What is the recommended antibiotic treatment for a child with cellulitis of a skin wound, considering potential penicillin allergy and varying severity of infection?

Antibiotic Treatment for Pediatric Cellulitis of Skin Wounds

First-Line Antibiotic Selection

For children with uncomplicated cellulitis of a skin wound, beta-lactam monotherapy with cephalexin or dicloxacillin is the standard of care, successful in 96% of cases, and MRSA coverage should NOT be added routinely. 1, 2

Standard Oral Regimens

• Cephalexin 25-50 mg/kg/day divided into 3-4 doses (maximum 500 mg per dose) provides excellent coverage against streptococci and methicillin-sensitive Staphylococcus aureus 1, 2, 3
• Dicloxacillin 12.5-25 mg/kg/day divided every 6 hours is equally effective as first-line therapy 3, 4
• Amoxicillin-clavulanate 45 mg/kg/day (amoxicillin component) divided twice daily is recommended by French pediatric infectious disease experts as first-line for severe skin infections requiring antibiotics 4

Treatment Duration

Treat for exactly 5 days if clinical improvement occurs; extend only if symptoms have not improved within this timeframe. 1, 2 There is no evidence that 10-day courses are superior to 5-7 day courses for uncomplicated cellulitis 2, 3

When to Add MRSA Coverage

MRSA coverage should be added ONLY when specific risk factors are present 1, 2:

• Penetrating trauma or injection drug use 1, 2
• Purulent drainage or exudate (in absence of drainable abscess) 1, 2
• Evidence of MRSA infection elsewhere or known nasal colonization 1, 2
• Systemic inflammatory response syndrome (SIRS) with fever, tachycardia, or altered mental status 1, 2
• Failure to respond to beta-lactam therapy after 48-72 hours 1, 2

MRSA-Active Oral Regimens for Children

When MRSA coverage is indicated:

• Clindamycin 10-13 mg/kg/dose every 6-8 hours (maximum 450 mg per dose) provides single-agent coverage for both streptococci and MRSA, but use ONLY if local clindamycin resistance rates are <10% 1, 5
• Trimethoprim-sulfamethoxazole 4-6 mg/kg/dose (TMP component) twice daily PLUS a beta-lactam (cephalexin or amoxicillin) for dual coverage 1, 2
• Doxycycline 2 mg/kg/dose twice daily (maximum 100 mg per dose) PLUS a beta-lactam for children >8 years and <45 kg 1, 2

Critical caveat: Never use TMP-SMX or doxycycline as monotherapy for typical cellulitis, as their activity against beta-hemolytic streptococci is unreliable 1, 2

Penicillin Allergy Considerations

For children with documented penicillin allergy:

• Clindamycin 10-13 mg/kg/dose every 6-8 hours is the preferred alternative, providing coverage for both streptococci (99.5% of S. pyogenes remain susceptible) and MRSA if local resistance is low 1, 2, 5
• Cross-reactivity between penicillins and cephalosporins is only 2-4%, so cephalexin may still be used in non-immediate hypersensitivity reactions 2

Hospitalization and IV Therapy

Hospitalize children with cellulitis who have 1, 2:

• Age <6 months with moderate-to-severe disease 2
• SIRS criteria (fever >38°C, tachycardia, tachypnea) 1, 2
• Hypotension or altered mental status 1, 2
• Severe immunocompromise or neutropenia 1, 2
• Concern for deeper or necrotizing infection 1, 2

IV Antibiotic Regimens for Hospitalized Children

• Vancomycin 15 mg/kg IV every 6 hours is first-line for complicated cellulitis requiring hospitalization (A-II evidence) 1, 2
• Clindamycin 10-13 mg/kg/dose IV every 6-8 hours (to deliver 40 mg/kg/day) is appropriate for stable children without ongoing bacteremia if local clindamycin resistance is <10%, with transition to oral therapy if strain is susceptible (A-II evidence) 1, 2
• Linezolid 10 mg/kg/dose IV every 8 hours for children <12 years or 600 mg IV twice daily for children ≥12 years is an alternative (A-II evidence) 1, 2

For severe cellulitis with systemic toxicity or suspected necrotizing fasciitis: Use vancomycin 15-20 mg/kg IV every 8-12 hours PLUS piperacillin-tazobactam 3.375 g IV every 6 hours (or age-appropriate dosing), treating for 7-14 days based on clinical response 1, 2

Special Considerations for Minor Infections

For children with minor skin infections such as impetigo and secondarily infected lesions (eczema, ulcers, lacerations), mupirocin 2% topical ointment can be used (A-III evidence) 1

Critical Pitfalls to Avoid

• Never use tetracyclines (doxycycline, minocycline) in children <8 years of age due to tooth discoloration and bone growth effects (A-II evidence) 1, 2
• Do not routinely add MRSA coverage for typical nonpurulent cellulitis without specific risk factors, as this represents overtreatment and increases antibiotic resistance 1, 2
• Do not use rifampin as single agent or adjunctive therapy for skin and soft tissue infections (A-III evidence) 1
• Always assess for abscess with ultrasound if clinically uncertain, as purulent collections require incision and drainage as primary treatment, with antibiotics playing only a subsidiary role 2, 6

Essential Adjunctive Measures

• Elevate the affected extremity above heart level to promote gravity drainage of edema and inflammatory substances 1, 2
• Examine interdigital toe spaces for tinea pedis, fissuring, or maceration, and treat these to eradicate colonization and reduce recurrence 1, 2
• Keep draining wounds covered with clean, dry bandages and maintain good hand hygiene 1
• Avoid reusing or sharing personal items (razors, linens, towels) that have contacted infected skin 1