What are the recommended antibiotics for community-acquired pneumonia (CAP)?

Recommended Antibiotics for Community-Acquired Pneumonia (CAP)

For community-acquired pneumonia, treatment should be stratified based on patient setting, comorbidities, and severity of illness, with specific antibiotic regimens tailored to each scenario. 1

Outpatient Treatment

Healthy Adults Without Comorbidities

• 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 macrolide resistance <25% (conditional recommendation) 1

Outpatients With Comorbidities

Comorbidities include: chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia

Option 1: Combination Therapy

• Amoxicillin/clavulanate (500/125 mg three times daily, 875/125 mg twice daily, or 2000/125 mg twice daily) OR cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily)
• PLUS a macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily) 1

Option 2: Monotherapy

• Respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily) 1

Hospitalized Patients (Non-ICU)

• β-lactam (ceftriaxone, cefotaxime, ampicillin-sulbactam) PLUS a macrolide (preferred regimen) 1
• Alternative: Respiratory fluoroquinolone monotherapy 1

Hospitalized Patients (ICU)

• β-lactam (ceftriaxone, cefotaxime, ampicillin-sulbactam, or piperacillin-tazobactam) PLUS either a macrolide or a respiratory fluoroquinolone 1
• For patients with risk factors for Pseudomonas: antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS either a macrolide or a respiratory fluoroquinolone 1, 2

Duration of Therapy

• Minimum of 5 days for most patients 3
• Patients should be afebrile for 48-72 hours and have no more than one CAP-associated sign of clinical instability before discontinuing therapy 3
• For severe pneumonia, especially with suspected or confirmed Legionella or other atypical pathogens, consider extending treatment to 7-14 days 1

Important Clinical Considerations

Antimicrobial Resistance

• Streptococcus pneumoniae remains the most common identifiable cause of CAP and the most frequent cause of lethal CAP 1, 4
• Multidrug resistance in S. pneumoniae is increasing but standard regimens at appropriate doses remain effective in most cases 5
• In areas with high rates of resistant pathogens, monotherapy may be inadequate, necessitating combination therapy 3

Treatment Failure

• If no improvement after 48-72 hours, reassess diagnosis and consider alternative antimicrobial therapy 3
• Failure to respond may indicate incorrect diagnosis, inappropriate antibiotic choice/dose, unusual pathogen, adverse drug reaction, or complications like empyema 1

Special Populations

• Patients with recent antibiotic exposure should receive treatment with antibiotics from a different class due to increased risk of bacterial resistance 3
• For patients with COVID-19 or influenza during seasonal outbreaks, specific testing and appropriate antiviral therapy should be considered 4

Monitoring Response

• Most patients show clinical response within 3-5 days 1
• Radiographic improvement typically lags behind clinical response, and repeat chest imaging is generally not indicated for patients who respond clinically 1

The 2019 ATS/IDSA guidelines represent the most current comprehensive recommendations for CAP treatment and should be the primary reference for clinical decision-making, with adjustments based on local resistance patterns and patient-specific factors 1.