What is the recommended treatment for community-acquired pneumonia (CAP) in adults?

Treatment of Community-Acquired Pneumonia in Adults

The first-line treatment for community-acquired pneumonia (CAP) in adults is an oral beta-lactam (high-dose amoxicillin or amoxicillin-clavulanate) plus an oral macrolide (azithromycin or clarithromycin), or alternatively, monotherapy with a respiratory fluoroquinolone (levofloxacin or moxifloxacin). 1

Treatment Algorithm Based on Setting

Outpatient Treatment

1. First-line options:

   • Beta-lactam (high-dose amoxicillin 1g TID or amoxicillin-clavulanate) plus macrolide (azithromycin 500mg on day 1, then 250mg daily for days 2-5) 1, 2
   • Doxycycline 100mg twice daily 1
   • Respiratory fluoroquinolone (levofloxacin 750mg daily or moxifloxacin 400mg daily) 1

2. For penicillin-allergic patients:

   • Respiratory fluoroquinolone (moxifloxacin, levofloxacin 750mg daily) 1

3. If patient received antibiotics in past 3 months:

   • Select an agent from a different class than previously used 1

Inpatient Treatment (non-ICU)

1. Preferred regimen:

   • IV beta-lactam plus IV/oral macrolide
   • IV respiratory fluoroquinolone monotherapy 1

2. For IV azithromycin:

   • 500mg IV daily for at least 2 days, then transition to oral 500mg daily to complete 7-10 days 3

Special Considerations

Patients at Risk for Resistant Pathogens

1. Pseudomonas risk factors:

   • Use antipseudomonal beta-lactam plus either ciprofloxacin/levofloxacin or aminoglycoside plus azithromycin/fluoroquinolone 1

2. MRSA risk factors:

   • Add vancomycin or linezolid to standard regimen 1

3. HIV-infected patients:

   • Avoid macrolide monotherapy due to increased risk of drug-resistant S. pneumoniae
   • Use fluoroquinolones cautiously when TB is suspected 1

Treatment Duration and Monitoring

1. Minimum treatment duration: 5 days 1

2. Criteria for discontinuation:

   • Patient afebrile for 48-72 hours
   • No more than one sign of clinical instability 1

3. Transition from IV to oral therapy when:

   • Hemodynamically stable
   • Clinically improving
   • Able to take oral medications
   • Normally functioning gastrointestinal tract 1

4. Monitoring response:

   • Evaluate at 48-72 hours (temperature, WBC, chest X-ray, oxygenation, sputum production) 1

Important Caveats and Pitfalls

1. Antibiotic resistance concerns:

   • Macrolide resistance is increasing in many regions, potentially limiting effectiveness as monotherapy 1
   • Fluoroquinolones carry risks of tendon rupture, peripheral neuropathy, and C. difficile infection 1

2. Diagnostic considerations:

   • Obtain cultures before initiating antibiotics, but do not delay the first dose 1
   • Assess disease severity and oxygenation status in all patients 1

3. Dosing adjustments:

   • No dosage adjustment needed for mild-moderate renal impairment
   • Use caution with severe renal impairment (GFR <10 mL/min) 3, 2
   • No specific dose adjustments recommended for hepatic impairment, but use caution 3, 2

4. Discharge considerations:

   • Ensure clinical stability, appropriate oral antibiotics to complete the course, and clear follow-up plan 1

By following these evidence-based recommendations, clinicians can optimize outcomes for adult patients with community-acquired pneumonia while minimizing complications and antibiotic resistance.