USMLE Prep - Medical Reference Library

Hospital- and Ventilator-Associated Pneumonia — Adult

System: Infectious Diseases • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Diagnose with new infiltrate plus clinical criteria; start empiric therapy based on MDR risk and local antibiogram; de-escalate with cultures; typical duration ~7 days if improving.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

For Hap Vap Adult, frame the differential by acuity and pathophysiology, then align diagnostics to the leading hypotheses. Prioritize stabilization while obtaining high‑yield studies such as CBC (Inflammation/infection), Lactate (Hypoperfusion), Blood cultures (Pathogen ID). Incorporate bedside imaging and targeted labs to define severity and identify complications; synthesize results with clinical trajectory to refine the working diagnosis and disposition needs.


Treatment Strategy & Disposition

Initiate disease‑directed therapy alongside supportive care, titrating to objective response. Pharmacologic options commonly include Broad-spectrum antibiotics. Use validated frameworks (e.g., Common MDR Risk Factors) to guide escalation and site of care. Address precipitating factors, de‑escalate empiric therapies with data, and arrange follow‑up for monitoring and risk‑factor modification; admit patients with instability, high risk of deterioration, or needs for close monitoring.


Epidemiology / Risk Factors

  • Immunosuppression, devices; recent hospitalization

Investigations

TestRole / RationaleTypical FindingsNotes
CBCInflammation/infectionLeukocytosis/leukopenia
LactateHypoperfusionElevatedTrend
Blood culturesPathogen IDPositive/negativeBefore antibiotics if feasible

Common MDR Risk Factors

DomainExamples
Recent antibioticsWithin prior 90 days
Healthcare exposureResidence in units with high MRSA/Pseudomonas prevalence
Ventilation factorsLonger duration of ventilation

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Cefepime4th-gen cephalosporinHoursAnti-pseudomonal coverageNeurotoxicity (AKI)
Piperacillin-tazobactamβ-lactam/β-lactamase inhibitorHoursBroad gram-neg incl. PseudomonasAllergy, AKI
VancomycinCell-wall inhibitionHoursMRSA coverageNephrotoxicity; monitor trough/AUC
LevofloxacinFluoroquinoloneHoursAdd/alternative gram-negative/atypicalsQT, tendinopathy
De-escalation per culturesN/ADaysNarrow once ID/AST knownResistance stewardship

Prognosis / Complications

  • Depends on host and source control; sepsis/organ failure risk

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

Notes

Implement ventilator bundle (elevation, sedation minimization, oral care). Consider inhaled antibiotics only in select MDR pathogens with poor penetration.


References

  1. ATS/IDSA HAP/VAP Guidelines — Link
  2. CDC — HAI/VENT Prevention — Link