What are the recommended antibiotic choices for treating pneumonia?

Recommended Antibiotic Choices for Pneumonia

For pneumonia treatment, the first-line antibiotic choice depends on the setting (community-acquired vs. hospital-acquired) and patient risk factors, with amoxicillin being preferred for uncomplicated community-acquired pneumonia and broader coverage needed for hospital-acquired pneumonia.

Community-Acquired Pneumonia (CAP)

Outpatient Treatment

• First-line therapy:

  • Mild to moderate CAP: Amoxicillin 1g three times daily (3g/day) for adults 1
  • Children: Amoxicillin 90 mg/kg/day in 2 doses or 45 mg/kg/day in 3 doses 1
  • Standard duration: 5-7 days for uncomplicated cases 1

• For patients with penicillin allergy:

  • Respiratory fluoroquinolones (levofloxacin 750 mg daily) 1, 2
  • Doxycycline (with limited activity against drug-resistant S. pneumoniae) 1
  • Macrolides (with caution due to increasing resistance) 1

Inpatient Treatment (Non-ICU)

• Preferred regimen: β-lactam (ampicillin, ceftriaxone) plus a macrolide 3, 4

  • Ceftriaxone 1g IV daily plus azithromycin 500 mg IV/PO daily 4
  • This combination showed 91.5% favorable clinical outcomes compared to 89.3% with levofloxacin 4

• Alternative: Respiratory fluoroquinolone monotherapy

  • Levofloxacin 750 mg IV/PO daily for 5 days (equivalent efficacy to 500 mg for 10 days) 5

Severe CAP/ICU Admission

• Preferred regimen: Two antipseudomonal agents if risk factors for Pseudomonas present 3

  • Options include:
    • Piperacillin-tazobactam 4.5g IV q6h
    • Cefepime 2g IV q8h
    • Meropenem 1g IV q8h
  • Plus either a respiratory fluoroquinolone or an aminoglycoside 3

• Add MRSA coverage if risk factors present:

  • Vancomycin 15 mg/kg IV q8-12h (target trough 15-20 mg/mL) or
  • Linezolid 600 mg IV q12h 3

Hospital-Acquired Pneumonia (HAP)

Not at High Risk of Mortality and No MRSA Risk Factors

• Monotherapy with:
  • Piperacillin-tazobactam 4.5g IV q6h
  • Cefepime 2g IV q8h
  • Levofloxacin 750 mg IV daily
  • Imipenem 500 mg IV q6h
  • Meropenem 1g IV q8h 3

High Risk of Mortality or Recent Antibiotic Use

• Combination therapy with two of the following (avoid using two β-lactams):
  • Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, meropenem)
  • Antipseudomonal fluoroquinolone (levofloxacin, ciprofloxacin)
  • Aminoglycoside (amikacin, gentamicin, tobramycin)
  • Plus MRSA coverage (vancomycin or linezolid) 3

Special Considerations

Pathogen-Specific Treatment

1. Streptococcus pneumoniae:

   • Penicillin-susceptible: β-lactam antibiotics (penicillin, amoxicillin, cephalosporins) 3
   • Penicillin-resistant: Levofloxacin, high-dose amoxicillin, or ceftriaxone 1, 6
   • For bacteremic pneumococcal pneumonia: Combination therapy recommended for at least 10-14 days 3

2. Staphylococcus aureus:

   • MSSA: Oxacillin, flucloxacillin, or 1st generation cephalosporin 3
   • MRSA: Vancomycin (target trough 15-20 mg/mL) or linezolid 3

3. Pseudomonas aeruginosa:

   • Combination therapy with antipseudomonal β-lactam plus either fluoroquinolone or aminoglycoside 3

Duration of Therapy

• Uncomplicated CAP: 5-7 days (discontinue after being afebrile for 48-72 hours with clinical stability) 1
• HAP: 7-14 days based on clinical response 1
• Bacteremic pneumococcal pneumonia: 10-14 days minimum 3

Antibiotic Resistance Concerns

• Avoid fluoroquinolones in patients with suspected tuberculosis to prevent delayed diagnosis and resistance 3
• Monitor for emergence of resistance, particularly with Pseudomonas aeruginosa 2
• Reassess therapy within 48-72 hours; if no improvement, consider alternative pathogens or resistance 1

Antibiotics to Avoid

• Trimethoprim-sulfamethoxazole (inadequate activity against S. pneumoniae) 1
• First-generation cephalosporins (inadequate activity) 1
• Macrolides as monotherapy in areas with high resistance rates 1

Remember to adjust therapy based on culture results when available, and consider local resistance patterns when selecting empiric therapy.