Treatment for Hospitalized Community-Acquired Pneumonia
For patients hospitalized with community-acquired pneumonia on a medical ward, initiate empiric therapy with a beta-lactam (ceftriaxone, cefotaxime, or ampicillin-sulbactam) combined with a macrolide (azithromycin or clarithromycin), or alternatively use a respiratory fluoroquinolone (levofloxacin or moxifloxacin) as monotherapy. 1
Severity-Based Treatment Algorithm
Non-ICU Hospitalized Patients (Medical Ward)
Preferred regimens:
- Beta-lactam + Macrolide combination: Ceftriaxone 1-2g IV daily (or cefotaxime 1-2g IV q8h) PLUS azithromycin 500mg IV/PO daily 1
- Respiratory fluoroquinolone monotherapy: Levofloxacin 750mg IV/PO daily OR moxifloxacin 400mg IV/PO daily 1, 2
The combination therapy approach provides coverage for both typical pathogens (particularly Streptococcus pneumoniae) and atypical organisms (Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila) 1, 3. While some evidence questions the universal need for atypical coverage, current guidelines maintain this recommendation based on observational data showing improved outcomes 4, 5.
ICU-Admitted Patients (Severe CAP)
For patients WITHOUT Pseudomonas risk factors:
- Beta-lactam (ceftriaxone 2g IV daily, cefotaxime 2g IV q8h, or ampicillin-sulbactam 3g IV q6h) PLUS either azithromycin 500mg IV daily OR a respiratory fluoroquinolone 1
For patients WITH Pseudomonas risk factors:
- Antipseudomonal beta-lactam (piperacillin-tazobactam 4.5g IV q6h, cefepime 2g IV q8h, imipenem 500mg IV q6h, or meropenem 1g IV q8h) PLUS ciprofloxacin 400mg IV q8h OR PLUS aminoglycoside (gentamicin 5-7mg/kg IV daily) plus azithromycin or respiratory fluoroquinolone 1
Risk factors for Pseudomonas include: severe structural lung disease (bronchiectasis), recent antibiotic therapy within 90 days, recent hospitalization, or ICU admission 1.
Critical Timing Considerations
Administer the first antibiotic dose within 8 hours of hospital arrival, ideally while still in the emergency department 1. This timing has been associated with reduced 30-day mortality in hospitalized CAP patients 1.
Pathogen-Specific Coverage Nuances
Drug-Resistant Streptococcus pneumoniae (DRSP)
For patients with risk factors for DRSP (age ≥65 years, beta-lactam use within 3 months, alcoholism, multiple comorbidities, immunosuppression), the recommended beta-lactams are limited to high-dose amoxicillin, amoxicillin-clavulanate, cefpodoxime, cefuroxime (oral) or ceftriaxone, cefotaxime, ampicillin-sulbactam (IV) 1. Levofloxacin has demonstrated 95% clinical and bacteriologic success against multi-drug resistant S. pneumoniae 2.
Atypical Pathogen Coverage
The macrolide component or fluoroquinolone provides essential coverage for Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae 1, 6. Clinical success rates for atypical pathogens with levofloxacin were 96% for M. pneumoniae and C. pneumoniae, and 70% for L. pneumophila 2.
Important Caveats
Do not use fluoroquinolone monotherapy in ICU patients—always combine with a beta-lactam for severe CAP 1. Current data do not support fluoroquinolone monotherapy in this critically ill population.
Avoid using two beta-lactams simultaneously when dual therapy is required for high-risk patients 1.
Consider MRSA coverage (vancomycin 15mg/kg IV q8-12h targeting trough 15-20 mcg/mL, or linezolid 600mg IV q12h) if the patient has received IV antibiotics within 90 days, is in a unit where >20% of S. aureus isolates are methicillin-resistant, or has high mortality risk (requiring ventilatory support or septic shock) 1.
Transition to Oral Therapy and Duration
Switch from IV to oral therapy when: the patient is hemodynamically stable, clinically improving, afebrile for 48-72 hours on two occasions 8 hours apart, able to ingest medications, and has normal gastrointestinal function 1. Patients can be discharged the same day as oral transition if medically and socially appropriate 1.
Minimum treatment duration is 5 days with the patient being afebrile for 48-72 hours and having no more than one CAP-associated sign of clinical instability before discontinuation 1. Most patients should not receive more than 8 days of therapy if responding appropriately 1.
Diagnostic Testing Considerations
Obtain before initiating antibiotics: two sets of blood cultures, sputum Gram stain and culture (if adequate specimen available), and urinary antigen testing for Legionella pneumophila serogroup 1 if clinically or epidemiologically suspected 1. Test all patients for COVID-19 and influenza when these viruses are circulating in the community, as results may alter management 3.