What is the recommended treatment for community-acquired pneumonia?

Treatment of Community-Acquired Pneumonia

For hospitalized patients with community-acquired pneumonia, initiate combination therapy with a β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a respiratory fluoroquinolone immediately upon diagnosis. 1

Outpatient Management (Non-Severe CAP)

Previously healthy patients without comorbidities:

• First-line: Amoxicillin monotherapy 2, 3
• Alternative options include:
  • Doxycycline 2, 4
  • Macrolide (azithromycin or clarithromycin) - only in areas where pneumococcal macrolide resistance is <25% 2, 4
  • Respiratory fluoroquinolone (levofloxacin 500-750 mg daily or moxifloxacin) 2

Patients with comorbidities (chronic lung/heart/renal/liver disease, diabetes, immunosuppression):

• Combination therapy: β-lactam plus macrolide 3, 4
• Alternative: Respiratory fluoroquinolone monotherapy 4

Treatment duration: 5-7 days for uncomplicated cases 1, 2

Hospitalized Patients (Non-Severe CAP)

Preferred regimen:

• Oral combination: Amoxicillin plus macrolide (clarithromycin or azithromycin) 3
• When oral route contraindicated: IV ampicillin or benzylpenicillin plus IV erythromycin or clarithromycin 3

Alternative regimen:

• β-lactam (second or third generation cephalosporin) plus macrolide 1

Treatment duration: 7-10 days 1, 2

Critical timing consideration: Administer first antibiotic dose in the emergency department before admission 1

Severe CAP Requiring ICU Admission

Immediate parenteral combination therapy is mandatory:

• β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) PLUS azithromycin (level II evidence) OR fluoroquinolone (level I evidence) 1
• Alternative for β-lactam allergic patients: Respiratory fluoroquinolone plus aztreonam 1

Treatment duration: 10 days minimum 1

• Extend to 14-21 days for Legionella, Staphylococcus aureus, or Gram-negative enteric bacilli 1, 2

Special Pathogen Considerations in Severe CAP:

Pseudomonas aeruginosa risk factors present:

• Antipneumococcal, antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS ciprofloxacin or levofloxacin 750 mg 1
• Alternative: Above β-lactam plus aminoglycoside plus azithromycin 1

Community-acquired MRSA suspected:

• Add vancomycin or linezolid to standard regimen 1

Transition from IV to Oral Therapy

Switch criteria (all must be met):

• Hemodynamically stable 1, 3
• Clinically improving 1
• Afebrile for 24-48 hours 1, 3
• Able to ingest medications with normally functioning GI tract 1

Use sequential therapy with the same antibiotic class when possible 2

Discharge immediately once stable on oral therapy - inpatient observation while on oral antibiotics is unnecessary 1

Treatment Duration Optimization

Minimum criteria for discontinuation (all must be met):

• At least 5 days of therapy completed 1, 2
• Afebrile for 48-72 hours 1, 2
• No more than 1 CAP-associated sign of clinical instability 1

Do not routinely exceed 8 days in responding patients 2

Management of Treatment Failure (No Improvement by 48-72 Hours)

Immediate actions required:

• Experienced clinician review of history, examination, and all investigation results 1, 3
• Obtain repeat chest radiograph, CRP, white cell count, and additional microbiological specimens 1, 3

Antibiotic adjustment strategies:

For non-severe pneumonia on amoxicillin monotherapy:

• Add or substitute macrolide to cover atypical pathogens (Mycoplasma, Chlamydophila, Legionella) 1, 2, 3

For non-severe pneumonia on combination therapy:

• Switch to respiratory fluoroquinolone with pneumococcal coverage 1, 3

For severe pneumonia not responding to combination therapy:

• Consider adding rifampicin 1, 3

Critical Pitfalls to Avoid

Never delay antibiotics while awaiting diagnostic results - empiric therapy must begin immediately as this directly impacts mortality 2, 3

Do not use macrolide monotherapy in areas with pneumococcal macrolide resistance ≥25% 4

Do not continue the same regimen beyond 48-72 hours without reassessment if patient fails to improve 2, 3

Azithromycin carries risk of QT prolongation and torsades de pointes - avoid in patients with prolonged QT interval, bradyarrhythmias, uncompensated heart failure, or concurrent use of Class IA/III antiarrhythmics 5

For penicillin-allergic patients, never use β-lactams - substitute respiratory fluoroquinolone plus aztreonam for severe cases 1

Adjunctive Therapies for Severe CAP

Systemic corticosteroids within 24 hours may reduce 28-day mortality in severe CAP 6

Screen hypotensive, fluid-resuscitated patients for occult adrenal insufficiency 1

Consider noninvasive ventilation for hypoxemia/respiratory distress unless severe hypoxemia (PaO₂/FiO₂ <150) with bilateral infiltrates requires immediate intubation 1