What are the initial treatment recommendations for Community-Acquired Pneumonia (CAP)?

Community-Acquired Pneumonia Treatment

For hospitalized non-ICU patients with CAP, the recommended first-line therapy is a β-lactam (such as ceftriaxone) combined with a macrolide (such as azithromycin), administered for a minimum of 5 days, with patients requiring 48-72 hours afebrile before discontinuation. 1, 2

Treatment Algorithm by Clinical Setting

Outpatient Treatment (Previously Healthy, No Comorbidities)

• First-line options include amoxicillin 1 g every 8 hours or doxycycline 100 mg twice daily (with a 200 mg loading dose). 1
• A macrolide (azithromycin or clarithromycin) is an alternative first-line choice, providing coverage against typical and atypical organisms including Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila. 1, 2

Outpatient Treatment (With Comorbidities or Recent Antibiotic Use)

• Use either a respiratory fluoroquinolone (levofloxacin or moxifloxacin) OR a β-lactam plus a macrolide. 1, 2
• Patients with recent exposure to one antibiotic class should receive treatment from a different class due to increased resistance risk. 1
• Despite FDA warnings about fluoroquinolone adverse events, these agents remain justified for patients with comorbidities due to their broad coverage, low resistance rates, and convenience of monotherapy. 1

Hospitalized Non-ICU Patients

• The preferred regimen is a β-lactam (ceftriaxone) plus a macrolide (azithromycin or clarithromycin). 1, 2, 3
• An alternative is respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily or moxifloxacin 400 mg daily). 1, 2
• Penicillin G plus a macrolide is another acceptable option. 1
• The first antibiotic dose should be administered in the emergency department, as early administration is associated with improved outcomes and reduced mortality. 1

Severe CAP/ICU Patients (Without Pseudomonas Risk)

• Administer a β-lactam plus either a macrolide OR a respiratory fluoroquinolone. 1, 2
• Moxifloxacin or levofloxacin plus a non-antipseudomonal third-generation cephalosporin is an alternative regimen. 1

Severe CAP/ICU Patients (With Pseudomonas Risk Factors)

• Use an antipseudomonal β-lactam PLUS either ciprofloxacin or levofloxacin. 1
• Alternative: antipseudomonal β-lactam plus aminoglycoside (gentamicin, tobramycin, or amikacin) plus azithromycin. 1
• Alternative: antipseudomonal β-lactam plus aminoglycoside plus an antipneumococcal fluoroquinolone. 1

Duration of Therapy

• Minimum treatment duration is 5 days for most patients. 1, 2
• Patients must be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuing therapy. 1, 2
• For uncomplicated S. pneumoniae pneumonia, 7-10 days is typically sufficient. 1
• For severe pneumonia or when Legionella, staphylococcal, or Gram-negative enteric bacilli are suspected, extend treatment to 14-21 days. 1
• Treatment generally should not exceed 8 days in a responding patient. 1

Switching from IV to Oral Therapy

• Switch from intravenous to oral therapy when patients are hemodynamically stable, clinically improving, and afebrile for 24 hours. 1, 2
• The oral route is recommended for non-severe pneumonia when there are no contraindications. 1

Special Considerations

MRSA Coverage

• Add vancomycin or linezolid when community-acquired MRSA is suspected. 1
• Risk factors include prior MRSA infection, recent hospitalization, or recent antibiotic use. 1

Pathogen-Directed Therapy

• Once etiology is identified through reliable microbiological methods, narrow antimicrobial therapy to target the specific pathogen. 1, 2
• Culture and susceptibility testing should be performed before treatment when possible. 4
• Local antimicrobial susceptibility patterns should guide empiric therapy choices, as resistance patterns vary by region. 1

Severe Pneumonia Management

• For patients with diffuse bilateral pneumonia or acute respiratory distress syndrome requiring ventilation, use low-tidal-volume ventilation (6 mL/kg ideal body weight). 2
• Systemic corticosteroid administration within 24 hours of severe CAP development may reduce 28-day mortality. 3

Common Pitfalls and Caveats

• Avoid overreliance on fluoroquinolones, which can lead to resistance; reserve them for patients with β-lactam allergies or specific indications. 1
• Ensure adequate coverage for atypical pathogens (Mycoplasma, Chlamydophila, Legionella), as clinical success is significantly higher for Legionella when atypical coverage is included. 1, 5
• Failure to adjust therapy based on culture results leads to unnecessary prolonged therapy. 1
• Test all patients for COVID-19 and influenza when these viruses are common in the community, as diagnosis affects treatment and infection prevention strategies. 3
• Delaying antibiotic administration is associated with increased mortality, particularly in severe pneumonia. 1

Follow-up

• Clinical review should be arranged for all patients at approximately 6 weeks, either with their general practitioner or in a hospital clinic. 2
• For patients who fail to improve as expected, conduct careful review of clinical history, examination, and investigations; consider repeat chest radiograph, CRP, white cell count, and further microbiological testing. 1