Medication for Community-Acquired Pneumonia (CAP) and Acute Gastroenteritis (AGE)
Community-Acquired Pneumonia Treatment
Outpatient CAP Without Comorbidities
For healthy adults without comorbidities, amoxicillin 1 g three times daily is the first-line treatment for community-acquired pneumonia 1, 2, 3.
Amoxicillin demonstrates strong efficacy despite lacking coverage for atypical organisms, with a long safety track record and moderate quality evidence supporting its use 1, 3.
Doxycycline 100 mg twice daily is an acceptable alternative, though supported by lower quality evidence 1, 3.
Macrolide monotherapy (azithromycin 500 mg daily or clarithromycin 500 mg twice daily) should only be used in areas with pneumococcal macrolide resistance <25% 2, 3.
Outpatient CAP With Comorbidities
For adults with comorbidities, use either combination therapy with amoxicillin-clavulanate plus a macrolide OR monotherapy with a respiratory fluoroquinolone 1, 2, 3.
Combination therapy: Amoxicillin-clavulanate plus azithromycin 500 mg daily or clarithromycin 500 mg twice daily provides coverage for both typical and atypical pathogens 1, 2, 3.
Fluoroquinolone monotherapy: Levofloxacin 750 mg daily or moxifloxacin 400 mg daily offers broad-spectrum coverage with convenient once-daily dosing 1, 2.
Critical caveat: Patients with recent antibiotic exposure should receive treatment from a different antibiotic class to reduce resistance risk 1, 2.
Hospitalized Non-Severe CAP
For hospitalized patients without severe CAP, use a β-lactam (ampicillin-sulbactam, cefotaxime, ceftaroline, or ceftriaxone) plus a macrolide (azithromycin or clarithromycin) 1, 4.
β-lactam plus macrolide combination demonstrates strong evidence with moderate quality, showing mortality benefit in observational studies 1.
Alternative: β-lactam plus respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) is equally acceptable 1.
Minimum treatment duration is 3 days for responding patients, with typical courses of 5-7 days 4.
Hospitalized Severe CAP
For severe CAP, use a β-lactam plus a macrolide (strong recommendation) or a β-lactam plus a respiratory fluoroquinolone 1, 2.
Meta-analysis of nearly 10,000 critically ill patients showed macrolide-containing regimens reduced mortality by 18% relative risk (3% absolute risk) compared to non-macrolide therapies 1.
Systemic corticosteroids administered within 24 hours of severe CAP development may reduce 28-day mortality 4.
For pathogens like Legionella, Staphylococcus, or gram-negative enteric bacilli, extend treatment to 14-21 days 2.
Third-Line Option for Contraindications
For patients with contraindications to both macrolides and fluoroquinolones, use a β-lactam plus doxycycline 100 mg twice daily 1, 5.
- Doxycycline demonstrates comparable efficacy to levofloxacin in hospitalized CAP patients, with significantly lower cost ($64.98 vs $122.07) and shorter length of stay (4.0 vs 5.7 days) 5.
Special Considerations for CAP
Pathogen testing: All patients should be tested for COVID-19 and influenza when these viruses are circulating, as results may affect treatment decisions 4.
Resistance patterns: Only 38% of hospitalized CAP patients have an identified pathogen; Streptococcus pneumoniae accounts for approximately 15% of identified cases 4.
Fluoroquinolone warnings: Use fluoroquinolones judiciously due to FDA warnings regarding adverse events including tendon rupture, peripheral neuropathy, and CNS effects 1, 3.
Treatment failure: Reassess patients not improving within 48-72 hours and consider hospitalization for outpatients or escalation for inpatients 3.
Acute Gastroenteritis (AGE) Treatment
No evidence was provided regarding acute gastroenteritis treatment in the supplied studies. The evidence exclusively addresses community-acquired pneumonia management. For AGE recommendations, additional guidelines focusing on gastroenteritis would be required.
Common Pitfalls to Avoid
Do not use macrolide monotherapy in areas with high pneumococcal resistance (≥25%) 2, 3.
Do not underestimate severity: Failure to recognize severe CAP leads to inadequate treatment intensity and worse outcomes 2.
Do not ignore recent antibiotic exposure: This significantly increases resistance risk and requires switching to a different antibiotic class 1, 2.
Do not use oral cephalosporins like cefdinir for severe CAP requiring hospitalization; parenteral β-lactams are required 6.