What is the first‑line antibiotic regimen (including dose and duration) for acute bacterial otitis media in a previously healthy child or adult, and what are the recommended treatments for otitis externa?

Best Antibiotics for Ear Infection

Acute Otitis Media (Middle Ear Infection)

High-dose amoxicillin at 80-90 mg/kg/day divided twice daily for children (or 500-875 mg twice daily for adults) is the first-line antibiotic for acute otitis media, with treatment duration of 10 days for children under 2 years and 5-7 days for older children and adults. 1, 2

First-Line Treatment Selection

• Amoxicillin is recommended as first-line therapy because it is effective against susceptible and intermediate-resistant Streptococcus pneumoniae, safe, inexpensive, has acceptable taste, and has a narrow microbiologic spectrum. 1, 2

• The high dose (80-90 mg/kg/day) is specifically needed to overcome intermediate and highly resistant pneumococcal strains, achieving 92% eradication of S. pneumoniae including penicillin-nonsusceptible strains. 3

• For adults, the standard dose is 500 mg every 12 hours for mild infections or 875 mg every 12 hours for more severe respiratory tract infections. 4

When to Use Amoxicillin-Clavulanate Instead

Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component for children; 875 mg/125 mg twice daily or 2000 mg/125 mg twice daily for adults) as first-line therapy if: 1, 3, 2

• The patient received amoxicillin in the previous 30 days
• Concurrent purulent conjunctivitis is present
• Recurrent AOM unresponsive to amoxicillin
• Adults with moderate-to-severe symptoms, age >65 years, comorbid conditions, or immunocompromised status

This combination provides coverage against beta-lactamase-producing Haemophilus influenzae (17-34% produce beta-lactamase) and Moraxella catarrhalis (100% produce beta-lactamase), which are the primary causes of treatment failure. 3

Treatment Duration

• Children under 2 years: 10 days 2, 4
• Children ≥2 years with mild-to-moderate disease: 5-7 days 2
• Adults with uncomplicated AOM: 5-7 days 3

The shorter duration for older children and adults is supported by different immune responses and lower risk of treatment failure. 3

Penicillin Allergy Alternatives

For non-Type I penicillin allergy (e.g., rash without anaphylaxis): 1, 2

• Cefdinir (14 mg/kg/day in 1-2 divided doses for children; standard adult dosing) - preferred due to highest patient acceptance 3
• Cefuroxime axetil (30 mg/kg/day in 2 divided doses for children; 500 mg twice daily for adults) 3
• Cefpodoxime (10 mg/kg/day in 2 divided doses) 3

For true Type I hypersensitivity (anaphylaxis) to beta-lactams: 3, 2

• Azithromycin or clarithromycin may be used, though bacterial failure rates of 20-25% are expected due to pneumococcal resistance exceeding 40% 3
• All cephalosporins must be avoided in documented Type I reactions 3

Management of Treatment Failure

If symptoms worsen or fail to improve within 48-72 hours: 1, 3, 2

1. Reassess to confirm AOM diagnosis and exclude other causes
2. If initially managed with observation, begin antibacterial therapy
3. If initially treated with amoxicillin, switch to amoxicillin-clavulanate (90 mg/kg/day)
4. If initially treated with amoxicillin-clavulanate, consider ceftriaxone 50 mg/kg IM/IV (maximum 1-2 grams) for 1-3 days 3, 2

Ceftriaxone provides excellent coverage against resistant S. pneumoniae, beta-lactamase-producing H. influenzae, and M. catarrhalis. 3

Pain Management

Pain should be addressed immediately with oral analgesics (acetaminophen or ibuprofen) regardless of antibiotic decision. 1, 3 This is a strong recommendation as many cases of AOM involve significant pain, especially during the first 24 hours. 1

Observation Option (Watchful Waiting)

Observation without antibiotics for 48-72 hours is appropriate for: 1, 2

• Children 6 months to 2 years with non-severe illness and uncertain diagnosis
• Children ≥2 years without severe symptoms or with uncertain diagnosis
• This option is NOT established for adults with AOM 3

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Otitis Externa (Outer Ear Canal Infection)

Ciprofloxacin 0.2% otic solution (0.25 mL per dose) instilled into the affected ear twice daily for 7 days is FDA-approved for acute otitis externa caused by Pseudomonas aeruginosa or Staphylococcus aureus. 5

• This is a topical treatment for outer ear canal infections, not middle ear infections
• The solution should be instilled approximately 12 hours apart 5
• Discontinue at the first appearance of skin rash or hypersensitivity 5

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Critical Pitfalls to Avoid

• Do not diagnose AOM based solely on isolated redness of the tympanic membrane with normal landmarks - this does not warrant antibiotic therapy 3, 2

• Do not confuse otitis media with effusion (OME) for acute otitis media - middle ear fluid without acute inflammation does not require antibiotics 3

• Avoid fluoroquinolones as first-line therapy due to antimicrobial resistance concerns and side effects 3

• Do not use macrolides (azithromycin) or trimethoprim-sulfamethoxazole as first-line therapy due to resistance rates exceeding 40% for macrolides and 50% for TMP-SMX against S. pneumoniae 3

• Do not substitute two 250 mg/125 mg amoxicillin-clavulanate tablets for one 500 mg/125 mg tablet - they contain the same amount of clavulanic acid (125 mg) and are not equivalent 4

• NSAIDs at anti-inflammatory doses and corticosteroids have not demonstrated efficacy for AOM treatment and should not be relied upon as primary therapy 3