What is the recommended treatment for Community-Acquired Pneumonia (CAP)?

Treatment of Community-Acquired Pneumonia (CAP)

For outpatients without comorbidities, use amoxicillin at high doses or a macrolide (azithromycin or clarithromycin); for hospitalized patients with non-severe CAP, use combination therapy with a β-lactam (amoxicillin or ceftriaxone) plus a macrolide (azithromycin or clarithromycin); for severe CAP requiring ICU admission, use a β-lactam plus either a macrolide or respiratory fluoroquinolone. 1, 2

Outpatient Treatment

Previously Healthy Patients (No Comorbidities)

• Amoxicillin at higher doses is the preferred first-line agent 1, 2
• Alternative: Macrolide monotherapy (azithromycin 500 mg day 1, then 250 mg daily days 2-5, or clarithromycin) 1, 3
• Macrolides are particularly appropriate for patients with penicillin allergies 2

Patients with Comorbidities or Recent Antibiotic Use

• Use combination therapy: β-lactam plus macrolide 1
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily) 1, 4
• Fluoroquinolones provide coverage for drug-resistant pathogens and have excellent lung penetration 5

Pre-Hospital Antibiotic Administration

• General practitioners should administer antibiotics immediately if the illness is life-threatening or if hospital admission delays exceed 2 hours 2

Non-Severe Inpatient Treatment

• Combined oral therapy with amoxicillin plus a macrolide (azithromycin or clarithromycin) is the standard regimen 1, 2
• Most non-severe inpatients can be adequately treated with oral antibiotics 2
• Respiratory fluoroquinolone (levofloxacin) is a useful alternative for patients intolerant of penicillins or macrolides 2
• For patients admitted through the emergency department, administer the first antibiotic dose while still in the ED to minimize time to treatment 6, 2

Severe Inpatient Treatment (ICU-Level Care)

Standard Empiric Regimen

• β-lactam (ceftriaxone, ampicillin-sulbactam) plus macrolide (azithromycin) 1, 2, 7
• Alternative: β-lactam plus respiratory fluoroquinolone 2
• Parenteral antibiotics should be initiated immediately after diagnosis 2

Special Pathogen Coverage

For Pseudomonas aeruginosa risk factors:

• Use an antipneumococcal, antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin or levofloxacin 750 mg 2

For community-acquired MRSA:

• Add vancomycin or linezolid to the standard regimen 2

Duration of Therapy

• Minimum treatment duration: 5 days 6, 1, 2
• Patients must be afebrile for 48-72 hours before discontinuation 6, 1, 2
• No more than 1 CAP-associated sign of clinical instability should be present at discontinuation 6, 2
• Longer duration may be needed if initial therapy was inactive against the identified pathogen or if complicated by extrapulmonary infection (meningitis, endocarditis) 6, 2

Switching from IV to Oral Therapy

• Switch when the patient is hemodynamically stable and clinically improving 6, 1, 2
• Patient must be able to ingest medications and have a normally functioning gastrointestinal tract 6, 2
• Inpatient observation while receiving oral therapy is not necessary—discharge when clinically stable 6

Pathogen-Directed Therapy

• Once etiology is identified through reliable microbiological methods, direct therapy at the specific pathogen 6, 1, 2
• Early treatment within 48 hours of symptom onset is recommended 6, 2

Adjunctive Therapies for Severe CAP

• Systemic corticosteroids administered within 24 hours may reduce 28-day mortality in severe CAP 7
• For patients with hypoxemia or respiratory distress, consider noninvasive ventilation unless severe hypoxemia (PaO₂/FiO₂ ratio <150) and bilateral infiltrates require immediate intubation 6, 2
• Use low-tidal-volume ventilation (6 mL/kg ideal body weight) for patients with diffuse bilateral pneumonia or ARDS 6, 1, 2

Testing and Diagnostic Considerations

• All patients should be tested for COVID-19 and influenza when these viruses are circulating in the community, as results may affect treatment and infection prevention strategies 7
• Only 38% of hospitalized CAP patients have a pathogen identified; empiric therapy covering typical and atypical pathogens is essential 7

Follow-Up

• Clinical review should be arranged at approximately 6 weeks with either the general practitioner or in a hospital clinic 1, 2
• Chest radiograph at follow-up is indicated for patients with persistent symptoms, physical signs, or higher risk of underlying malignancy (especially smokers and those over 50 years) 2

Common Pitfalls to Avoid

• Do not delay antibiotics in hospitalized patients—administer while still in the ED 6, 2
• Do not use macrolide monotherapy for severe CAP or patients with comorbidities 1, 2
• Do not continue IV antibiotics once the patient is stable and can tolerate oral therapy 6
• Do not treat for less than 5 days, even if the patient appears clinically improved 6, 1, 2