What is the first-line treatment for Community-Acquired Pneumonia (CAP) according to guidelines?

First-Line Treatment for Community-Acquired Pneumonia (CAP)

For outpatient treatment of CAP in healthy adults without comorbidities, the first-line therapy is amoxicillin 1 g three times daily. 1

Treatment Algorithm Based on Patient Setting and Risk Factors

Outpatient Treatment

1. Healthy adults without comorbidities:

• First choice: Amoxicillin 1 g three times daily (strong recommendation, moderate quality evidence) 1
• Alternative options:
  • Doxycycline 100 mg twice daily (conditional recommendation, low quality evidence) 1
  • Macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily) only in areas with pneumococcal resistance to macrolides <25% (conditional recommendation, moderate quality evidence) 1

2. Outpatients with comorbidities (chronic heart, lung, liver, renal disease; diabetes; alcoholism; malignancy; asplenia):

• Combination therapy:
  • Amoxicillin/clavulanate (500 mg/125 mg three times daily, or 875 mg/125 mg twice daily, or 2,000 mg/125 mg twice daily) OR cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily); AND
  • Macrolide (azithromycin 500 mg on first day then 250 mg daily, clarithromycin 500 mg twice daily) OR doxycycline 100 mg twice daily 1
• OR Monotherapy:
  • Respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily) 1

Inpatient Treatment (Non-ICU)

• First choice: β-lactam (ampicillin + sulbactam 1.5-3 g every 6h, cefotaxime 1-2 g every 8h, ceftriaxone 1-2 g daily, or ceftaroline 600 mg every 12h) plus a macrolide (azithromycin 500 mg daily or clarithromycin 500 mg twice daily) 1
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1
• For penicillin/macrolide allergic patients: β-lactam plus doxycycline 100 mg twice daily 1

Inpatient Treatment (ICU)

• First choice: β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a respiratory fluoroquinolone 1
• For Pseudomonas risk: Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin/levofloxacin OR an aminoglycoside plus azithromycin OR an aminoglycoside plus an antipneumococcal fluoroquinolone 1

Important Clinical Considerations

Duration of Therapy

• Minimum 5 days for most patients 1
• Should be afebrile for 48-72 hours before discontinuing therapy 1
• Longer duration (10-14 days) may be needed for severe pneumonia 1

Switching from IV to Oral Therapy

• Switch when patient is hemodynamically stable, clinically improving, able to take oral medications, and has normal GI function 1
• Oral therapy is appropriate for most hospitalized patients with non-severe CAP 1

Special Considerations

• If patient has received antibiotics within the previous 3 months, select an agent from a different class to avoid resistance 1
• In areas with high pneumococcal resistance to macrolides (>25%), avoid macrolide monotherapy 1
• Fluoroquinolones should be reserved for patients with risk factors or contraindications to first-line agents to minimize resistance development 1

Common Pitfalls to Avoid

1. Using macrolide monotherapy in areas with high resistance: Macrolide resistance among pneumococci is increasing, making monotherapy potentially ineffective in many regions 1

2. Delaying antibiotic administration: For hospitalized patients, first antibiotic dose should be administered while still in the emergency department 1

3. Failing to adjust therapy based on prior antibiotic exposure: Patients who have received antibiotics in the previous 3 months should receive a different class of antibiotics due to increased risk of resistance 1

4. Not considering local resistance patterns: Treatment should be guided by local antibiotic resistance patterns when available 1

5. Prolonged IV therapy when oral therapy is appropriate: Most non-severe hospitalized patients can be adequately treated with oral antibiotics 1

The 2019 ATS/IDSA guidelines provide the most current evidence-based recommendations for CAP treatment, emphasizing appropriate empiric therapy based on patient risk factors, setting of care, and local resistance patterns to optimize outcomes related to morbidity and mortality.