Pneumonia Management

Overview

Classification

Key Pathogens

CAP

• Typical bacteria: S. pneumoniae (most common), H. influenzae, S. aureus, gram-negative bacilli (account for ~30% combined)
• Atypical: Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella (<5% each)
• Viral: Influenza, RSV, hMPV, SARS-CoV-2 (~20-30% of cases; higher during COVID)
• No pathogen confirmed: >50% of cases

HAP/VAP

• S. aureus (10-20%; 50% may be MRSA)
• Pseudomonas aeruginosa (10-20%)
• Enteric gram-negative bacilli (20-40%)
• Acinetobacter baumannii (5-10%)
• MDR rates are high: ~28-35% of Pseudomonas resistant to cefepime; 56-61% of Acinetobacter carbapenem-resistant

Step 1: Severity Assessment

Pneumonia Severity Index (PSI) - preferred

• Class I-III (≤90 points): outpatient management likely safe
• Class IV-V (>90 points): hospitalization indicated

• 130 points or CURB-65 >3: ICU/intermediate care

CURB-65 (simplified, for when labs unavailable)

• 0-1: outpatient
• 2: consider admission
• 3-5: hospital/ICU admission

Step 2: Empiric Antibiotic Treatment

CAP - Outpatient

CAP - Inpatient (Non-severe, no MRSA/Pseudomonas risk)

• Respiratory fluoroquinolone monotherapy
• OR β-lactam (ampicillin-sulbactam, ceftriaxone, cefotaxime) + macrolide or doxycycline

CAP - Severe (ICU admission)

• Dual therapy: β-lactam + macrolide or respiratory fluoroquinolone
• If MRSA risk (prior parenteral antibiotics in last 90 days, prior MRSA infection): add vancomycin or linezolid
  • A rapid negative nasal MRSA PCR has high negative predictive value and can guide withholding MRSA coverage
• If Pseudomonas risk: use antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, meropenem)
• Anaerobic coverage (clindamycin) only if lung abscess or empyema suspected - NOT routine

HAP / VAP

Step 3: Antibiotic Duration

• CAP (most patients): minimum 5 days - extend only if clinical stability not achieved
• Suspected MRSA or Pseudomonas CAP: 7 days
• Non-ICU CAP that is clinically stable: 3 days of IV β-lactam may be adequate before switching to oral
• HAP/VAP: typically 7 days; de-escalate based on cultures

Step 4: Adjunctive / Supportive Therapy

Corticosteroids

• NOT recommended routinely in CAP
• Exception: refractory septic shock (hydrocortisone 200 mg/day for 4-8 days) - supported by some guidelines
• The 2026 ATS CAP Guideline addressed systemic corticosteroids as one of its four key updated questions

Viral Co-infection

• Influenza confirmed: give oseltamivir regardless of symptom duration + empirical antibacterials (high prevalence of bacterial co-infection)
• SARS-CoV-2 confirmed: withhold antibacterials unless bacterial co-infection suspected; use antivirals ± monoclonal antibodies for high-risk patients

Procalcitonin

• Professional societies recommend against using procalcitonin to decide whether to start antibiotics in suspected CAP

Oxygen / Respiratory Support

• Target SpO₂ ≥94%; use supplemental O₂, high-flow nasal cannula, or NIV as needed
• Mechanical ventilation for respiratory failure

Lung Ultrasound (2026 ATS update)

• The 2026 ATS CAP Guideline specifically evaluated lung ultrasound as a diagnostic tool - now an evidence-based alternative to chest X-ray in appropriate settings

Step 5: Prevention

• Smoking cessation
• Good oral hygiene (reduces aspiration risk)
• VAP bundle: head-of-bed elevation 30-45°, oral chlorhexidine decontamination, minimize sedation, daily spontaneous breathing trials, avoid unnecessary reintubation

Complications to Monitor

Key Recent Guideline Updates (2026)

1. Lung ultrasound for CAP diagnosis
2. Empiric antibacterials when a respiratory virus test is positive (i.e., whether to still give antibiotics)
3. Antibiotic duration - shorter courses supported
4. Systemic corticosteroids in CAP