What is the recommended treatment for community-acquired pneumonia (CAP) in an inpatient setting?

Treatment of Community-Acquired Pneumonia in Inpatient Settings

For hospitalized non-ICU patients with community-acquired pneumonia (CAP), the recommended empiric treatment is a β-lactam (such as ceftriaxone, cefotaxime, ampicillin-sulbactam, or ceftaroline) plus a macrolide (such as azithromycin), or alternatively, a respiratory fluoroquinolone alone. 1, 2

Standard Treatment Regimens for Hospitalized Non-ICU Patients

Combination Therapy (Preferred):

• β-lactam plus macrolide combination:
  • β-lactam options: ampicillin-sulbactam 1.5-3g IV every 6 hours, cefotaxime 1-2g IV every 8 hours, ceftriaxone 1-2g IV daily, or ceftaroline 600mg IV every 12 hours 1
  • Plus a macrolide: azithromycin 500mg IV daily for at least 2 days, then 500mg orally daily to complete a 7-10 day course 2, 3

Monotherapy Alternative:

• Respiratory fluoroquinolone: levofloxacin 750mg IV/oral daily or moxifloxacin 400mg IV/oral daily 1, 2

Treatment for ICU Patients

For ICU Patients without Risk Factors for Pseudomonas:

• β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either:
  • Azithromycin 500mg IV daily, or
  • A respiratory fluoroquinolone (levofloxacin 750mg or moxifloxacin 400mg) 1, 2

For ICU Patients with Risk Factors for Pseudomonas:

• Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either:
  • Ciprofloxacin or levofloxacin (750mg), or
  • An aminoglycoside plus azithromycin 1, 2

Special Considerations

MRSA Coverage:

• Add vancomycin or linezolid when community-acquired MRSA is suspected 2
• Risk factors include prior MRSA infection, recent hospitalization, or recent antibiotic use 2

Timing of Administration:

• First antibiotic dose should be administered while the patient is still in the emergency department 2, 4
• Early administration is associated with improved outcomes and reduced mortality 2

Duration of Therapy:

• Minimum duration of 5 days for most patients 2
• Patient should be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuing therapy 2
• For uncomplicated S. pneumoniae pneumonia, 7-10 days is typically sufficient 2
• For severe pneumonia or specific pathogens like Legionella or staphylococcal infections, extend treatment to 14-21 days 2

Switching from IV to Oral Therapy:

• Transfer to oral regimen as soon as clinical improvement occurs and temperature has been normal for 24 hours 2
• For azithromycin, switch from IV to oral at physician's discretion based on clinical response 3

Clinical Rationale and Evidence

• Combination therapy with a β-lactam plus macrolide has been associated with lower mortality than monotherapy in bacteremic pneumococcal pneumonia 1
• The benefit of combination therapy is most pronounced in patients with severe illness 1
• Macrolides provide coverage for atypical pathogens (Mycoplasma, Chlamydophila, Legionella) and may have anti-inflammatory effects 5
• Respiratory fluoroquinolones offer the advantage of covering both typical and atypical pathogens as monotherapy 6

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 2
• Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy 2
• Delaying antibiotic administration is associated with increased mortality, particularly in severe pneumonia 2, 4
• For patients who fail to improve as expected, conduct a careful review of the clinical history, examination, and consider additional investigations 2

Specific Dosing for Azithromycin in CAP

• For inpatient treatment: 500mg IV as a single daily dose for at least 2 days 3
• Follow IV therapy with oral azithromycin 500mg daily to complete a 7-10 day course 3
• Infuse at a concentration of either 1mg/mL over 3 hours or 2mg/mL over 1 hour 3
• Do not administer as a bolus or intramuscular injection 3