What is the initial treatment approach for pneumonia in adults?

Initial Treatment Approach for Pneumonia in Adults

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

Assessment of Severity and Treatment Setting

• Determine the appropriate setting for treatment (outpatient vs. inpatient) using validated severity assessment tools 2, 1
• Consider the presence of comorbidities, risk factors for drug-resistant pathogens, and severity of illness at presentation 2
• The Pneumonia Severity Index (PORT) can help identify low-risk patients who may be safely treated as outpatients 3

Outpatient Treatment

For healthy adults without comorbidities:

• First choice: Amoxicillin 1 g three times daily 1
• Alternatives:
  • Doxycycline 100 mg twice daily 1
  • Macrolides (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily) - only in areas with pneumococcal resistance to macrolides <25% 1

For adults with comorbidities:

• Combination therapy with:
  • 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 (azithromycin 500 mg on first day then 250 mg daily, clarithromycin 500 mg twice daily) or doxycycline 100 mg twice daily 1

Inpatient Treatment (Non-ICU)

• Preferred regimen: β-lactam (ampicillin/sulbactam, cefotaxime, ceftriaxone, or ceftaroline) PLUS a macrolide (azithromycin or clarithromycin) 1, 4
• Alternative: Respiratory fluoroquinolone alone (levofloxacin, moxifloxacin) 1, 5
• Antibiotics should be administered as soon as possible, preferably while the patient is still in the emergency department 2, 1

Severe CAP Requiring ICU Care

Without risk factors for Pseudomonas aeruginosa:

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

With risk factors for Pseudomonas aeruginosa:

• Antipseudomonal β-lactam (cefepime, ceftazidime, piperacillin-tazobactam, meropenem) PLUS either:
  • Ciprofloxacin OR
  • A macrolide plus aminoglycoside (gentamicin, tobramycin, or amikacin) 1

For MRSA risk factors:

• Add vancomycin or linezolid to the regimen 2, 1

Duration of Therapy

• Patients should be treated for a minimum of 5 days 2, 1
• Should be afebrile for 48-72 hours and have no more than 1 CAP-associated sign of clinical instability before discontinuation of therapy 2
• Longer duration may be needed if initial therapy was not active against the identified pathogen or if complicated by extrapulmonary infection 2

Switch from IV to Oral Therapy

• Patients should be switched from intravenous to oral therapy when they are:
  • Hemodynamically stable and improving clinically
  • Able to ingest medications
  • Have a normally functioning gastrointestinal tract 2
• Patients can be discharged once clinically stable with no other active medical problems and a safe environment for continued care 2

Special Considerations

• For suspected or confirmed influenza pneumonia, add oseltamivir 2
• For suspected H5N1 infection, treat with oseltamivir and antibacterial agents targeting S. pneumoniae and S. aureus 2
• Corticosteroid administration within 24 hours of development of severe CAP may reduce 28-day mortality 4

Common Pitfalls to Avoid

• Delayed antibiotic administration can increase mortality 1
• Overuse of fluoroquinolones should be avoided to prevent development of resistance 1
• Inadequate coverage of causative pathogens is associated with worse outcomes 1
• Relying solely on clinical presentation without radiographic confirmation can lead to misdiagnosis 4, 6
• Failure to recognize the need for hospitalization in patients with comorbidities, even if they appear to be at low risk based on severity scores 7