What is the recommended treatment for community‑acquired pneumonia in adults?

Treatment of Community-Acquired Pneumonia in Adults

For otherwise healthy outpatients without comorbidities, use amoxicillin 1g three times daily as first-line therapy; for patients with comorbidities (diabetes, chronic heart/lung/liver/renal disease, alcoholism, malignancy, asplenia), use combination therapy with amoxicillin-clavulanate plus a macrolide or monotherapy with a respiratory fluoroquinolone. 1

Outpatient Treatment

Healthy Adults Without Comorbidities

First-line monotherapy options include: 1

• Amoxicillin 1g three times daily (preferred, strong recommendation)
• Doxycycline 100mg twice daily (conditional recommendation)
• Macrolide monotherapy (azithromycin 500mg day 1, then 250mg daily; or clarithromycin 500mg twice daily) ONLY if local pneumococcal macrolide resistance is <25% 1

The 2019 ATS/IDSA guidelines represent a significant shift from prior recommendations by endorsing beta-lactam monotherapy (amoxicillin) as the preferred first-line agent for uncomplicated outpatient CAP, moving away from routine macrolide or fluoroquinolone use in this population. 1, 2

Patients With Comorbidities

For patients with diabetes, chronic heart/lung/liver/renal disease, alcoholism, malignancy, or asplenia, use: 1

Combination therapy (preferred):

• Amoxicillin-clavulanate (500mg/125mg three times daily, OR 875mg/125mg twice daily, OR 2000mg/125mg twice daily) PLUS
• Macrolide (azithromycin or clarithromycin at doses above) OR doxycycline 100mg twice daily

OR Monotherapy:

• Respiratory fluoroquinolone: levofloxacin 750mg daily, moxifloxacin 400mg daily, or gemifloxacin 320mg daily 1

Alternative beta-lactams for combination therapy include cefpodoxime 200mg twice daily or cefuroxime 500mg twice daily. 1

Inpatient Non-ICU Treatment

For hospitalized patients not requiring ICU admission, use either: 1

• Beta-lactam (ampicillin-sulbactam 1.5-3g every 6h, cefotaxime 1-2g every 8h, ceftriaxone 1-2g daily, or ceftaroline 600mg every 12h) PLUS macrolide (azithromycin 500mg daily or clarithromycin 500mg twice daily) (strong recommendation, high quality evidence)

OR

• Respiratory fluoroquinolone monotherapy (levofloxacin 750mg daily or moxifloxacin 400mg daily) (strong recommendation, high quality evidence) 1

For patients with contraindications to both macrolides and fluoroquinolones, use beta-lactam plus doxycycline 100mg twice daily. 1

Meta-analyses show similar clinical outcomes between beta-lactam/macrolide combination and fluoroquinolone monotherapy, though fluoroquinolones had fewer treatment discontinuations. However, combination therapy may offer mortality benefits in observational studies. 1

Severe CAP Requiring ICU Admission

For severe CAP, always use combination therapy: 1

• Beta-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam at doses above) PLUS azithromycin (strong recommendation) 1

OR

• Beta-lactam PLUS respiratory fluoroquinolone (levofloxacin 750mg daily or moxifloxacin 400mg daily) 1

Observational data from nearly 10,000 critically ill CAP patients demonstrated that macrolide-containing regimens reduced mortality by 18% relative risk (3% absolute risk reduction) compared to non-macrolide regimens. 1

Special Pathogen Coverage

For Pseudomonas aeruginosa risk factors (structural lung disease, recent broad-spectrum antibiotics, recent hospitalization): 1

• Antipseudomonal beta-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS
• Ciprofloxacin OR levofloxacin 750mg daily
• OR antipseudomonal beta-lactam PLUS aminoglycoside PLUS azithromycin or fluoroquinolone 1

For MRSA risk factors (prior MRSA infection, IV drug use, recent influenza): 1

• Add vancomycin or linezolid to the above regimens 1

Treatment Duration and Monitoring

Minimum treatment duration is 5 days, provided the patient: 1

• Has been afebrile for 48-72 hours
• Has no more than one sign of clinical instability (heart rate >100, respiratory rate >24, systolic BP <90mmHg, oxygen saturation <90%, inability to maintain oral intake, abnormal mental status) 1

Longer durations are needed if initial therapy was inactive against the identified pathogen or if complicated by extrapulmonary infection (meningitis, endocarditis). 1

Switch from IV to oral therapy when: 1

• Hemodynamically stable and clinically improving
• Able to ingest medications
• Normally functioning gastrointestinal tract 1

Patients can be discharged immediately after switching to oral therapy without prolonged observation. 1

Critical Management Considerations

For patients admitted through the emergency department, administer the first antibiotic dose while still in the ED to reduce mortality from delayed treatment. 1

Common pitfalls to avoid:

• Using macrolide monotherapy in areas with >25% pneumococcal macrolide resistance 1
• Prescribing fluoroquinolones as first-line for healthy outpatients without comorbidities (promotes resistance and has FDA warnings for serious adverse effects) 1
• Treating for MRSA or Pseudomonas without specific risk factors (leads to unnecessary broad-spectrum exposure) 1
• Continuing antibiotics beyond 5 days in clinically stable patients (promotes resistance and adverse effects) 1
• Delaying ICU admission in patients meeting severe CAP criteria (associated with higher mortality) 1

The 2019 guidelines eliminated "healthcare-associated pneumonia" as a treatment category, as this classification led to unnecessary broad-spectrum antibiotic use without improving outcomes. 2