What antibiotic regimen is recommended for the treatment of head cellulitis?

Antibiotic Treatment for Head Cellulitis

For head cellulitis, use a first-generation cephalosporin (cephalexin 500 mg every 6 hours) or a penicillinase-resistant penicillin (dicloxacillin 250-500 mg every 6 hours) for 5 days if clinical improvement occurs. 1, 2

First-Line Antibiotic Selection

Beta-lactam monotherapy is the standard of care for typical head cellulitis, with a 96% success rate. 1 The causative organisms are predominantly β-hemolytic Streptococcus and methicillin-sensitive Staphylococcus aureus, making MRSA coverage unnecessary in most cases. 1, 3

Recommended Oral Regimens:

• Cephalexin 500 mg every 6 hours (preferred first-line agent) 1, 2
• Dicloxacillin 250-500 mg every 6 hours 1, 2
• Amoxicillin-clavulanate 875/125 mg twice daily (provides broader coverage including beta-lactamase producers) 1, 2
• Penicillin V 250-500 mg four times daily 1

For Hospitalized Patients Requiring IV Therapy:

• Cefazolin 1-2 g IV every 8 hours (preferred IV agent) 1, 2
• Oxacillin 2 g IV every 6 hours (alternative) 1

Treatment Duration

Treat for exactly 5 days if clinical improvement is evident; extend only if symptoms have not improved within this timeframe. 1, 2 This shorter duration is as effective as traditional 10-day courses for uncomplicated cellulitis. 1, 4 The landmark levofloxacin study demonstrated 98% clinical resolution at 14 days with 5-day therapy versus 98% with 10-day therapy. 1, 4

When to Add MRSA Coverage

MRSA is an uncommon cause of typical head cellulitis and routine coverage is unnecessary. 1, 2 However, add MRSA-active antibiotics when these specific risk factors are present:

• Penetrating trauma or injection drug use 1, 2
• Purulent drainage or exudate visible 1, 2
• Evidence of MRSA infection elsewhere or known nasal colonization 1, 2
• Systemic inflammatory response syndrome (SIRS): fever >38°C, tachycardia >90 bpm, tachypnea >24 rpm 1, 2
• Failure to respond to beta-lactam therapy after 48-72 hours 1, 5

MRSA Coverage Options:

• Clindamycin 300-450 mg every 6 hours (covers both streptococci and MRSA as monotherapy, use only if local resistance <10%) 1, 2
• Trimethoprim-sulfamethoxazole 1-2 DS tablets twice daily PLUS a beta-lactam (never use TMP-SMX alone due to inadequate streptococcal coverage) 1, 2
• Doxycycline 100 mg twice daily PLUS a beta-lactam (never use doxycycline alone) 1, 2

In MRSA-prevalent areas, antibiotics without MRSA activity have 4.22 times higher odds of treatment failure (95% CI 2.25-7.92). 5

Severe Infections Requiring Hospitalization

Hospitalize immediately if any of these criteria are present: 1, 2

• SIRS criteria (fever, tachycardia, hypotension)
• Altered mental status or confusion
• Hemodynamic instability
• Severe immunocompromise or neutropenia
• Concern for necrotizing fasciitis (severe pain out of proportion, skin anesthesia, rapid progression, gas in tissue, bullous changes)

For Severe Cellulitis with Systemic Toxicity:

Use mandatory broad-spectrum combination therapy: 1, 2

• Vancomycin 15-20 mg/kg IV every 8-12 hours PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours 1, 2
• Alternative: Linezolid 600 mg IV twice daily PLUS piperacillin-tazobactam 1
• Alternative: Vancomycin PLUS a carbapenem (meropenem 1 g IV every 8 hours) 1

Treat severe infections for 7-14 days, guided by clinical response. 1

Special Considerations for Head/Ear Cellulitis

Facial and ear cellulitis are predominantly caused by Streptococcus pyogenes (Group A Strep), making beta-lactam monotherapy highly effective. 2 The same first-line agents apply, with 99.5% of S. pyogenes strains remaining susceptible to clindamycin if penicillin allergy exists. 2

Essential Adjunctive Measures

• Elevate the affected area to promote gravity drainage of edema and inflammatory substances 1, 2
• Treat predisposing conditions: tinea pedis, trauma, venous eczema, lymphedema 1, 2
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adults to potentially hasten resolution, though evidence is limited 1, 2

Critical Pitfalls to Avoid

• Do not routinely add MRSA coverage for typical head cellulitis without specific risk factors—this represents overtreatment and increases resistance 1, 2
• Do not use doxycycline or TMP-SMX as monotherapy—their activity against beta-hemolytic streptococci is unreliable 1, 2
• Do not automatically extend treatment beyond 5 days—only extend if clinical improvement has not occurred 1, 2
• Do not delay surgical consultation if any signs of necrotizing infection are present (severe pain, rapid progression, systemic toxicity) 1
• Reassess within 24-48 hours to verify clinical response; treatment failure should prompt consideration of resistant organisms, abscess requiring drainage, or cellulitis mimickers 1, 2

Penicillin Allergy Considerations

For patients with penicillin allergy: 1, 2

• Clindamycin 300-450 mg every 6 hours (provides both streptococcal and MRSA coverage) 1, 2
• Levofloxacin 500 mg daily (reserve for true beta-lactam allergies) 1