, sensitive to piperacillin-tazobactam and meropenem. Diagnosis: late-onset ventilator-associated pneumonia (VAP) with MDR Pseudomonas. Empiric meropenem started pending sensitivities, de-escalated to piperacillin-tazobactam once susceptibilities confirmed. Sedation vacation attempted, goal of decreasing days on ventilator.""
Clinical Context
Diagnosis: Clinical (fever + purulent secretions + new/increasing infiltrate) + bronchoscopy/BAL (quantitative cultures, threshold 10^4 CFU/mL for protected brush, 10^5 for BAL). Avoids overtreatment for colonization. Prevention bundle (IHI/VAP bundle): head of bed 30-45 degrees, daily sedation vacation + spontaneous breathing trial, oral chlorhexidine, peptic ulcer prophylaxis, DVT prophylaxis. Empiric antibiotics must cover Pseudomonas and MRSA for late-onset VAP: antipseudomonal beta-lactam (cefepime, piperacillin-tazobactam, meropenem) + MRSA coverage (vancomycin or linezolid) + consider double coverage with aminoglycoside/fluoroquinolone if high-risk. De-escalate based on culture results. Duration: 7-8 days for most VAP; 14 days for non-fermenting Gram-negatives (Pseudomonas, Acinetobacter). Resistant organisms: Pseudomonas, Acinetobacter, MRSA — higher mortality, consider inhaled antibiotics (colistin, tobramycin) as adjunct.