What is the first-line antibiotic (abx) for ear infections?

First-Line Antibiotics for Ear Infections

Amoxicillin is the recommended first-line antibiotic treatment for acute otitis media (ear infections) in most patients due to its effectiveness against common bacterial pathogens, safety profile, low cost, acceptable taste, and narrow microbiologic spectrum. 1

Age-Based Treatment Approach

Children Under 2 Years

• Antibiotic therapy is recommended for all cases of acute otitis media (AOM) (Grade A evidence) 1
• First-line treatment: High-dose amoxicillin (80-90 mg/kg per day in 2 divided doses) 1

Children Over 2 Years

• Antibiotic therapy is only recommended for cases with marked symptoms (high fever, intense earache) 1
• Observation with symptomatic therapy is reasonable for mild cases, with reassessment after 48-72 hours 1
• When antibiotics are indicated, use high-dose amoxicillin as first-line therapy 1

Adults

• AOM is rare in adults, but when present, the bacteria involved are the same as in children, and treatment choices are similar 1
• Amoxicillin remains the first-line agent 1

Special Circumstances Requiring Alternative First-Line Therapy

High-dose amoxicillin-clavulanate should be used as first-line therapy instead of amoxicillin alone in patients with:

• Amoxicillin use within the previous 30 days 1
• Concurrent conjunctivitis (suggests H. influenzae infection) 1
• Need for coverage of β-lactamase-producing organisms 1

Alternative Treatments for Penicillin Allergy

For patients with penicillin allergy, recommended alternatives include:

• Cefdinir (14 mg/kg per day in 1 or 2 doses)
• Cefuroxime (30 mg/kg per day in 2 divided doses)
• Cefpodoxime (10 mg/kg per day in 2 divided doses) 1

Note: Cross-reactivity between penicillins and second/third-generation cephalosporins is now known to be negligible, making these safe options for most patients with non-severe penicillin allergy 1

Treatment Failures

If initial treatment fails after 48-72 hours:

1. Switch to amoxicillin-clavulanate if amoxicillin was used initially
2. Consider ceftriaxone for 3 days if further treatment failure occurs 1

Important Clinical Considerations

• Proper diagnosis is crucial: Ensure visualization of the tympanic membrane to confirm AOM versus otitis media with effusion (OME) 1
• Duration of therapy:
  • 8-10 days for children under 2 years
  • 5 days for older children and adults 1
• Isolated redness of the tympanic membrane with normal landmarks is not an indication for antibiotic therapy 1
• Otitis media with effusion (fluid without acute inflammation) does not require antibiotics unless it persists beyond 3 months 1

Bacterial Resistance Considerations

The choice of amoxicillin addresses the most common pathogens in AOM:

• S. pneumoniae (high-dose amoxicillin overcomes intermediate resistance)
• H. influenzae (non-β-lactamase-producing strains)
• M. catarrhalis (though intrinsically resistant to amoxicillin, clinical outcomes are generally good) 1

For suspected β-lactamase-producing organisms, amoxicillin-clavulanate provides appropriate coverage 1, 2

Common Pitfalls to Avoid

1. Treating isolated redness of the tympanic membrane without other signs of AOM
2. Prescribing antibiotics without adequate visualization of the tympanic membrane
3. Using broad-spectrum antibiotics as first-line when amoxicillin would be sufficient
4. Failing to distinguish between AOM (requires antibiotics in young children) and OME (generally doesn't require antibiotics)
5. Not considering recent antibiotic use when selecting therapy

Amoxicillin has stood the test of time as an effective "old friend" for the treatment of ear infections, despite the emergence of some resistant organisms 2.