Community-Acquired Pneumonia: Outpatient Treatment
First-Line Treatment for Healthy Adults Without Comorbidities
Amoxicillin 1 g orally three times daily for 5-7 days is the preferred first-line therapy for previously healthy outpatients with community-acquired pneumonia. 1
- This recommendation is based on amoxicillin's effectiveness against Streptococcus pneumoniae (the most common CAP pathogen), excellent safety profile, and high-dose targeting of ≥93% of S. pneumoniae strains including drug-resistant isolates 1
- Doxycycline 100 mg orally twice daily serves as an acceptable alternative for patients who cannot tolerate amoxicillin, though this carries lower quality evidence 1
- Macrolides (azithromycin 500 mg day 1, then 250 mg daily for days 2-5, or clarithromycin 500 mg twice daily) should only be used when local pneumococcal macrolide resistance is documented to be <25% 1, 2
Treatment for Outpatients With Comorbidities
For patients with comorbidities (COPD, diabetes, chronic heart/liver/renal disease, malignancy) or recent antibiotic use within 3 months, use combination therapy with a β-lactam plus macrolide or respiratory fluoroquinolone monotherapy. 1
Combination Therapy Option:
- Amoxicillin-clavulanate 875 mg/125 mg orally twice daily (or high-dose 2,000 mg/125 mg twice daily) PLUS azithromycin 500 mg day 1, then 250 mg daily for days 2-5 3, 1, 2
- Alternative β-lactams include cefpodoxime or cefuroxime, though these have inferior in vitro activity compared to high-dose amoxicillin 1
Fluoroquinolone Monotherapy Option:
- Levofloxacin 750 mg orally daily for 5 days OR moxifloxacin 400 mg orally daily for 5 days 3, 1
- However, fluoroquinolone use should be discouraged in uncomplicated cases due to FDA warnings about serious adverse events (tendon rupture, peripheral neuropathy, aortic dissection) and resistance concerns 1, 2
Critical Pitfalls to Avoid in Outpatient Management
- Never use macrolide monotherapy in areas where pneumococcal macrolide resistance exceeds 25%, as this leads to treatment failure with resistant isolates 1
- Avoid indiscriminate fluoroquinolone use in uncomplicated outpatient CAP—reserve for patients with true β-lactam allergies or specific comorbidities 1
- If the patient received antibiotics within the past 90 days, select an agent from a different antibiotic class to reduce resistance risk 3, 1
- Avoid fluoroquinolones in patients with cardiac arrhythmias, QT prolongation, or vascular disease due to increased risk of serious cardiac events 3, 2
Duration of Therapy
Treat for a minimum of 5 days and until the patient is afebrile for 48-72 hours with no more than one sign of clinical instability. 1
- The typical duration for uncomplicated CAP is 5-7 days total 1
- Short-course treatment (≤6 days) has equivalent clinical cure rates with fewer adverse events compared to ≥7 days 1
When to Consider Hospitalization
Hospitalize patients in PSI risk classes IV-V, or those with any of the following: 1
- Hypoxemia (oxygen saturation <90% on room air)
- Multilobar infiltrates on chest radiograph
- Systolic blood pressure <90 mmHg
- Respiratory rate >30 breaths/minute
- Altered mental status
- Inability to take oral medications
- Significant comorbidities compromising ability to respond to illness (immunodeficiency, functional asplenia, cystic fibrosis) 2
Follow-Up Recommendations
- Clinical review at 48 hours or sooner if clinically worsening 1
- Schedule clinical review at 6 weeks for all patients, with chest radiograph reserved for those with persistent symptoms, physical signs, or high risk for underlying malignancy (smokers, age >50 years) 1
- Chest radiograph need not be repeated before discharge in patients with satisfactory clinical recovery 1
Special Population: Suspected Atypical Pathogens
For school-aged children and adolescents with clinical features suggesting atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae)—such as gradual onset, prominent cough, minimal fever—add macrolide coverage. 4, 5