What medications are used to treat cellulitis of the ear that is not otitis externa (swimmer's ear)?

Treatment of Cellulitis of the Left Ear (Not Swimmer's Ear)

For cellulitis of the ear that is NOT otitis externa (swimmer's ear), treat with oral beta-lactam antibiotics targeting streptococci and methicillin-sensitive Staphylococcus aureus, specifically cephalexin 500 mg four times daily or dicloxacin 250-500 mg every 6 hours for 5 days. 1

Understanding the Clinical Distinction

This is a critical diagnostic point: you are treating cellulitis of the external ear structures (pinna, periauricular skin), not acute otitis externa (AOE) of the ear canal. 2, 3

• AOE presents with ear canal inflammation, tragal tenderness, and is caused primarily by Pseudomonas aeruginosa (20-60%) and Staphylococcus aureus (10-70%), requiring topical antibiotic drops as definitive treatment. 2
• Cellulitis of the ear involves the skin and subcutaneous tissue of the external ear structures and follows the same treatment principles as cellulitis elsewhere on the body. 1, 4

First-Line Antibiotic Selection

Beta-lactam monotherapy is the standard of care with 96% success rates for typical uncomplicated cellulitis. 1

Recommended oral regimens:

• Cephalexin 500 mg orally four times daily 1, 5
• Dicloxacillin 250-500 mg orally every 6 hours 1
• Amoxicillin (alternative option) 1
• Penicillin V 250-500 mg orally four times daily (alternative) 1

Treatment duration:

• Treat for exactly 5 days if clinical improvement occurs; extend only if symptoms have not improved within this timeframe. 1
• Traditional 7-14 day courses are no longer necessary for uncomplicated cases. 1

When to Add MRSA Coverage

Do NOT routinely add MRSA coverage for typical nonpurulent ear cellulitis. MRSA is an uncommon cause of typical cellulitis even in high-prevalence settings. 1, 4

Add MRSA-active antibiotics ONLY when these specific risk factors are present: 1

• Penetrating trauma or insect bites to the ear
• Purulent drainage or exudate
• Injection drug use
• Known MRSA colonization or infection elsewhere
• Systemic inflammatory response syndrome (SIRS)
• Failure to respond to beta-lactam therapy after 48-72 hours

If MRSA coverage is needed: 1, 6

• Clindamycin 300-450 mg orally every 6 hours (covers both streptococci and MRSA, avoiding need for combination therapy)
• Trimethoprim-sulfamethoxazole (TMP-SMX) PLUS a beta-lactam (combination required because TMP-SMX lacks reliable streptococcal coverage) 1
• Doxycycline 100 mg orally twice daily PLUS a beta-lactam (combination required) 1

Special Considerations for Penicillin/Cephalosporin Allergy

For patients with beta-lactam allergy: 6

• Clindamycin 300-450 mg orally three times daily for 5-7 days (first-line choice, covers both streptococci and MRSA) 6
• Doxycycline 100 mg orally twice daily (alternative, provides MRSA coverage but requires combination with beta-lactam for typical cellulitis unless MRSA features present) 6
• Levofloxacin 500 mg daily (reserve for beta-lactam allergies, lacks reliable MRSA coverage) 1

Never use TMP-SMX in sulfa-allergic patients due to risk of severe reactions including Stevens-Johnson syndrome. 6

When to Hospitalize and Use IV Antibiotics

Indications for hospitalization: 1

• Systemic inflammatory response syndrome (fever >38°C, tachycardia >90 bpm, tachypnea >24 rpm)
• Hypotension or hemodynamic instability
• Altered mental status or confusion
• Severe immunocompromise or neutropenia
• Concern for necrotizing infection

IV antibiotic regimens for hospitalized patients: 1

• Cefazolin 1-2 g IV every 8 hours (preferred IV beta-lactam for uncomplicated cellulitis)
• Vancomycin 15-20 mg/kg IV every 8-12 hours (for MRSA coverage or severe infection)
• For severe cellulitis with systemic toxicity: Vancomycin 15-20 mg/kg IV every 8-12 hours PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours 1

Essential Adjunctive Measures

Beyond antibiotics, these interventions accelerate recovery: 1

• Elevation of the affected area promotes gravitational drainage of edema and inflammatory substances 1
• Adequate analgesia should be prescribed and documented, with pain typically improving within 48-72 hours 3
• Treat predisposing conditions including chronic edema, venous insufficiency, or underlying dermatitis 1

Critical Pitfalls to Avoid

• Do not use topical antibiotic ear drops for cellulitis of the external ear structures—these are indicated only for otitis externa (ear canal infection). 2, 3
• Do not reflexively add MRSA coverage simply because the patient is hospitalized or because community MRSA rates are high—beta-lactam monotherapy succeeds in 96% of typical cases. 1, 4
• Do not use doxycycline or TMP-SMX as monotherapy for typical cellulitis, as their activity against beta-hemolytic streptococci is unreliable. 1
• Reassess in 24-48 hours to verify clinical response—if spreading despite appropriate antibiotics, consider necrotizing infection, MRSA, or misdiagnosis. 1

Warning Signs Requiring Emergent Evaluation

Obtain emergent surgical consultation if any of these features develop: 1

• Severe pain out of proportion to examination
• Skin anesthesia or "wooden-hard" subcutaneous tissues
• Rapid progression despite antibiotics
• Bullous changes or skin necrosis
• Gas in tissue on imaging

These suggest necrotizing fasciitis requiring immediate surgical debridement and broad-spectrum IV antibiotics (vancomycin or linezolid PLUS piperacillin-tazobactam or a carbapenem). 1