Treatment for Community-Acquired Pneumonia (CAP)
The recommended treatment for community-acquired pneumonia should be stratified based on patient setting and risk factors, with outpatients without comorbidities receiving amoxicillin 1g every 8 hours or doxycycline 100mg twice daily, while hospitalized non-ICU patients should receive a β-lactam plus a macrolide or a respiratory fluoroquinolone. 1, 2
Outpatient Treatment
Patients without comorbidities:
- Amoxicillin 1g every 8 hours (first-line therapy) 1, 2
- Doxycycline 100mg twice daily (alternative first-line therapy), with consideration for 200mg first dose to achieve adequate serum levels more rapidly 1, 2
- Macrolide (e.g., azithromycin 500mg on day 1, then 250mg daily for days 2-5) for patients without recent antibiotic use 2, 3
Patients with comorbidities or recent antibiotic use:
- Respiratory fluoroquinolone (e.g., levofloxacin 750mg daily or moxifloxacin 400mg daily) 1, 4
- β-lactam (amoxicillin-clavulanate, cefpodoxime, or high-dose amoxicillin) plus a macrolide 1, 2
- Patients with recent exposure to one antibiotic class should receive treatment from a different class due to increased risk of bacterial resistance 1, 2
Hospitalized Non-ICU Patients
- Combination therapy with a β-lactam (ampicillin-sulbactam 1.5-3g every 6h, cefotaxime 1-2g every 8h, ceftriaxone 1-2g daily, or ceftaroline 600mg every 12h) plus a macrolide (azithromycin 500mg daily or clarithromycin 500mg twice daily) 1, 2
- Respiratory fluoroquinolone monotherapy (levofloxacin 750mg daily or moxifloxacin 400mg daily) 1, 2
- For patients with contraindications to both macrolides and fluoroquinolones: β-lactam plus doxycycline 100mg twice daily 1
Severe CAP/ICU Treatment
- For patients without risk factors for Pseudomonas: β-lactam plus either a macrolide or a respiratory fluoroquinolone 2, 5
- For patients with risk factors for Pseudomonas: antipseudomonal β-lactam plus either ciprofloxacin/levofloxacin or an aminoglycoside plus azithromycin 2
- Add vancomycin or linezolid when community-acquired MRSA is suspected 2
Duration of Therapy
- Minimum duration of 5 days for most patients 2, 5
- Patient should be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuing therapy 2
- Recent evidence supports shorter durations (3 days) for non-severe or moderate CAP when clinical stability is achieved by day 3 6
- Treatment should generally not exceed 8 days in a responding patient 2
Special Considerations
Timing of Antibiotic Administration
- For hospitalized patients, the first antibiotic dose should be administered while still in the emergency department 2, 5
- Early administration is associated with improved outcomes 2
Antibiotic Selection Considerations
- Despite concerns about adverse events with fluoroquinolones, they remain justified for adults with comorbidities due to their performance in numerous studies, low resistance rates, coverage of both typical and atypical organisms, and convenience of monotherapy 1
- The FDA has issued warnings about increasing reports of adverse events related to fluoroquinolone use 1
- Fluoroquinolone therapy may lead to a higher rate of adverse events but lower rate of retreatment compared to macrolides in outpatient settings 7
Common Pitfalls and Caveats
- Overreliance on fluoroquinolones can lead to resistance; they should be reserved for patients with β-lactam allergies or when specifically indicated 2
- Inadequate coverage for atypical pathogens should be avoided, ensuring coverage for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila 2, 8
- Multidrug resistance in bacteria causing CAP is a growing concern, particularly for S. pneumoniae, K. pneumoniae, and P. aeruginosa 9
- Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy 2
- For patients who fail to improve as expected, consider a careful review of clinical history, examination, and additional investigations 5