Drug of Choice for Community-Acquired Pneumonia
For community-acquired pneumonia (CAP), the drug of choice depends on patient setting, comorbidities, and risk factors, with a respiratory fluoroquinolone (levofloxacin, moxifloxacin) or a β-lactam plus macrolide combination being the preferred options for most hospitalized patients. 1, 2
Outpatient Treatment
Previously Healthy Adults (No Comorbidities)
- A macrolide (azithromycin, clarithromycin, or erythromycin) is recommended as first-line therapy for previously healthy patients with no risk factors for drug-resistant S. pneumoniae 1, 2
- Doxycycline is an acceptable alternative for patients without comorbidities 1, 2
- Macrolide monotherapy should only be used in areas where pneumococcal resistance to macrolides is <25% 2
Patients with Comorbidities
- A respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin 750 mg) is recommended for patients with comorbidities such as chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancies; asplenia; immunosuppression; or recent antibiotic use 1, 2
- Alternatively, a β-lactam plus a macrolide combination can be used, with high-dose amoxicillin (1g three times daily) or amoxicillin-clavulanate (2g twice daily) as the preferred β-lactam options 1, 3
- Alternative β-lactams include ceftriaxone, cefpodoxime, and cefuroxime 1
Inpatient Treatment (Non-ICU)
- A respiratory fluoroquinolone (levofloxacin, moxifloxacin) as monotherapy is strongly recommended 1
- Alternatively, a β-lactam plus a macrolide combination is equally effective 1
- Preferred β-lactam agents include cefotaxime, ceftriaxone, and ampicillin; ertapenem can be used for selected patients with risk factors for gram-negative infections 1
- For penicillin-allergic patients, a respiratory fluoroquinolone should be used 1
Inpatient Treatment (ICU)
- A β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a respiratory fluoroquinolone is strongly recommended 1
- For penicillin-allergic patients, a respiratory fluoroquinolone plus aztreonam is recommended 1
- For suspected Pseudomonas infection, an antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin/levofloxacin or an aminoglycoside and azithromycin is recommended 1
- For suspected community-acquired MRSA, add vancomycin or linezolid to the regimen 1
Special Considerations
Drug Resistance
- In regions with high rates (>25%) of macrolide-resistant S. pneumoniae, avoid macrolide monotherapy even in otherwise healthy patients 1, 2
- Levofloxacin has been shown to be effective against macrolide-resistant S. pneumoniae 4
- Recent antibiotic use increases the risk of drug-resistant pathogens; select an agent from a different class than what was recently used 1, 2
Treatment Duration
- Standard duration of therapy is generally 5-7 days for uncomplicated CAP 2
- Treatment should generally not exceed 8 days in a responding patient 1
Administration Timing
- For hospitalized patients, the first antibiotic dose should be administered while still in the emergency department 1, 2
- Antibiotic treatment should be initiated immediately after diagnosis of CAP 1
IV to Oral Switch
- Hospitalized patients may be switched from intravenous to oral antibiotics after they show clinical improvement, are hemodynamically stable, and can tolerate oral medications 3
Pitfalls to Avoid
- Avoid macrolide monotherapy in areas with high resistance rates or in patients with comorbidities 1, 2
- Avoid delayed antibiotic administration in hospitalized patients as this can increase mortality risk 2
- Don't overlook the possibility of atypical pathogens (Mycoplasma, Chlamydophila, Legionella) when selecting empiric therapy 5
- Be cautious with fluoroquinolone use in patients with risk factors for prolonged QT interval or tendon disorders 3
- Consider local resistance patterns when selecting empiric therapy, as these can vary significantly by region 1