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

Treatment of Community-Acquired Pneumonia

The treatment of community-acquired pneumonia (CAP) should be based on patient risk factors, severity of illness, and setting of care, with empiric antibiotic therapy tailored to cover the most likely pathogens while considering local resistance patterns. 1

Initial Assessment and Treatment Approach

• Severity assessment should guide the decision between outpatient versus inpatient treatment, using tools like CURB-65 or the Pneumonia Severity Index (PSI) 2, 3
• The initial site of treatment should follow a 3-step process: (1) assessment of preexisting conditions that compromise safety of home care; (2) calculation of the PSI with recommendation for home care for risk classes I, II, and III; and (3) clinical judgment 2
• For patients admitted through the emergency department, the first antibiotic dose should be administered while still in the ED to minimize time to treatment 3
• All admitted patients should receive their first dose of antibiotic therapy within 8 hours of arrival to the hospital 2

Outpatient Treatment

• For previously healthy adults without comorbidities or recent antibiotic use:

  • First choice: Amoxicillin 1 g three times daily 1
  • Alternative options: Doxycycline 100 mg twice daily or a macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily) 1, 2

• For adults with comorbidities (COPD, diabetes, renal or congestive heart failure, malignancy):

  • An advanced macrolide or a respiratory fluoroquinolone 2, 3
  • Combination therapy options: Amoxicillin/clavulanate (500/125 mg three times daily, 875/125 mg twice daily, or 2000/125 mg twice daily) OR a cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily) PLUS a macrolide or doxycycline 1

• For suspected aspiration with infection:

  • Amoxicillin-clavulanate or clindamycin 2, 3

Non-Severe Inpatient Treatment (Medical Ward)

• Preferred regimen: β-lactam (ampicillin/sulbactam, cefotaxime, ceftriaxone, or ceftaroline) PLUS a macrolide (azithromycin or clarithromycin) 1, 2
• Alternative option: A respiratory fluoroquinolone alone (levofloxacin, moxifloxacin) 1, 2
• Most non-severe inpatients can be adequately treated with oral antibiotics when clinically appropriate 3

Severe CAP Requiring ICU Care

• For patients without risk factors for Pseudomonas aeruginosa:

  • Non-antipseudomonal β-lactam (ceftriaxone, cefotaxime) PLUS either a macrolide or a respiratory fluoroquinolone 1, 2

• For patients with risk factors for Pseudomonas aeruginosa:

  • Antipseudomonal β-lactam (cefepime, ceftazidime, piperacillin-tazobactam, meropenem) PLUS either ciprofloxacin OR a macrolide plus aminoglycoside 1, 2

• For patients with MRSA risk factors:

  • Add MRSA coverage (vancomycin or linezolid) and obtain cultures/nasal PCR to allow de-escalation 1

Duration of Therapy and Transition to Oral Therapy

• The duration of therapy is generally 5-7 days for responding patients 1, 4
• Patients should be switched from intravenous to oral therapy when they are hemodynamically stable and improving clinically 3
• Criteria for switch to oral therapy include: improvement in cough and dyspnea, afebrile (<100°F) on two occasions 8 hours apart, decreasing white blood cell count, and functioning gastrointestinal tract with adequate oral intake 2, 3
• Even if the patient is still febrile, switch therapy can occur if other clinical features are favorable 2

Special Considerations

• For suspected or confirmed Legionella, treatment options include respiratory fluoroquinolone (levofloxacin preferred) or macrolide (azithromycin preferred) 1
• For Mycoplasma or Chlamydophila, treatment options include macrolide, doxycycline, or respiratory fluoroquinolone 1
• Systemic corticosteroid administration within 24 hours of development of severe CAP may reduce 28-day mortality 4

Common Pitfalls and Caveats

• Delayed antibiotic administration can increase mortality; ensure timely administration 1
• Overuse of fluoroquinolones should be avoided to prevent development of resistance 1, 5
• Azithromycin carries risks of QT prolongation, which can be fatal in at-risk groups including patients with known QT prolongation, history of torsades de pointes, congenital long QT syndrome, or uncompensated heart failure 6
• Inadequate coverage of causative pathogens is associated with worse outcomes 1
• For patients who fail to improve as expected, conduct a careful review of the clinical history, examination, prescription chart, and results of all available investigations 3
• Up to 10% of all CAP patients will not respond to initial therapy, requiring diagnostic evaluation for drug-resistant or unusual pathogens, nonpneumonia diagnoses, or pneumonia complications 2

Follow-up

• Clinical review should be arranged for all patients at around 6 weeks, either with their general practitioner or in a hospital clinic 3
• A chest radiograph should be arranged at follow-up for patients with persistent symptoms or physical signs, or who are at higher risk of underlying malignancy 3
• Pneumonia can be prevented by pneumococcal and influenza vaccines in appropriate at-risk populations 2