Ventilator-associated Pneumonia

Pneumonia developing more than 48 hours after endotracheal intubation and mechanical ventilation, a subset of hospital-acquired pneumonia with its own specific epidemiology given the direct bypass of upper airway defenses and biofilm formation on the endotracheal tube.

Early-onset (within 4 days of intubation) tends to involve more antibiotic-sensitive organisms; late-onset (5 days or more) carries a higher likelihood of multidrug-resistant organisms (Pseudomonas aeruginosa, MRSA, Acinetobacter, ESBL-producing Enterobacteriaceae).

New or worsening infiltrate on chest imaging combined with at least two of: fever, leukocytosis or leukopenia, purulent tracheal secretions, and worsening oxygenation or increased ventilatory requirement.

Clinical diagnosis is notoriously imprecise given overlap with atelectasis, pulmonary edema, and ARDS, all common in the same ventilated population.

• CXR (though limited specificity in this population)
• Respiratory sample for microbiology before starting or changing antibiotics: endotracheal aspirate (less invasive, widely used) or bronchoalveolar lavage/protected specimen brush (more specific, quantitative culture thresholds used to distinguish colonization from true infection where available)
• Blood cultures, though frequently negative even with confirmed VAP

• Empirical antibiotics guided by risk of multidrug resistance and local resistance patterns, started promptly once samples are taken
• Early-onset, no MDR risk factors: a single agent such as ceftriaxone, or a fluoroquinolone
• Late-onset or MDR risk factors (prior antibiotic use within 90 days, prolonged hospitalization, high local resistance prevalence, immunosuppression): broad combination cover, typically an antipseudomonal beta-lactam (piperacillin-tazobactam, cefepime, or a carbapenem) plus an additional antipseudomonal agent (aminoglycoside or antipseudomonal fluoroquinolone) plus MRSA cover (vancomycin or linezolid) where risk factors are present
• De-escalate to the narrowest effective regimen once culture results are available
• Standard duration 7 days for most cases responding well, per current evidence favoring shorter courses over historically longer regimens, extended for non-fermenting gram negatives (Pseudomonas, Acinetobacter) or slow clinical response
• Prevention bundle: head-of-bed elevation 30 to 45 degrees, daily sedation interruption and extubation readiness assessment, subglottic secretion drainage endotracheal tubes, oral hygiene with chlorhexidine, and minimizing unnecessary ventilator days

Referral: infectious disease/microbiology for MDR organisms or treatment failure.