Treatment for Community-Acquired Pneumonia
The recommended first-line treatment for community-acquired pneumonia (CAP) is a combination of a beta-lactam (such as amoxicillin, ceftriaxone, or ampicillin) plus a macrolide (such as azithromycin or clarithromycin), with specific regimens determined by severity and treatment setting. 1, 2
Treatment Based on Patient Setting and Severity
Outpatient Treatment (Non-Severe CAP)
Previously healthy patients with no risk factors:
Patients with comorbidities or risk factors for drug-resistant Streptococcus pneumoniae:
Inpatient Treatment (Non-ICU)
Preferred regimen:
For penicillin-allergic patients:
ICU Treatment (Severe CAP)
Standard therapy:
- Beta-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a respiratory fluoroquinolone 2
If Pseudomonas suspected:
- Antipseudomonal beta-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin/levofloxacin OR an aminoglycoside plus azithromycin OR an aminoglycoside plus an antipneumococcal fluoroquinolone 2
If MRSA suspected:
- Add vancomycin or linezolid to standard regimen 2
Specific Antibiotic Dosing
Oral Therapy
- Azithromycin: 500mg on day 1, followed by 250mg daily on days 2-5 3
- Alternative azithromycin regimen: 500mg daily for 3 days 3, 4
- Amoxicillin: 1g three times daily 1
- Doxycycline: 100mg twice daily 5
Intravenous Therapy
- Azithromycin IV: 500mg daily for at least 2 days, then transition to oral therapy to complete 7-10 days 6
- Ceftriaxone: 1-2g daily 1
- Piperacillin-tazobactam: 3.375g every 6 hours (for patients with risk factors for resistant pathogens) 7
Duration of Therapy
- Minimum duration: 5 days 1
- Extended therapy: Continue until patient is afebrile for 48-72 hours and has no more than one sign of clinical instability 1
- Standard course: Generally 7-10 days for most patients 2, 1
- Severe pneumonia or specific pathogens: 14-21 days for legionella, staphylococcal, or gram-negative enteric bacilli pneumonia 2
Switching from IV to Oral Therapy
Transition from IV to oral antibiotics when:
- Patient shows clinical improvement 1, 6
- Patient is hemodynamically stable 1
- Patient can tolerate oral medications 2
- Typically after 1-2 days of IV therapy 1, 6
Management of Treatment Failure
If a patient fails to improve as expected:
- Review clinical history, examination, and all available test results 2
- Consider additional investigations (repeat chest radiograph, CRP, WBC) 2, 1
- For non-severe CAP with amoxicillin monotherapy: add or substitute a macrolide 2
- For non-severe CAP with combination therapy: consider switching to a fluoroquinolone 2
- For severe CAP not responding to combination therapy: consider adding rifampicin 2
Special Considerations
- Macrolide resistance: In regions with high-level macrolide resistance (>25%), consider alternative regimens 2
- Recent antibiotic use: Select an agent from a different class than what the patient received in the previous 3 months 2
- Influenza co-infection: Add oseltamivir if influenza is suspected or confirmed 2
- Smoking: Recommend smoking cessation and pneumococcal vaccination 1
Monitoring and Follow-up
- Monitor temperature, respiratory rate, pulse, blood pressure, mental status, and oxygen saturation at least twice daily 1
- Consider measuring CRP levels to assess treatment response 1
- Arrange clinical review for all patients at around 6 weeks 1
- Repeat chest radiograph for patients with persistent symptoms or physical signs, especially smokers and those over 50 years 1
The combination of a beta-lactam plus a macrolide has become the standard of care for CAP treatment due to the improved outcomes associated with macrolide coverage of atypical pathogens and potential anti-inflammatory effects 8, 9.