318.1 🎓 醫孞生版

318.1.0.1 📌 䞀頁重點

318.1.0.1.1 Definitions (IDSA/ATS 2016, 2019)
318.1.0.1.1.1 HAP (Hospital-Acquired Pneumonia)
  • Pneumonia developed ≥ 48 hours after admission
  • Not present at time of admission
  • Not ventilator-associated
318.1.0.1.1.2 VAP (Ventilator-Associated Pneumonia)
  • Pneumonia developed ≥ 48 hours after intubation + mechanical ventilation
  • Subset of HAP
318.1.0.1.1.3 HCAP (Healthcare-Associated Pneumonia) — RETIRED
  • 2016 IDSA/ATS removed this category
  • Was: pneumonia in patients with healthcare contacts (dialysis, nursing home, recent hospitalization, IV therapy, wound care)
  • Now: assessed by individual MDR risk factors
318.1.0.1.1.4 MDR (Multidrug-Resistant) Pathogens
  • Resistant to 3+ classes of antibiotics
  • High prevalence in HAP/VAP
  • Drives empiric therapy choices
318.1.0.1.2 Epidemiology
318.1.0.1.2.1 Incidence
  • HAP: 0.5-1% of all hospitalized; ~ 10% of medical ICU patients
  • VAP: 5-40% (varies by setting); 1-3% per day of mechanical ventilation
  • Cause significant morbidity + mortality (15-50%)
  • Major contributor to ICU costs + length of stay
318.1.0.1.2.2 Risk Factors

Patient Factors: - Age, smoking, chronic disease (COPD, DM, CKD, HF) - Immunosuppression - Recent surgery - Decreased mental status (aspiration) - GI bleeding

Healthcare Factors: - Prolonged hospitalization - ICU admission - Mechanical ventilation - Reintubation - Inadequate hand hygiene - Contaminated equipment

Specific MDR Risk Factors (Drive Empiric Therapy): 1. IV antibiotics within 90 days 2. Septic shock at pneumonia onset 3. ARDS preceding pneumonia 4. ≥ 5 days hospitalization prior to pneumonia 5. Acute renal replacement therapy prior 6. Local prevalence of MDR pathogens > 25% 7. MRSA / Pseudomonas colonization

318.1.0.1.3 Common Pathogens
318.1.0.1.3.1 Bacterial (Most HAP/VAP)
  • Gram-negative:
    • Pseudomonas aeruginosa (most common in VAP)
    • Acinetobacter baumannii
    • Klebsiella pneumoniae (ESBL, carbapenemase-producing)
    • E. coli
    • Stenotrophomonas maltophilia
    • Burkholderia cepacia
    • Enterobacter species
  • Gram-positive:
    • Staphylococcus aureus (MSSA, MRSA)
    • Streptococcus pneumoniae (less common in HAP, more so early)
318.1.0.1.3.2 Less Common
  • Anaerobes (aspiration)
  • Legionella (institutional outbreaks)
  • Viral (influenza, RSV, COVID-19 in healthcare settings)
  • Fungal (immunocompromised, prolonged stay)
318.1.0.1.4 Clinical Features
318.1.0.1.4.1 Diagnosis Challenging
  • Many ICU patients have:
    • Fever, leukocytosis, infiltrates from non-infectious causes
    • Atelectasis, ARDS, pulmonary edema, drug-induced infiltrates
  • Distinguishing pneumonia from these is critical
318.1.0.1.4.2 Clinical Criteria
  • New / progressive radiographic infiltrate PLUS
  • ≥ 2 of:
    • Fever > 38°C
    • Leukocytosis or leukopenia
    • Purulent secretions
318.1.0.1.4.3 CPIS (Clinical Pulmonary Infection Score)
  • Temperature, leukocytes, secretions, oxygenation, radiograph, culture
  • Score > 6 suggests pneumonia
  • Limited specificity
318.1.0.1.4.4 Microbiological Diagnosis

Quantitative Cultures: - Tracheal aspirate (≥ 10^6 CFU/mL): less invasive - Bronchoalveolar lavage (BAL) (≥ 10^4 CFU/mL): more specific - Protected specimen brush (PSB) (≥ 10^3 CFU/mL): most specific

Non-Invasive Approach Reasonable: - Tracheal aspirate quantitative or semiquantitative - Adequate for most cases

318.1.0.1.5 Treatment
318.1.0.1.5.1 Empiric Therapy Selection

Step 1: Assess for Pseudomonas + MDR risk - If high risk → double Pseudomonas coverage + MRSA coverage - If low risk → single anti-Pseudomonas

Step 2: Assess for MRSA risk - IV antibiotics within 90 days, MRSA colonization, prevalence > 10-20% in unit - Add vancomycin or linezolid

318.1.0.1.5.2 Empiric Regimen Examples

Pseudomonas Cover (Choose 1): - Piperacillin-tazobactam 4.5 g IV q6h - Cefepime 2 g IV q8h - Meropenem 1 g IV q8h - Ceftazidime-avibactam (for ESBL/CRE) - Ceftolozane-tazobactam (MDR Pseudomonas) - Imipenem-cilastatin - Aztreonam (penicillin allergy)

Second Anti-Pseudomonas (If High MDR Risk): - Tobramycin or gentamicin or amikacin (aminoglycoside) - Ciprofloxacin or levofloxacin

MRSA Cover: - Vancomycin (trough 15-20 ÎŒg/mL) - Linezolid 600 mg IV BID

Anaerobic Cover (if aspiration suspected): - β-lactam-β-lactamase inhibitor (already cover anaerobes) - Add metronidazole if not

318.1.0.1.5.3 De-Escalation
  • Within 48-72 hours of culture results
  • Narrow to specific agent
  • Reduces resistance pressure
318.1.0.1.5.4 Specific Pathogens

Pseudomonas: - Combination therapy for severe (β-lactam + aminoglycoside or fluoroquinolone) — debated benefit - Monotherapy if susceptible + responding - 7-day duration if non-MDR; 14 days if MDR or complicated

MRSA: - Vancomycin (trough 15-20) - Linezolid alternative (especially with renal disease) - Daptomycin NOT for pneumonia (inactivated by surfactant)

Acinetobacter: - Often MDR - Sulbactam, colistin, tigecycline, eravacycline, cefiderocol - Combination often

ESBL Enterobacteriaceae: - Carbapenem (meropenem, imipenem, ertapenem) - Ceftazidime-avibactam alternative - Avoid cephalosporins

Carbapenem-Resistant Enterobacteriaceae (CRE): - Ceftazidime-avibactam - Meropenem-vaborbactam - Imipenem-relebactam - Cefiderocol - Eravacycline - Colistin (last resort; nephrotoxic)

Stenotrophomonas: - TMP-SMX first-line - Levofloxacin alternative

318.1.0.1.5.5 Duration

Standard: 7 days for most HAP/VAP - PneumA Trial (2003): 8-day vs 15-day course — equivalent - Shorter duration reduces resistance + costs - Exception: MDR organisms, complicated (abscess, empyema, bacteremia), poor response

MDR Pseudomonas: 14 days Complicated: 14-21 days

318.1.0.1.5.6 Treatment Failure
  • Within 72 hours
  • Causes:
    • Inappropriate empiric (wrong organism, resistance)
    • Complication (empyema, abscess)
    • Wrong diagnosis (PE, ARDS, atelectasis, malignancy)
  • Re-evaluate clinically + imaging + cultures + bronchoscopy
318.1.0.1.6 VAP Prevention Bundle (Class I)
318.1.0.1.6.1 Bundle Components (2024 Updates)
  1. Head of bed 30-45° (semi-recumbent)
  2. Daily SAT (spontaneous awakening trial) + SBT (spontaneous breathing trial)
  3. Oral chlorhexidine (controversial 2024 — some recommend discontinuation due to potential pneumonia and mortality concerns)
  4. DVT prophylaxis
  5. PUD prophylaxis (with PPI or H2 blocker; balance with C. diff risk)
  6. Daily oral care + dental hygiene
  7. Subglottic suction endotracheal tubes
  8. Early ambulation
  9. Cuff pressure monitoring (20-30 cm H2O)
  10. Selective decontamination of digestive tract (SDD) — Europe more; not universal
  11. Hand hygiene + contact precautions
  12. Reduce duration of mechanical ventilation (above)
318.1.0.1.6.2 Outcomes
  • Bundle adherence reduces VAP
  • Multidisciplinary implementation
  • ICU + checklist culture critical
318.1.0.1.7 Specific Newer Antibiotics for MDR (2020s)
318.1.0.1.7.1 Ceftolozane-Tazobactam (Zerbaxa)
  • Anti-Pseudomonas (including MDR)
  • Approved for HAP/VAP (ASPECT-NP trial)
318.1.0.1.7.2 Ceftazidime-Avibactam (Avycaz)
  • ESBL, AmpC, KPC (carbapenemase)
  • Pseudomonas
  • Approved for HAP/VAP
318.1.0.1.7.3 Meropenem-Vaborbactam (Vabomere)
  • CRE (KPC)
  • Tango-1, Tango-2 trials
318.1.0.1.7.4 Imipenem-Relebactam (Recarbrio)
  • CRE, MDR Pseudomonas
  • RESTORE-IMI trials
318.1.0.1.7.5 Cefiderocol (Fetroja)
  • “Siderophore cephalosporin” — uses iron transport
  • MDR Pseudomonas, Acinetobacter, Stenotrophomonas, CRE
  • Caution: APEKS-NP trial showed mortality signal in critically ill
318.1.0.1.7.6 Eravacycline (Xerava)
  • Broad including MDR + Acinetobacter
318.1.0.1.7.7 Plazomicin
  • Aminoglycoside
  • ESBL, CRE
  • Less ototoxic + nephrotoxic
318.1.0.1.8 Special Considerations
318.1.0.1.8.1 VAP in COVID-19
  • Increased risk due to prolonged ventilation
  • High prevalence
  • Same empiric principles
  • Aspergillus + invasive fungal co-infection possible
  • ETI/dexamethasone considerations
318.1.0.1.8.2 VAP in Immunocompromised
  • Wider pathogen consideration (fungal, viral, parasitic)
  • Bronchoscopy + BAL often needed
  • Broader empiric
318.1.0.1.8.3 Anti-Aspergillus in Critically Ill
  • COVID-associated pulmonary aspergillosis (CAPA)
  • Influenza-associated pulmonary aspergillosis (IAPA)
  • Voriconazole or isavuconazole
  • Consider in non-responders, ICU patients
318.1.0.1.9 Procalcitonin in HAP/VAP
  • Stewardship tool
  • Trend down → consider stopping
  • < 0.5 ng/mL: bacterial unlikely
  • Multiple RCTs show shorter antibiotic duration without harm

318.1.0.2 🩺 床邊速查

  • HAP: ≥ 48 h after admission; VAP: ≥ 48 h after intubation
  • HCAP RETIRED (2016 IDSA/ATS)
  • MDR risk factors: recent IV abx 90d, septic shock, ARDS, prolonged hosp ≥ 5d, MRSA/Pseudo colonization
  • Empiric: anti-Pseudo β-lactam + MRSA cover (vanc/linezolid); double Pseudo if high MDR risk
  • Pseudomonas: pip-tazo, cefepime, meropenem; severe + AG/FQ
  • Acinetobacter: sulbactam, colistin, cefiderocol
  • CRE: ceftaz-avibactam, meropenem-vaborbactam, imipenem-relebactam, cefiderocol
  • Duration: 7 days for most (PneumA); 14 for MDR/complicated
  • VAP prevention bundle: HOB 30-45°, SAT/SBT daily, oral care, subglottic suction