What antibiotics are appropriate for a patient with an ear infection?

Antibiotic Options for Ear Infections

For acute otitis media (middle ear infection), prescribe high-dose amoxicillin 80-90 mg/kg/day divided twice daily as first-line therapy; for otitis externa (outer ear canal infection), use topical fluoroquinolone ear drops such as ofloxacin or ciprofloxacin. 1

Acute Otitis Media (Middle Ear Infection)

First-Line Antibiotic

• Amoxicillin 80-90 mg/kg/day divided into 2 doses is the preferred initial treatment for most patients with acute otitis media 1
• This high-dose regimen achieves 92% eradication of Streptococcus pneumoniae (including penicillin-resistant strains), 84% eradication of beta-lactamase-negative Haemophilus influenzae, and 62% eradication of beta-lactamase-positive H. influenzae 2
• Maximum adult dose is 2 grams per dose 1
• Treatment duration: 10 days for children under 2 years; 7 days for children 2-5 years with mild-moderate disease; 5-7 days for children ≥6 years and adults with uncomplicated cases 1, 2

When to Use Amoxicillin-Clavulanate Instead

Switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component + 6.4 mg/kg/day clavulanate in 2 divided doses) when: 1

• Patient received amoxicillin within the past 30 days 1
• Concurrent purulent conjunctivitis is present (suggests H. influenzae) 3, 1
• Patient attends daycare or lives in area with high prevalence of beta-lactamase-producing organisms 1
• Initial amoxicillin therapy failed 1

Penicillin-Allergic Patients (Non-Severe Allergy)

For patients with non-IgE-mediated penicillin allergy, use second- or third-generation cephalosporins (cross-reactivity is only ~0.1%): 1

• Cefdinir 14 mg/kg/day once daily (preferred for convenience) 1
• Cefuroxime 30 mg/kg/day divided twice daily 1
• Cefpodoxime 10 mg/kg/day divided twice daily 1

True Type I Penicillin Allergy (Anaphylaxis)

• Avoid all beta-lactams including cephalosporins 2
• Use macrolides (azithromycin or clarithromycin) as last resort, though bacterial failure rates are 20-25% due to pneumococcal resistance 1, 2
• Do not use trimethoprim-sulfamethoxazole if sulfa allergy exists 2

Treatment Failure Management

Reassess at 48-72 hours if symptoms worsen or fail to improve: 1

1. If initially observed without antibiotics → start high-dose amoxicillin 1
2. If amoxicillin failed → switch to amoxicillin-clavulanate 1
3. If amoxicillin-clavulanate failed → give intramuscular ceftriaxone 50 mg/kg once daily for 3 consecutive days (3-day course superior to single dose) 1, 2

Critical pitfall: Do not use trimethoprim-sulfamethoxazole or erythromycin-sulfisoxazole for treatment failures due to substantial resistance 1

Otitis Externa (Outer Ear Canal Infection / "Swimmer's Ear")

First-Line Treatment

Use topical fluoroquinolone ear drops—these are superior to oral antibiotics: 3

• Ofloxacin 0.3% otic solution: 10 drops in affected ear once daily for 7 days (ages ≥6 months) 4
• Ciprofloxacin 0.2% otic solution: 0.25 mL (entire single-dose container) twice daily for 7 days 5
• Ciprofloxacin-dexamethasone combination drops also effective 3

Why Topical Antibiotics Are Preferred

• Clinical cure rates of 77-96% with topical therapy vs. only 30-67% with oral antibiotics 3
• Higher drug concentration at infection site 3
• Better coverage of Pseudomonas aeruginosa and Staphylococcus aureus (the predominant pathogens in otitis externa) 3, 5

Administration Technique

• Warm the bottle by holding in hands for 1-2 minutes to minimize dizziness 5
• Patient lies with affected ear upward 5, 4
• Instill drops and maintain position for at least 1 minute (up to 5 minutes) 5, 4
• For ear canal infections, gently pull outer ear upward and backward to allow drops to flow down 4

Tympanostomy Tubes with Acute Otorrhea

For children with ear tubes who develop drainage from the ear canal:

• Topical antibiotic ear drops alone (ofloxacin or ciprofloxacin-dexamethasone) are the best treatment 3
• Place drops in ear canal twice daily for up to 10 days 3
• "Pump" the tragus (flap of skin in front of ear canal) after placing drops to help them enter the tube 3
• Oral antibiotics are unnecessary unless the child is very ill or has another indication 3

Common Pitfalls to Avoid

• Never use ototoxic preparations (aminoglycosides) when tympanic membrane integrity is uncertain 1
• Do not prescribe antibiotics for isolated tympanic membrane redness without middle ear effusion 1
• Avoid topical antibiotics for middle ear infections without tubes—they cannot penetrate intact tympanic membrane 3
• Do not use azithromycin as first-line for acute otitis media—pneumococcal resistance exceeds 40% with bacterial failure rates of 20-25% 2
• Antibiotics do not prevent complications—33-81% of children who develop mastoiditis had received prior antibiotics 1

Pain Management (Essential for All Ear Infections)

• Immediately initiate acetaminophen or ibuprofen for all patients with ear pain, regardless of antibiotic decision 1
• Analgesics provide relief within 24 hours, whereas antibiotics provide no symptomatic benefit in the first 24 hours 1
• Continue pain medication throughout the acute phase 1