What is the recommended treatment for community-acquired pneumonia (CAP)?

Treatment for Community-Acquired Pneumonia

The recommended treatment for community-acquired pneumonia (CAP) should be based on the patient's setting (outpatient vs. inpatient), comorbidities, and risk factors, with specific antibiotic regimens tailored to each scenario. 1, 2

Outpatient Treatment

For Previously Healthy Outpatients (No Comorbidities):

• Amoxicillin 1 g orally every 8 hours 1, 2
• OR Doxycycline 100 mg orally twice daily (consider 200 mg for first dose to achieve adequate serum levels more rapidly) 1, 2

For Outpatients with Comorbidities or Recent Antibiotic Use:

• A respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1, 2, 3
• OR A β-lactam plus a macrolide (amoxicillin 1 g every 8 hours plus azithromycin 500 mg on day 1, then 250 mg daily for days 2-5) 1, 2, 4

Important Considerations for Outpatient Treatment:

• Patients with recent exposure to one antibiotic class should receive treatment with antibiotics from a different class due to increased risk of bacterial resistance 1
• Despite concerns about adverse events with fluoroquinolones, they remain justified for adults with comorbidities due to their broad coverage, low resistance rates, and convenience of monotherapy 1, 5
• Be aware of increasing reports of adverse events related to fluoroquinolone use as noted by the FDA 1, 3

Inpatient Treatment (Non-ICU)

Recommended Regimens:

• Combination therapy with a β-lactam (ampicillin-sulbactam 1.5-3 g every 6 hours, cefotaxime 1-2 g every 8 hours, ceftriaxone 1-2 g daily, or ceftaroline 600 mg every 12 hours) plus a macrolide (azithromycin 500 mg daily or clarithromycin 500 mg twice daily) 1, 2, 6
• OR Monotherapy with a respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1, 2
• For patients with contraindications to both macrolides and fluoroquinolones: combination therapy with a β-lactam plus doxycycline 100 mg twice daily 1, 2

Severe CAP/ICU Treatment

For Patients Without Risk Factors for Pseudomonas:

• A β-lactam plus either a macrolide or a respiratory fluoroquinolone 2

For Patients With Risk Factors for Pseudomonas:

• An antipseudomonal β-lactam plus either ciprofloxacin/levofloxacin OR an aminoglycoside plus azithromycin OR an aminoglycoside plus an antipneumococcal fluoroquinolone 2

For Suspected MRSA:

• Add vancomycin or linezolid when community-acquired MRSA is suspected (risk factors include prior MRSA infection, recent hospitalization, or recent antibiotic use) 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 severe pneumonia or when specific pathogens like Legionella, staphylococcal, or gram-negative enteric bacilli are suspected or confirmed, extend treatment to 14-21 days 2

Timing of Antibiotic Administration

• For hospitalized patients, the first antibiotic dose should be administered while still in the emergency department 2
• Early administration is associated with improved outcomes 2, 6

Special Considerations

• For patients who fail to improve as expected, conduct a careful review of the clinical history, examination, prescription chart, and all available investigation results 2
• Consider additional investigations including repeat chest radiograph, CRP, white cell count, and further microbiological testing 2
• Local antimicrobial susceptibility patterns should guide the choice of empiric therapy, as resistance patterns may vary by region 2

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 (Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila) should be avoided 2
• Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy; antimicrobial therapy should be directed at the specific pathogen once identified 2
• Delaying antibiotic administration is associated with increased mortality, particularly in severe pneumonia 2, 6