What is the treatment plan for a skin infection?

Treatment Plan for Skin Infections

For skin infections, the primary treatment approach is antimicrobial therapy with cephalexin 500 mg orally four times daily for 5-7 days for uncomplicated cases, while purulent infections require drainage as the primary intervention with antibiotics as adjunctive therapy. 1

Classification and Initial Assessment

The treatment plan depends on the type of skin infection:

1. Non-purulent infections (cellulitis/erysipelas)

   • Rapidly spreading areas of erythema, swelling, tenderness, and warmth
   • May have lymphangitis and regional lymph node inflammation
   • Systemic symptoms may include fever, tachycardia, confusion

2. Purulent infections (abscesses, furuncles, carbuncles)

   • Characterized by collections of pus
   • Primary treatment is drainage
   • Antibiotics may be adjunctive

Diagnostic Approach

• Cultures are unnecessary for typical cellulitis cases 2
• Blood cultures should be obtained for patients with:
  • Malignancy
  • Severe systemic features (high fever, hypotension)
  • Unusual predisposing factors (immersion injury, animal bites)
  • Immunocompromised status 2

Treatment Algorithm

1. Non-purulent Infections (Cellulitis/Erysipelas)

First-line therapy:

• Cephalexin 500 mg orally four times daily for 5-7 days 2, 1, 3
• Alternative: Dicloxacillin 500 mg orally four times daily 1

For penicillin-allergic patients:

• Clindamycin 300-450 mg orally three times daily 1

For severe infections requiring IV therapy:

• Cefazolin, oxacillin, or nafcillin 2, 1

2. Purulent Infections (Abscesses)

• Primary treatment: Incision and drainage 2
• Adjunctive antibiotics indicated if:
  • Systemic response present
  • Erythema/induration extending >5 cm from wound edge
  • Fever or other systemic symptoms 2

Antibiotic options after drainage:

• MSSA coverage: Cephalexin 500 mg four times daily 1, 3
• MRSA consideration: Add trimethoprim-sulfamethoxazole or doxycycline 2

3. Special Situations

Necrotizing infections:

• Prompt surgical consultation is essential 2
• Broad empiric coverage: Vancomycin or linezolid plus piperacillin-tazobactam or a carbapenem 2
• For confirmed Group A streptococcal infection: Penicillin plus clindamycin 2

Pyomyositis:

• Early drainage of purulent material 2
• Initial empiric therapy with vancomycin 2
• For confirmed MSSA: Cefazolin or antistaphylococcal penicillin 2

Duration of Therapy

• Uncomplicated skin infections: 5-7 days 2, 1
• More severe infections: 7-14 days 1
• Pyomyositis: 2-3 weeks of therapy 2

Monitoring and Follow-up

• Reassess within 48-72 hours to evaluate response 1
• Consider hospitalization if:
  • No improvement within 24-48 hours of outpatient treatment
  • Concern for deeper or necrotizing infection
  • Poor adherence anticipated
  • Immunocompromised patient 1

Practical Considerations

• Twice-daily dosing of cephalexin has been shown to be as effective as four-times-daily dosing, which may improve compliance 4
• Cephalexin is well-absorbed orally and has high bioavailability 5
• For pediatric patients, the usual recommended daily dosage is 25-50 mg/kg in divided doses 3
• In severe infections, the pediatric dosage may be doubled 3

Prevention of Recurrence

• Identify and treat predisposing conditions (edema, obesity, eczema, venous insufficiency) 1
• Consider prophylactic antibiotics for patients with 3-4 episodes per year 1

Cautions

• Up to 10% of penicillin-allergic patients may also be allergic to cephalosporins 1
• Dose adjustment required for patients with creatinine clearance less than 30 ml/min 1, 3
• MRSA is an unusual cause of typical cellulitis, and specific coverage is usually unnecessary unless there are risk factors 2