Society Guidelines for Ventilator-Associated Pneumonia (VAP) Management
Empiric Antibiotic Selection Based on Risk Stratification
The 2016 IDSA/ATS guidelines recommend that empiric therapy for VAP must cover Staphylococcus aureus, Pseudomonas aeruginosa, and other gram-negative bacilli, with regimen selection determined by multidrug-resistant (MDR) pathogen risk factors and local antibiograms 1.
Risk Factors for MDR Pathogens
Patients require broad-spectrum coverage if they have any of the following 2:
- Prior intravenous antibiotic use within 90 days
- Septic shock at time of VAP diagnosis
- ARDS preceding VAP
- Five or more days of hospitalization prior to VAP
- Acute renal replacement therapy prior to VAP onset
Low-Risk Patients (No MDR Risk Factors)
For patients without MDR risk factors in units with low MRSA prevalence, use single-agent therapy with one of the following 2, 3:
- Piperacillin-tazobactam
- Cefepime
- Levofloxacin
- Imipenem
- Meropenem
Empiric Coverage for High-Risk Patients
MRSA Coverage
Use vancomycin or linezolid for empiric MRSA coverage 2, 3. However, avoid vancomycin as first-line therapy if MSSA is confirmed, as oxacillin, nafcillin, or cefazolin are preferred for susceptible strains 3.
Pseudomonas aeruginosa Coverage
For patients with MDR Pseudomonas risk factors, use two antipseudomonal agents from different classes 1, 2. Never use aminoglycosides as monotherapy 1, 2, 3.
Acceptable combinations include 1:
- Beta-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS
- Aminoglycoside OR fluoroquinolone
Definitive Therapy Based on Culture Results
Pseudomonas aeruginosa
**Once susceptibilities are known, use monotherapy for patients not in septic shock or at high risk of death (mortality risk <15%)** 1. For patients remaining in septic shock or at high mortality risk (>25%) when susceptibilities return, continue combination therapy with two agents to which the isolate is susceptible 1.
ESBL-Producing Gram-Negative Bacilli
Base definitive therapy on antimicrobial susceptibility testing and patient-specific factors (allergies, comorbidities) 1.
Acinetobacter Species
- If susceptible: Use carbapenem or ampicillin-sulbactam 1
- If sensitive only to polymyxins: Use intravenous polymyxin (colistin or polymyxin B) plus adjunctive inhaled colistin 1
- Do not use tigecycline 1
- Do not add rifampicin to colistin 1
Carbapenem-Resistant Pathogens
Use intravenous polymyxins (colistin or polymyxin B) plus adjunctive inhaled colistin 1. Administer inhaled colistin promptly after mixing with sterile water per FDA safety recommendations 1.
Duration of Therapy
Treat VAP for 7 days rather than longer durations 1. This applies to HAP as well 1. Adjust duration based on clinical, radiologic, and laboratory improvement 1.
If using aminoglycoside combination therapy, discontinue the aminoglycoside after 5-7 days in responding patients 1.
De-escalation Strategy
De-escalate from empiric broad-spectrum therapy to narrower coverage based on culture results at 48-72 hours 1, 2, 3. This means:
- Changing to a narrower-spectrum agent
- Switching from combination to monotherapy
- Discontinuing antibiotics entirely if VAP is unlikely
Consider using procalcitonin levels plus clinical criteria to guide discontinuation decisions 1. Do not use the Clinical Pulmonary Infection Score (CPIS) alone for this purpose 1.
Diagnostic Approach
Obtain quantitative cultures via fiberoptic bronchoscopy before starting antibiotics, but do not delay treatment 2. Use direct staining to help target initial therapy 2.
Do not treat Candida species colonization in respiratory samples with antifungal therapy 2.
Critical Pitfalls to Avoid
- Never delay antibiotic initiation while awaiting diagnostic results 2, 3
- Never use aminoglycosides as monotherapy 1, 2, 3
- Never continue unnecessarily broad therapy after culture results demonstrate a susceptible organism 2, 3
- Never ignore local resistance patterns when selecting empiric therapy 2, 3
- Never use vancomycin for confirmed MSSA when narrower agents are available 2, 3