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

Treatment for Community-Acquired Pneumonia

Outpatient Treatment (Previously Healthy, No Risk Factors)

For previously healthy outpatients without comorbidities or risk factors for drug-resistant pathogens, use either a macrolide (azithromycin or clarithromycin) or high-dose amoxicillin (1 g every 8 hours) as first-line monotherapy. 1, 2

• Azithromycin dosing: 500 mg on Day 1, followed by 250 mg once daily on Days 2-5 3
• Doxycycline 100 mg twice daily is an acceptable alternative, with the first dose at 200 mg to achieve adequate serum levels more rapidly 2
• The British Thoracic Society specifically recommends amoxicillin at higher doses for outpatient treatment 1

Outpatient Treatment (With Comorbidities or Recent Antibiotic Use)

For outpatients with comorbidities (diabetes, heart disease, lung disease, immunosuppression) or recent antibiotic exposure, use either a respiratory fluoroquinolone (levofloxacin or moxifloxacin) OR a β-lactam plus macrolide combination. 1, 2

• Levofloxacin 750 mg once daily is FDA-approved for CAP treatment 4
• Patients with recent exposure to one antibiotic class should receive treatment from a different class due to increased bacterial resistance risk 2
• Despite FDA warnings about fluoroquinolone adverse events, they remain justified in this population due to excellent performance, low resistance rates, coverage of typical and atypical organisms, oral bioavailability, and convenience of monotherapy 2

Hospitalized Non-ICU Patients

For hospitalized non-ICU patients, use a β-lactam (ceftriaxone or ampicillin-sulbactam) plus a macrolide (azithromycin or clarithromycin) as the preferred regimen. 1, 2, 5

• This combination provides coverage for both typical bacterial pathogens (including Streptococcus pneumoniae) and atypical organisms (Mycoplasma, Chlamydophila, Legionella) 2
• A respiratory fluoroquinolone alone (levofloxacin or moxifloxacin) can be used as an alternative 2
• The first antibiotic dose should be administered while still in the emergency department, as early administration is associated with improved outcomes 2
• Recent high-quality evidence from JAMA confirms that hospitalized patients without risk factors for resistant bacteria should receive β-lactam/macrolide combination therapy, such as ceftriaxone combined with azithromycin 5

Severe CAP/ICU Patients

For ICU patients without Pseudomonas risk factors, use a β-lactam (ceftriaxone, cefotaxime, or ampicillin-sulbactam) plus either azithromycin OR a respiratory fluoroquinolone (levofloxacin or moxifloxacin). 1, 2

Pseudomonas Risk Factors Present

For patients with risk factors for Pseudomonas aeruginosa (structural lung disease, recent hospitalization, recent broad-spectrum antibiotics), use an antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS either:

• Ciprofloxacin or levofloxacin (750 mg), OR 2
• An aminoglycoside (gentamicin, tobramycin, or amikacin) plus azithromycin 2

MRSA Considerations

Add vancomycin or linezolid when community-acquired MRSA is suspected, particularly with risk factors including prior MRSA infection, recent hospitalization, or recent antibiotic use. 2

• Systemic corticosteroid administration within 24 hours of severe CAP development may reduce 28-day mortality 5

Duration of Therapy

Treat CAP for a minimum of 5 days, ensuring the patient is afebrile for 48-72 hours and has no more than one CAP-associated sign of clinical instability before discontinuation. 1, 2

• For uncomplicated S. pneumoniae pneumonia, 7-10 days is typically sufficient 2
• For severe pneumonia or specific pathogens (Legionella, staphylococcal, Gram-negative enteric bacilli), extend treatment to 14-21 days 2
• Treatment generally should not exceed 8 days in a responding patient 2
• Levofloxacin is FDA-approved for both 5-day and 7-14 day regimens depending on severity 4

Switching from IV to Oral Therapy

Switch from intravenous to oral therapy when patients are hemodynamically stable, clinically improving, and have been afebrile for 24 hours. 1, 2

• The oral route is recommended for non-severe pneumonia when there are no contraindications 2
• Switching to oral therapy facilitates earlier hospital discharge and is cost-effective 2

Pathogen-Directed Therapy

Once the etiology of CAP is identified using reliable microbiological methods, narrow antimicrobial therapy to target the specific pathogen. 1, 2

• All patients should be tested for COVID-19 and influenza when these viruses are common in the community, as their diagnosis affects treatment and infection prevention strategies 5
• Only 38% of hospitalized CAP patients have a pathogen identified; of those, up to 40% have viruses and approximately 15% have S. pneumoniae 5
• Local antimicrobial susceptibility patterns should guide empiric therapy choices, as resistance patterns vary by region 2

Common Pitfalls to Avoid

• Overreliance on fluoroquinolones can lead to resistance; reserve them for patients with β-lactam allergies or when specifically indicated 2
• Inadequate atypical coverage is a critical error; ensure coverage for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila 2
• Failure to adjust therapy based on culture results leads to unnecessary prolonged therapy and promotes resistance 2
• Delaying antibiotic administration is associated with increased mortality, particularly in severe pneumonia 2

Follow-up

Clinical review should be arranged for all patients at approximately 6 weeks, either with their general practitioner or in a hospital clinic. 1

• For patients who fail to improve as expected, conduct careful review of clinical history, examination, and investigations 2
• Consider repeat chest radiograph, CRP, white cell count, and further microbiological testing 2