What oral antibiotics are recommended for treating common bacterial infections like pneumonia?

Recommended Oral Antibiotics for Common Bacterial Pneumonia

For treating common bacterial pneumonia, amoxicillin is the preferred first-line oral antibiotic therapy for both adults and children, with macrolides recommended for atypical pathogens. 1, 2

First-Line Therapy Options

Adults with Community-Acquired Pneumonia (CAP):

• First choice: Amoxicillin 1g three times daily (3g/day) 2
• Duration: 5-7 days for uncomplicated cases 1, 3

Children with Community-Acquired Pneumonia:

• First choice: Amoxicillin 75-100 mg/kg/day divided in 3 doses 1
• Duration: 5-7 days for responding patients 1, 3

Pathogen-Specific Recommendations

Streptococcus pneumoniae:

• Amoxicillin (preferred oral β-lactam) 2
• Covers >93% of S. pneumoniae strains, including many resistant strains

Atypical Pathogens (Mycoplasma, Chlamydophila):

• First choice: Azithromycin 500mg on day 1, then 250mg daily for 4 days 1, 4
• Alternative: Clarithromycin 500mg twice daily 1
• For children: Azithromycin 10mg/kg on day 1, then 5mg/kg daily for days 2-5 1

Haemophilus influenzae:

• If β-lactamase negative: Amoxicillin 75-100mg/kg/day in 3 doses
• If β-lactamase producing: Amoxicillin-clavulanate (amoxicillin component 45mg/kg/day in 3 doses or 90mg/kg/day in 2 doses) 1

Alternative Therapies for Penicillin Allergy

• Macrolides: Azithromycin or clarithromycin 1, 4
• Respiratory fluoroquinolones: Levofloxacin 500mg once daily or moxifloxacin 400mg once daily 1
  • Note: Fluoroquinolones should be used judiciously due to resistance concerns and are not recommended as first-line agents 1
• Doxycycline: 100mg twice daily (for patients >7 years old) 1

Special Considerations

Severe CAP requiring hospitalization:

• Consider parenteral therapy initially with transition to oral therapy when clinically stable 1
• Combined therapy with a β-lactam plus macrolide is recommended 1

Risk factors for drug-resistant pathogens:

• Recent antibiotic use (within 3 months)
• Age >65 years
• Comorbidities (COPD, diabetes, renal disease)
• Immunosuppression

Clinical Pearls and Pitfalls

1. Important pitfall: Azithromycin should not be used as monotherapy in areas with high pneumococcal resistance 4

2. Duration considerations: Limit antibiotic exposure to the shortest effective duration (typically 5-7 days for uncomplicated cases) to minimize resistance development 1

3. Treatment response: Assess response within 48-72 hours of initiating therapy. If no improvement, consider alternative diagnosis or resistant pathogen 2

4. Common error: Using trimethoprim-sulfamethoxazole for CAP is not recommended due to inadequate activity against penicillin-resistant S. pneumoniae 2

5. Follow-up: Arrange clinical review at around 6 weeks for all patients, with chest radiograph for those with persistent symptoms or at higher risk of underlying malignancy 1

The evidence strongly supports short-course therapy (5-7 days) for uncomplicated pneumonia, which is as effective as longer courses while reducing antibiotic exposure 3. Studies have demonstrated equivalent clinical success rates between short-course azithromycin (3-5 days) and longer courses of amoxicillin-based regimens (7-10 days) 5, 6.