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

Treatment for Community-Acquired Pneumonia

The recommended first-line treatment for community-acquired pneumonia (CAP) is a combination of a β-lactam (such as amoxicillin or ceftriaxone) plus a macrolide (such as azithromycin or clarithromycin), with the specific regimen determined by severity and treatment setting. 1, 2

Treatment Based on Setting and Severity

Outpatient Treatment (Non-Severe CAP)

• For previously healthy outpatients with no risk factors for drug-resistant pathogens, a macrolide (azithromycin or clarithromycin) is recommended as first-line therapy 1
• Amoxicillin at higher doses is preferred for outpatient treatment according to British Thoracic Society guidelines 2
• Doxycycline 100 mg twice daily is an alternative first-line option for outpatients without comorbidities 1
• For outpatients with comorbidities or recent antibiotic use, a respiratory fluoroquinolone (levofloxacin) or a β-lactam plus a macrolide is recommended 1, 2

Non-Severe Inpatient Treatment

• Combined therapy with amoxicillin and a macrolide (erythromycin or clarithromycin) is preferred for patients requiring hospital admission 3, 2
• Most non-severe inpatients can be adequately treated with oral antibiotics when there are no contraindications to oral therapy 3
• A respiratory fluoroquinolone alone (levofloxacin) may provide a useful alternative for those intolerant of penicillins or macrolides 3, 4

Severe CAP/ICU Treatment

• Patients with severe pneumonia should be treated immediately after diagnosis with parenteral antibiotics 3
• An intravenous combination of a broad-spectrum β-lactamase stable antibiotic (co-amoxiclav, cefuroxime, cefotaxime, or ceftriaxone) together with a macrolide (clarithromycin or erythromycin) is preferred 3
• For patients with risk factors for Pseudomonas, use an antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin or levofloxacin 1, 2
• For suspected community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection, add vancomycin or linezolid 1, 2

Duration of Therapy

• Patients with CAP should be treated for a minimum of 5 days 3, 1
• Patients should be afebrile for 48–72 hours and have no more than 1 CAP-associated sign of clinical instability before discontinuation of therapy 3, 2
• For patients with severe microbiologically undefined pneumonia, 10 days of treatment is proposed 3
• Treatment should be extended to 14–21 days where Legionella, staphylococcal, or Gram-negative enteric bacilli pneumonia are suspected or confirmed 3

Switching from IV to Oral Therapy

• Patients should be switched from intravenous to oral therapy when they are hemodynamically stable and improving clinically 3, 2
• Patients should be able to ingest medications and have a normally functioning gastrointestinal tract 3, 2
• Patients initially treated with parenteral antibiotics should be transferred to an oral regimen as soon as clinical improvement occurs and temperature has been normal for 24 hours 1

Pathogen-Directed Therapy

• Once the etiology of CAP has been identified using reliable microbiological methods, antimicrobial therapy should be directed at that specific pathogen 3, 1
• For patients who fail to improve as expected, there should be a careful review by an experienced clinician of the clinical history, examination, prescription chart, and results of all available investigation results 3

Special Considerations

• For patients with hypoxemia or respiratory distress, a cautious trial of noninvasive ventilation is recommended unless immediate intubation is required due to severe hypoxemia 2
• Low-tidal-volume ventilation (6 cm³/kg of ideal body weight) should be used for patients undergoing ventilation who have diffuse bilateral pneumonia or acute respiratory distress syndrome 3, 2
• For patients admitted through the emergency department, the first antibiotic dose should be administered while still in the ED 3, 1

Common Pitfalls and Caveats

• Overreliance on fluoroquinolones can lead to resistance, and they should be reserved for patients with β-lactam allergies or when specifically indicated 1, 5
• Inadequate coverage for atypical pathogens should be avoided, ensuring coverage for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila 1, 4
• Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy 1, 5
• Delaying antibiotic administration is associated with increased mortality, particularly in severe pneumonia 2, 6

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, 2
• 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 (especially smokers and those over 50 years) 3, 2