Pulmonary · PANCE / PANRE

Hospital-Acquired and Ventilator-Associated Pneumonia (HAP/VAP)

Pneumonia developing ≥48 h after hospital admission or ≥48 h after intubation.

Also known as: HAP, VAP, nosocomial pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia

Overview

HAP: pneumonia occurring ≥48 hours after hospital admission not incubating at admission. VAP: pneumonia developing ≥48 hours after endotracheal intubation. Caused by hospital-flora organisms with frequent multidrug resistance.

Epidemiology

HAP is the second most common nosocomial infection. VAP develops in 10-20% of patients ventilated >48 h, with attributable mortality up to 13%. Resistant pathogens (MRSA, Pseudomonas, Acinetobacter, ESBL Enterobacterales) increasingly common.

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Risk factors

Mechanical ventilation (single greatest risk for VAP)
Prior IV antibiotic exposure (especially within 90 days)
Hospitalization ≥5 days, ICU stay
Aspiration risk, impaired consciousness, NG tube
Reintubation, supine positioning, inadequate cuff pressure
Immunocompromise, chronic lung disease
Recent influenza or other respiratory viral infection

Pathophysiology

Aspiration of oropharyngeal secretions colonized with hospital flora past an endotracheal tube cuff. Biofilm on the ETT serves as a reservoir. Common pathogens: Pseudomonas aeruginosa, Staphylococcus aureus (including MRSA), Klebsiella, E. coli, Enterobacter, Acinetobacter, Stenotrophomonas. Anaerobes are LESS important than previously thought.

Clinical presentation

Symptoms

New or worsening dyspnea, purulent tracheobronchial secretions
Fever, chills
Mental status change (especially in elderly)
Often subtle in ventilated/sedated patients — recognize by changes in vent parameters

Signs / physical exam

New fever or hypothermia, leukocytosis or leukopenia
Hypoxia, increasing FiO2 or PEEP requirements
Purulent endotracheal aspirate
New crackles or focal lung findings

Differential diagnosis

Atelectasis — Post-op or immobilized; rapid resolution with recruitment; no leukocytosis or fever pattern
Pulmonary embolism — Acute dyspnea/hypoxia, elevated D-dimer, CTPA; RV strain on echo
ARDS — Bilateral infiltrates within 1 week of insult, PaO2/FiO2 ≤300, no cardiac etiology
Pulmonary edema (cardiogenic or volume overload) — Bilateral, gravity-dependent, responsive to diuresis; elevated BNP, S3
Aspiration pneumonitis (chemical) — Witnessed aspiration; rapid radiographic improvement within 24-36 h without antibiotics
Drug-induced lung injury — Temporal relation to amiodarone, nitrofurantoin, methotrexate, immune checkpoint inhibitors
Tracheobronchitis without pneumonia — Purulent secretions without new infiltrate; signs and inflammatory markers less pronounced

Diagnostic workup

Diagnostic criteria

Clinical: new or progressive radiographic infiltrate + ≥2 of (fever >38°C, leukocytosis/leukopenia, purulent secretions, hypoxemia, increasing ventilator support). Microbiologic confirmation strongly preferred to guide therapy.

Labs

CBC, BMP, lactate, blood cultures × 2
Lower respiratory tract sampling BEFORE antibiotic change: endotracheal aspirate, bronchoalveolar lavage (BAL), or mini-BAL with quantitative culture (≥10⁴ CFU/mL BAL, ≥10⁶ tracheal aspirate)
Multiplex PCR panels for rapid pathogen identification
Procalcitonin trend can guide de-escalation/duration

Imaging

CXR — new or progressive infiltrate (essential for diagnosis)
CT chest if complicated (cavitation, empyema, abscess) or radiograph indeterminate

Diagnostic algorithm

Risk Tier	Empiric Coverage
HAP, no risk factors for MDR or mortality	Single agent active against MSSA + Pseudomonas (e.g., piperacillin-tazobactam, cefepime, levofloxacin)
HAP with MRSA risk OR high mortality risk	Antipseudomonal beta-lactam + MRSA coverage (vancomycin or linezolid)
VAP — all patients	Antipseudomonal beta-lactam + MRSA coverage; add second antipseudomonal if high resistance risk or septic shock
Known prior MDR pathogen	Tailor to prior isolate and antibiogram

ATS/IDSA 2016 empiric antibiotic stratification for HAP and VAP.

Treatment

First-line

Empiric therapy targets MRSA and Pseudomonas in most VAP and in HAP with risk factors
Antipseudomonal beta-lactam: piperacillin-tazobactam 4.5 g IV q6h (extended infusion), cefepime 2 g IV q8h, ceftazidime 2 g IV q8h, meropenem 1 g IV q8h, imipenem
MRSA coverage: vancomycin (trough 15-20 mg/L) OR linezolid 600 mg IV q12h
Add second antipseudomonal (aminoglycoside — amikacin/gentamicin/tobramycin — or fluoroquinolone — ciprofloxacin/levofloxacin) ONLY if high risk of resistance, septic shock, or local resistance >10-20% to monotherapy
Tailor based on local antibiogram and prior cultures within 90 days

Second-line / adjunct

De-escalate to narrowest agent once culture and sensitivities return; stop MRSA coverage if MRSA not isolated
Duration: 7 days for most HAP/VAP (ATS/IDSA 2016) — even with non-fermenting GNRs like Pseudomonas, provided clinical response
Difficult organisms: Acinetobacter — ampicillin-sulbactam (high dose), polymyxins, cefiderocol; ESBL — carbapenem; CRE — ceftazidime-avibactam, meropenem-vaborbactam, cefiderocol; Stenotrophomonas — TMP-SMX or levofloxacin
Source control: drain empyema, remove infected devices
Adjuncts to prevent VAP: head of bed 30-45°, daily sedation interruptions and spontaneous breathing trials, oral chlorhexidine (controversial), subglottic suction ETTs, early mobilization, stress ulcer prophylaxis only when indicated

Complications

Septic shock, multiorgan dysfunction
ARDS, prolonged mechanical ventilation, tracheostomy
Empyema, lung abscess, necrotizing pneumonia (especially S. aureus, Klebsiella)
Antibiotic-associated complications: C. difficile, AKI, antimicrobial resistance
Death — attributable mortality ~13% for VAP

PANCE pearls

HCAP (healthcare-associated pneumonia) was eliminated from ATS/IDSA guidelines in 2016 — it overestimated resistance and led to overtreatment.
Quantitative BAL has lower false-positive rate than endotracheal aspirate and can support de-escalation.
7-day course is appropriate for most HAP/VAP including Pseudomonas (PneumA trial), provided clinical response.
Procalcitonin algorithms can shorten antibiotic duration without worsening outcomes (SAPS trial).
Stenotrophomonas maltophilia — resistant to most beta-lactams and carbapenems; first-line is TMP-SMX.

References

ATS/IDSA 2016 — Management of Adults with Hospital-acquired and Ventilator-associated Pneumonia (Kalil et al., Clin Infect Dis 2016)
PneumA Trial — Comparison of 8 vs 15 Days of Antibiotic Therapy for VAP (Chastre et al., JAMA 2003)
SAPS Trial — Efficacy and Safety of Procalcitonin Guidance in Reducing Duration of Antibiotic Treatment in Critically Ill Patients (de Jong et al., Lancet Infect Dis 2016)
SHEA/IDSA 2022 — Strategies to Prevent Ventilator-Associated Pneumonia, Ventilator-Associated Events, and Nonventilator Hospital-Acquired Pneumonia (Klompas et al., Infect Control Hosp Epidemiol 2022)

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