What are the recommended antibiotics for treating pneumonia?

Recommended Antibiotics for Pneumonia

For pneumonia treatment, the recommended first-line antibiotics depend on the severity and setting, with hospitalized patients requiring combined therapy of amoxicillin plus a macrolide (erythromycin or clarithromycin), while severe cases need intravenous combination therapy with a broad-spectrum β-lactamase stable antibiotic plus a macrolide. 1, 2

Treatment Based on Setting and Severity

Outpatient Treatment (Non-Severe CAP)

• First-line: Amoxicillin monotherapy 1, 2
• Alternative: Macrolide (erythromycin or clarithromycin) for patients with penicillin intolerance 2

Hospitalized Patients (Non-Severe CAP)

• First-line: Combined oral therapy with amoxicillin and a macrolide (erythromycin or clarithromycin) 1, 2
• When oral treatment contraindicated: IV ampicillin or benzylpenicillin, together with erythromycin or clarithromycin 1
• Alternative for penicillin/macrolide intolerance: Fluoroquinolone with enhanced pneumococcal activity (levofloxacin is currently the only such agent licensed in the UK) 1, 3

Severe CAP

• First-line: IV combination of a broad-spectrum β-lactamase stable antibiotic (co-amoxiclav, cefuroxime, or ceftriaxone) plus a macrolide (clarithromycin or erythromycin) 1, 2
• Alternative: Fluoroquinolone with enhanced pneumococcal activity plus IV benzylpenicillin for those intolerant to β-lactams or macrolides 1

Special Considerations for Aspiration Pneumonia

• First-line: Amoxicillin/clavulanate (875 mg/125 mg twice daily or 500 mg/125 mg three times daily) 2, 4
• Alternative: Respiratory fluoroquinolone such as moxifloxacin 400 mg daily or levofloxacin 750 mg daily 2
• For severe cases in high-risk patients: Piperacillin-tazobactam 4.5g IV q6h 2, 5

Duration of Treatment

• Standard course: 7-10 days for non-severe pneumonia 1, 2
• Extended course: 14-21 days for legionella, staphylococcal, or Gram-negative enteric bacilli pneumonia 1
• High-dose, short-course options:
  • Levofloxacin 750mg once daily for 5 days (equivalent to 500mg once daily for 10 days) 3
  • Azithromycin short-course regimens have shown efficacy 6

Treatment Failure Management

• For patients failing to improve on initial therapy:
  1. Review clinical history, examination, and investigation results 1
  2. Consider additional investigations (repeat chest radiograph, CRP, WBC, microbiological testing) 1
  3. For non-severe pneumonia on amoxicillin monotherapy: Add or substitute a macrolide 1
  4. For non-severe pneumonia on combination therapy: Consider changing to a fluoroquinolone with effective pneumococcal coverage 1

Important Warnings and Precautions

• QT prolongation risk: Azithromycin and fluoroquinolones can cause QT prolongation and potentially fatal cardiac arrhythmias 7
• Hepatotoxicity: Azithromycin has been associated with abnormal liver function, hepatitis, and hepatic failure 7
• C. difficile risk: All antibiotics can cause C. difficile-associated diarrhea, ranging from mild to fatal colitis 7
• Fluoroquinolone use: Not recommended as first-line agents or for community use, but may be useful alternatives in selected hospitalized patients 1
• Antibiotic resistance concerns: Consider using narrow-spectrum agents where appropriate to reduce "collateral damage" and selection of resistant pathogens 8

Follow-up

• Clinical review should be arranged for all patients at around 6 weeks 1
• A chest radiograph should be arranged for patients with persistent symptoms or those at higher risk of underlying malignancy (especially smokers and those over 50 years) 1

By following these evidence-based recommendations, clinicians can optimize antibiotic therapy for pneumonia while minimizing risks of treatment failure and antibiotic resistance.