Recommended Antibiotic Regimens for Community-Acquired Pneumonia
The first-line treatment for community-acquired pneumonia (CAP) should be 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
Outpatient Treatment
Patients without comorbidities:
- First choice: Macrolide (azithromycin 500mg on day 1, then 250mg daily for 4 days) 1, 2
- Alternative options:
- Doxycycline
- Respiratory fluoroquinolone (levofloxacin 750mg daily) 3
Patients with comorbidities:
- First choice: Beta-lactam (high-dose amoxicillin) plus macrolide 1
- Alternative option: Respiratory fluoroquinolone monotherapy 1, 3
Inpatient Treatment (Non-ICU)
- First choice: Intravenous ceftriaxone (1-2g daily) plus a macrolide (azithromycin 500mg daily) 1, 4
- Alternative options:
Inpatient Treatment (ICU)
- First choice: Ceftriaxone, cefotaxime, ampicillin-sulbactam, or piperacillin-tazobactam in combination with either a fluoroquinolone or macrolide 6, 1
- For suspected Pseudomonas: Consider piperacillin-tazobactam, cefoperazone/sulbactam, ceftazidime, cefepime, carbapenems, or fluoroquinolones; consider combination therapy for unstable patients 1
Treatment Duration
- Standard course: 5-7 days for most patients 1, 7
- Minimum: 5 days, with continuation until the patient is afebrile for 48-72 hours and has no more than one sign of clinical instability 1
- Extended course (14-21 days): For legionella, staphylococcal, or gram-negative enteric bacilli pneumonia 1
- Recent evidence suggests 3-day treatments may be effective even for hospitalized patients with CAP 7
Pathogen-Specific Treatment
| Pathogen | Treatment Options |
|---|---|
| Streptococcus pneumoniae | Beta-lactams (amoxicillin, cefotaxime, ceftriaxone) [6] |
| Mycoplasma pneumoniae | Macrolide (azithromycin preferred) [1] |
| Legionella spp. | Levofloxacin (preferred), moxifloxacin, or macrolide ± rifampicin [1] |
| Chlamydophila pneumoniae | Doxycycline, macrolide, levofloxacin, or moxifloxacin [1] |
| Pseudomonas aeruginosa | Antipseudomonal beta-lactam plus either fluoroquinolone or aminoglycoside [1] |
Switching from IV to Oral Therapy
Switch from IV to oral therapy when the patient:
- Is hemodynamically stable
- Is improving clinically
- Can ingest medications
- Has no evidence of gastrointestinal malabsorption
Most patients show clinical response within 3-5 days 6
Special Considerations
- In regions with high-level macrolide resistance (>25%), consider alternative regimens 1
- For patients with COPD and CAP, use a beta-lactam plus macrolide combination with consideration for pseudomonal coverage in at-risk patients 1
- For elderly patients or those with multiple comorbidities, consider broader coverage initially
- All patients with CAP should be tested for COVID-19 and influenza during appropriate seasons 4
Common Pitfalls and Caveats
- Failure to recognize resistant pathogens: Be aware of local resistance patterns, especially for S. pneumoniae
- Inadequate coverage for atypical pathogens: Ensure coverage for both typical and atypical pathogens
- Excessive treatment duration: Most uncomplicated CAP can be treated for 5-7 days
- Delayed switch from IV to oral therapy: Early conversion facilitates discharge and reduces costs without compromising outcomes 8
- Failure to recognize treatment failure: Consider incorrect diagnosis, inappropriate antibiotic, unusual pathogen, or complications if no response within 3-5 days 6
- Overuse of broad-spectrum antibiotics: Consider narrowing therapy once pathogens are identified to reduce resistance development
The most recent evidence supports shorter treatment durations (5-7 days or even 3 days in selected cases) for most patients with CAP, which can help reduce antibiotic resistance while maintaining efficacy 7.