How should I manage an otherwise healthy adult with community‑acquired pneumonia who meets outpatient criteria (CURB‑65 (Confusion, Urea, Respiratory rate, Blood pressure, age ≥ 65) score 0‑1, no significant comorbidities, stable vital signs, able to take oral medication)?

Management of Community-Acquired Pneumonia in an Otherwise Healthy Adult Meeting Outpatient Criteria

First-Line Antibiotic Selection

For an otherwise healthy adult with community-acquired pneumonia who meets outpatient criteria (CURB-65 score 0-1, no significant comorbidities, stable vital signs, able to take oral medication), prescribe amoxicillin 1 g orally three times daily for 5–7 days as the preferred first-line therapy. 1

• Amoxicillin retains in-vitro activity against approximately 90–95% of Streptococcus pneumoniae isolates, including many penicillin-resistant strains, making it the most effective oral agent for the predominant bacterial pathogen in CAP. 1
• High-dose amoxicillin (3–4 g per day) provides superior pneumococcal coverage compared with oral cephalosporins and is endorsed by both European respiratory societies and the U.S. Centers for Disease Control and Prevention as the standard empirical outpatient therapy for previously healthy adults. 1

Alternative Regimens When Amoxicillin Is Contraindicated

• Doxycycline 100 mg orally twice daily for 5–7 days is an acceptable alternative when amoxicillin cannot be used, offering reliable coverage of both typical bacterial pathogens (S. pneumoniae, H. influenzae, M. catarrhalis) and atypical organisms (Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila). 1

When to Avoid Macrolide Monotherapy

• Macrolide monotherapy (azithromycin or clarithromycin) should be avoided in most U.S. regions because pneumococcal macrolide resistance is 20–30%, exceeding the 25% threshold at which macrolides become unsafe as first-line agents. 1
• Macrolides should only be used when local S. pneumoniae macrolide resistance is documented to be <25%. 1

Agents to Avoid as First-Line Therapy

• Oral cephalosporins (e.g., cefuroxime, cefpodoxime) should not be used as first-line therapy because they show inferior in-vitro activity compared with high-dose amoxicillin, lack coverage of atypical pathogens, and are more costly without demonstrated clinical superiority. 1
• Fluoroquinolones should be reserved for patients with comorbidities or treatment failure, not used as first-line agents in uncomplicated outpatient pneumonia, due to FDA warnings about serious adverse events (tendon rupture, peripheral neuropathy, aortic dissection) and rising resistance. 1

Treatment Duration and Clinical Stability Criteria

• Treat for a minimum of 5 days and continue until the patient is afebrile for 48–72 hours with no more than one sign of clinical instability. 1
• The typical total course for uncomplicated CAP is 5–7 days. 1
• Clinical stability criteria include: temperature ≤37.8°C, heart rate ≤100 bpm, respiratory rate ≤24 breaths/min, systolic blood pressure ≥90 mmHg, oxygen saturation ≥90% on room air, ability to maintain oral intake, and normal mental status. 1

Monitoring and Follow-Up

• Arrange a clinical review at 48 hours (or sooner if symptoms worsen) to assess symptom resolution, oral intake, and treatment response. 1
• Indicators of treatment failure that warrant hospital referral include: no clinical improvement by day 2–3, development of respiratory distress (respiratory rate >30/min, oxygen saturation <92%), inability to tolerate oral antibiotics, or new complications such as pleural effusion. 1

Escalation Strategy for Treatment Failure

• If amoxicillin monotherapy fails, add or substitute a macrolide (azithromycin or clarithromycin) to provide coverage for atypical pathogens (Mycoplasma, Chlamydophila, Legionella). 1
• If combination therapy (β-lactam + macrolide/doxycycline) fails, switch to a respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily). 1

Long-Term Follow-Up

• Schedule a routine follow-up visit at 6 weeks; obtain a chest radiograph only if symptoms persist, physical signs remain abnormal, or the patient has high risk for underlying malignancy (e.g., smokers >50 years). 1

Prevention Measures

• Offer pneumococcal polysaccharide vaccination to all adults ≥65 years and those with high-risk conditions. 1
• Recommend annual influenza vaccination for all patients. 1
• Provide smoking-cessation counseling to every current smoker. 1

Critical Pitfalls to Avoid

• Never use macrolide monotherapy in regions where pneumococcal macrolide resistance exceeds 25% (the situation in most of the United States), as this leads to treatment failure and breakthrough bacteremia. 1
• Avoid indiscriminate fluoroquinolone use in uncomplicated outpatient CAP because of FDA warnings about serious adverse events in otherwise healthy adults and resistance concerns. 1
• Do not assume that all pneumonia cases require atypical coverage; in previously healthy adults without severe illness, amoxicillin or doxycycline monotherapy provides adequate empiric therapy, with atypical coverage added only if the initial regimen fails. 1