What is the treatment for scalp cellulitis?

Treatment for Scalp Cellulitis

For typical scalp cellulitis, treatment should consist of an antimicrobial agent active against streptococci, such as penicillin, amoxicillin, cephalexin, or clindamycin for 5 days, with extension of therapy if improvement is not seen within this period. 1

Antimicrobial Selection Algorithm

Mild Cellulitis (No Systemic Signs)

• First-line therapy: Antimicrobial agent active against streptococci 1
  • Oral options:
    • Penicillin VK 250-500 mg every 6 hours
    • Amoxicillin 500 mg three times daily
    • Cephalexin 500 mg four times daily
    • Clindamycin 300-450 mg three times daily (for penicillin-allergic patients)

Moderate Cellulitis (With Systemic Signs)

• First-line therapy: Antimicrobial coverage for streptococci and possibly MSSA 1
  • Oral options:
    • Dicloxacillin 500 mg four times daily
    • Cephalexin 500 mg four times daily
    • Clindamycin 300-450 mg three times daily (penicillin-allergic patients)
  • IV options (if oral therapy not appropriate):
    • Cefazolin 1 g every 8 hours
    • Nafcillin/oxacillin 1-2 g every 4-6 hours

Severe Cellulitis or High Risk for MRSA

• When to suspect MRSA: Cellulitis associated with penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, injection drug use, or SIRS 1
• Treatment options:
  • Vancomycin 15 mg/kg every 12 hours IV
  • Linezolid 600 mg twice daily (oral or IV)
  • Daptomycin 4 mg/kg daily IV
  • Clindamycin 600 mg three times daily (if susceptible)
  • Combination therapy: SMX-TMP or doxycycline plus β-lactam (for outpatient treatment)

Duration of Therapy

• Standard duration: 5 days 1
• Extended therapy: Continue if infection has not improved within 5 days 1

Adjunctive Measures

• Elevation of the affected area to promote gravity drainage of edema 1
• Treatment of predisposing factors (e.g., scalp dermatitis, trauma sites) 1
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic patients to reduce inflammation 1

Special Considerations for Scalp Cellulitis

Dissecting Cellulitis of the Scalp

For severe, recalcitrant dissecting cellulitis of the scalp (a specific variant):

• Initial treatment with antibiotics active against S. aureus 2, 3
• For refractory cases:
  • Isotretinoin 3
  • Biologic agents like adalimumab or infliximab for severe cases 4, 3, 5
  • Surgical excision of affected areas with skin grafting for intractable disease 6

Hospitalization Criteria

Hospitalization should be considered if:

• Signs of systemic toxicity or SIRS are present
• Altered mental status
• Hemodynamic instability
• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Severely immunocompromised patient
• Outpatient treatment is failing 1

Diagnostic Considerations

• Routine cultures of blood or cutaneous aspirates are not recommended for typical cases 1
• Blood cultures should be obtained in patients with:
  • Malignancy on chemotherapy
  • Neutropenia
  • Severe cell-mediated immunodeficiency
  • Immersion injuries
  • Animal bites 1

Prevention of Recurrence

For patients with recurrent episodes:

• Identify and treat predisposing conditions (edema, scalp dermatitis) 1
• Consider prophylactic antibiotics for patients with 3-4 episodes per year:
  • Oral penicillin or erythromycin twice daily for 4-52 weeks
  • Intramuscular benzathine penicillin every 2-4 weeks 1

Remember that while MRSA is an uncommon cause of typical cellulitis, coverage should be considered in high-risk situations. The standard 5-day course is often sufficient, but be prepared to extend therapy if clinical improvement is not observed.