What antibiotics are used to treat community-acquired pneumonia (CAP) in a hospital setting?

Antibiotic Treatment for Community-Acquired Pneumonia in the Hospital Setting

For hospitalized patients with community-acquired pneumonia (CAP), the recommended first-line therapy is a combination of an IV β-lactam (ceftriaxone, cefotaxime, or ampicillin-sulbactam) plus IV azithromycin. 1

Initial Antibiotic Selection Algorithm

Standard Medical Ward Patients:

1. First-line therapy options:

   • IV ceftriaxone 1-2 g IV daily PLUS azithromycin 500 mg IV daily 1
   • IV cefotaxime 1-2 g IV q8h PLUS azithromycin 500 mg IV daily 1
   • IV ampicillin-sulbactam 3 g IV q6h PLUS azithromycin 500 mg IV daily 1

2. Alternative therapy (for patients with β-lactam allergies or contraindications):

   • Respiratory fluoroquinolone monotherapy: levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily 1

Intensive Care Unit Patients:

1. First-line therapy:

   • IV β-lactam (ceftriaxone, cefotaxime) PLUS IV macrolide (erythromycin 1 g IV q6h) 2
   • For suspected aspiration or cavitary pneumonia: IV amoxicillin-clavulanate 2 g IV q6h 2

2. If MRSA risk factors present:

   • Add vancomycin 15 mg/kg IV q8-12h (target trough 15-20 mg/mL) OR linezolid 600 mg IV q12h 2

3. If Pseudomonas risk factors present:

   • Use antipseudomonal β-lactam (piperacillin-tazobactam 4.5 g IV q6h) PLUS an aminoglycoside AND consider adding a macrolide 2, 3

Risk Factors Requiring Special Consideration

MRSA Coverage Indicated When:

• Prior MRSA infection or colonization
• Recent IV antibiotic use within 90 days
• Hospitalization in a unit where MRSA prevalence among S. aureus isolates is >20% 2

Pseudomonas Coverage Indicated When:

• Structural lung disease (bronchiectasis, COPD)
• Recent antibiotic use
• Prior isolation of Pseudomonas 1

Treatment Duration

• Standard duration: 5 days if clinically stable (afebrile for 48-72 hours with stable vital signs) 1
• Extended duration (7-14 days) for:
  • Severe illness
  • Slow clinical response
  • Unusual pathogens (Pseudomonas, MRSA)
  • Complications (empyema, lung abscess) 1

Monitoring Response

• Assess clinical response within 48-72 hours of initiating therapy 1
• Key indicators of improvement:
  • Decreased fever
  • Improved respiratory symptoms
  • Stabilization of vital signs
  • Improved oxygenation

Common Pitfalls to Avoid

1. Macrolide monotherapy is inadequate due to increasing pneumococcal resistance rates, especially in patients >60 years or with comorbidities 1

2. Delayed antibiotic administration increases mortality - administer within 4-6 hours of presentation

3. Failure to de-escalate therapy once culture results are available, which contributes to antibiotic resistance

4. Overlooking atypical pathogens (Legionella, Mycoplasma) - recent evidence shows only 37% of patients with these pathogens received appropriate coverage 4

5. Inadequate duration of therapy - too short risks relapse, too long increases resistance and adverse effects

Special Considerations

• Renal impairment: Adjust dosing of β-lactams, fluoroquinolones, and vancomycin based on creatinine clearance 3

• Elderly patients: Higher risk of drug interactions and adverse effects; monitor closely

• COPD patients: Consider Pseudomonas coverage if severe COPD or recent antibiotic use 1

The evidence clearly demonstrates that combination therapy with a β-lactam plus a macrolide improves outcomes in hospitalized CAP patients by providing coverage for both typical and atypical pathogens, which reduces mortality and treatment failure rates compared to monotherapy regimens 1, 5.