What are the recommended antibiotics for treating pneumonia?

Recommended Antibiotics for Pneumonia Treatment

For community-acquired pneumonia (CAP), amoxicillin is the first-line antibiotic treatment for most outpatients without comorbidities, while combination therapy or respiratory fluoroquinolones are recommended for those with comorbidities or requiring hospitalization. 1, 2

Outpatient Treatment Recommendations

Healthy Adults Without Comorbidities

• Amoxicillin 1 g three times daily (strong recommendation, moderate quality evidence) 1
• Doxycycline 100 mg twice daily (conditional recommendation, low quality evidence) 1, 2
• Macrolides (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) 1

Adults With Comorbidities

Comorbidities include chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia 1

Option 1: Combination Therapy

• β-lactam (one of the following):
  • Amoxicillin/clavulanate 500/125 mg three times daily, or 875/125 mg twice daily, or 2,000/125 mg twice daily 1
  • Cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily) 1

PLUS one of:

• Macrolide (azithromycin 500 mg on first day then 250 mg daily, or clarithromycin 500 mg twice daily) 1
• Doxycycline 100 mg twice daily 1

Option 2: Monotherapy

• Respiratory fluoroquinolone:
  • Levofloxacin 750 mg daily 1
  • Moxifloxacin 400 mg daily 1
  • Gemifloxacin 320 mg daily 1

Hospitalized Patient Treatment

Non-ICU Hospitalized Patients

• Combination therapy with β-lactam (ampicillin-sulbactam 1.5-3 g IV q6h, cefotaxime 1-2 g IV q8h, ceftriaxone 1-2 g IV daily, or ceftaroline 600 mg IV q12h) plus a macrolide (azithromycin 500 mg daily) 1
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1

ICU Patients

• β-lactam (as above) plus either a macrolide or a respiratory fluoroquinolone 1
• For patients with risk factors for Pseudomonas aeruginosa: antipseudomonal β-lactam plus either ciprofloxacin or macrolide plus aminoglycoside 1

Pathogen-Specific Considerations

Atypical Pathogens

• For Mycoplasma pneumoniae: macrolides (preferred), doxycycline, or respiratory fluoroquinolones 1, 3
• For Chlamydophila pneumoniae: azithromycin (preferred), other macrolides, tetracyclines, or fluoroquinolones 1, 3
• For Legionella species: newer macrolides (especially azithromycin) or respiratory fluoroquinolones (especially levofloxacin) 1

Common Bacterial Pathogens

• For Streptococcus pneumoniae: amoxicillin (for susceptible strains), respiratory fluoroquinolones 1, 4
• For Haemophilus influenzae: amoxicillin-clavulanate, cephalosporins, or fluoroquinolones (note increasing levofloxacin resistance in Taiwan) 1
• For Moraxella catarrhalis: amoxicillin-clavulanate, cephalosporins, or fluoroquinolones 1

Duration of Therapy

• 5-7 days for most uncomplicated pneumonia 1
• 7-10 days for moderate-to-severe pneumonia 1
• 14-21 days for Legionella pneumonia, staphylococcal pneumonia, or gram-negative enteric bacilli pneumonia 1, 2

Important Considerations and Caveats

• Azithromycin has FDA warnings for hepatotoxicity, QT prolongation, and risk of Clostridium difficile-associated diarrhea 5
• Fluoroquinolones should be used with caution due to risk of adverse events, including tendinopathy 1
• Patients with recent antibiotic exposure should receive an antibiotic from a different class due to increased risk of resistance 1
• Despite in vitro macrolide resistance in some pneumococcal strains, clinical efficacy may still be achieved with azithromycin therapy (in vivo-in vitro paradox) 4
• Short-course azithromycin therapy (3-5 days) has shown similar efficacy to longer courses of other antibiotics 6, 7
• Penicillin remains the drug of choice for Streptococcus pyogenes infections 5