What are the recommended antibiotics for treating pneumonia?

Recommended Antibiotics for Pneumonia

For community-acquired pneumonia (CAP), the recommended first-line antibiotic treatment depends on the severity and setting, with amoxicillin, doxycycline, or a macrolide for outpatients without comorbidities, and combination therapy with a β-lactam plus macrolide for hospitalized patients. 1, 2

Outpatient Treatment

Healthy Adults Without Comorbidities

• First-line options:
  • Amoxicillin 1 g three times daily 1
  • Doxycycline 100 mg twice daily 1, 3
  • 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% 1

Adults With Comorbidities

(Chronic heart/lung/liver/renal disease, diabetes, alcoholism, malignancy, asplenia)

• Combination therapy:

  • Amoxicillin/clavulanate (500/125 mg three times daily or 875/125 mg twice daily) OR cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily)
  • PLUS a macrolide OR doxycycline 100 mg twice daily 1

• OR Monotherapy:

  • Respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily) 1, 4

Hospitalized Patients (Non-Severe CAP)

• Preferred regimen:

  • Combined therapy with a β-lactam (amoxicillin, co-amoxiclav, or cephalosporin) plus a macrolide (clarithromycin or erythromycin) 1

• Alternative for penicillin-allergic patients:

  • Respiratory fluoroquinolone (levofloxacin or moxifloxacin) 1, 2

Severe CAP (ICU Admission)

Without Risk Factors for Pseudomonas:

• Non-antipseudomonal cephalosporin (cefotaxime or ceftriaxone) PLUS macrolide
• OR moxifloxacin or levofloxacin (with or without cephalosporin) 1

With Risk Factors for Pseudomonas:

• Antipseudomonal cephalosporin OR acylureidopenicillin/β-lactamase inhibitor OR carbapenem
• PLUS ciprofloxacin OR macrolide plus aminoglycoside 1

Duration of Treatment

• Non-severe CAP: 5-7 days 2
• Severe CAP (microbiologically undefined): 10 days 1
• Specific pathogens:
  • Legionella, staphylococcal, or Gram-negative enteric bacilli: 14-21 days 1

Pathogen-Specific Treatment

Atypical Pathogens

• Mycoplasma pneumoniae: Macrolides, tetracyclines, or fluoroquinolones 1
• Chlamydophila pneumoniae: Azithromycin (preferred), other macrolides, fluoroquinolones, or tetracyclines 1
• Legionella species: Levofloxacin or azithromycin (with or without rifampicin for severe cases) 1

Clinical Considerations

Efficacy Comparisons

• A 3-day course of azithromycin 1g daily is as effective as a 7-day course of amoxicillin-clavulanate for mild-to-moderate CAP 5
• Doxycycline shows comparable efficacy to macrolides and fluoroquinolones for mild-to-moderate CAP 3

Common Pitfalls to Avoid

1. Inappropriate antibiotic selection: Failing to cover both typical and atypical pathogens in hospitalized patients
2. Inadequate duration: Stopping antibiotics before clinical stability is achieved
3. Delayed IV-to-oral switch: Continue IV antibiotics when patient is clinically stable and able to take oral medications
4. Overuse of broad-spectrum antibiotics: Leading to antibiotic resistance
5. Ignoring regional resistance patterns: Local epidemiology should guide empiric therapy

When to Switch to Oral Therapy

• When patient is clinically stable (afebrile for 24-48 hours and clinically improving) 2
• No more than one CAP-associated sign of clinical instability before stopping therapy 2

Treatment Failure

• For patients not improving on initial therapy:
  • If on amoxicillin monotherapy: Add or substitute a macrolide 1
  • If on combination therapy in hospital: Consider switching to a respiratory fluoroquinolone 1
  • Review diagnosis, consider further investigations, and evaluate for complications 1

Remember that antibiotic selection should be guided by local resistance patterns, and therapy should be adjusted based on microbiological results when available.