Antibiotic Treatment for Pediatric Cellulitis
For uncomplicated, non-purulent cellulitis in children, first-line therapy is oral beta-lactam monotherapy with cephalexin 25–50 mg/kg/day divided every 6 hours for 5 days, which achieves 96% clinical success without requiring MRSA coverage. 1, 2
First-Line Oral Therapy for Uncomplicated Cellulitis
Beta-lactam antibiotics targeting streptococci and methicillin-sensitive Staphylococcus aureus are the standard of care:
- Cephalexin 25–50 mg/kg/day divided every 6 hours (maximum 500 mg per dose) provides excellent coverage against beta-hemolytic streptococci and MSSA, the primary pathogens in typical pediatric cellulitis 1, 2, 3
- Dicloxacillin 12.5–25 mg/kg/day divided every 6 hours is an equally effective alternative 1
- Amoxicillin 40–50 mg/kg/day divided every 8 hours is appropriate for streptococcal coverage 1, 2
- Treatment duration is 5 days if clinical improvement occurs; extend only if warmth, tenderness, or erythema have not improved within this timeframe 1
When to Add MRSA Coverage
MRSA-active antibiotics should be added ONLY when specific high-risk features are present:
- Purulent drainage or exudate visible at the infection site 4, 5
- Penetrating trauma or injection drug use (rare in children but relevant in adolescents) 4, 5
- Known MRSA colonization or prior MRSA infection 5, 6
- Systemic inflammatory response syndrome (SIRS) with fever, tachycardia, or altered mental status 1, 5
- Failure to respond to beta-lactam therapy after 48–72 hours 1, 5
In the absence of these risk factors, MRSA is an uncommon cause of typical cellulitis even in high-prevalence settings, and routine MRSA coverage represents overtreatment. 1, 2
Oral MRSA-Active Regimens for Outpatient Use
When MRSA coverage is required, choose one of the following:
For Purulent Cellulitis (Monotherapy Options)
- Clindamycin 10–13 mg/kg/dose every 6–8 hours (maximum 40 mg/kg/day) provides single-agent coverage for both streptococci and MRSA, but use only if local MRSA clindamycin resistance rates are <10% 4, 5
- Trimethoprim-sulfamethoxazole (TMP-SMX) 4–6 mg/kg/dose (based on TMP component) twice daily covers MRSA but must be combined with a beta-lactam (cephalexin or amoxicillin) for streptococcal coverage 4, 5
For Non-Purulent Cellulitis Requiring MRSA Coverage
- Combination therapy is mandatory: TMP-SMX 4–6 mg/kg/dose twice daily PLUS cephalexin 25–50 mg/kg/day divided every 6 hours 4, 5
- Doxycycline 2 mg/kg/dose twice daily (maximum 100 mg per dose) PLUS a beta-lactam is appropriate for children ≥8 years and <45 kg, but tetracyclines are absolutely contraindicated in children <8 years due to tooth discoloration and bone growth effects 4, 1
Intravenous Therapy for Severe or Complicated Cellulitis
Hospitalization with IV antibiotics is indicated for:
- Systemic toxicity (fever >38°C, hypotension, altered mental status, tachycardia) 1, 5
- Age <6 months with moderate-to-severe disease 7
- Rapidly progressive infection or suspected necrotizing fasciitis 1, 5
- Failure of outpatient oral therapy 1, 5
- Severe immunocompromise or neutropenia 1
IV Antibiotic Regimens
For hospitalized children with complicated cellulitis:
- Vancomycin 15 mg/kg IV every 6 hours is first-line therapy (A-II evidence) 4, 5
- Clindamycin 10–13 mg/kg/dose IV every 6–8 hours (maximum 40 mg/kg/day) is an option for stable children without ongoing bacteremia if local clindamycin resistance is <10%, with transition to oral therapy if the strain is susceptible 4, 7
- Linezolid 10 mg/kg/dose IV every 8 hours for children <12 years (600 mg IV twice daily for children ≥12 years) is an alternative 4, 7
- For severe cellulitis with systemic toxicity or suspected necrotizing fasciitis, use vancomycin 15 mg/kg IV every 6 hours PLUS piperacillin-tazobactam 100 mg/kg/dose (based on piperacillin component) IV every 6–8 hours for broad-spectrum polymicrobial coverage 1, 5
Treatment duration for complicated infections is 7–14 days, individualized based on clinical response. 4, 7
Topical Therapy for Minor Infections
For children with minor skin infections such as impetigo or secondarily infected lesions (eczema, ulcers, lacerations), mupirocin 2% topical ointment applied three times daily is effective. 4, 7
Critical Pitfalls to Avoid
- Never use doxycycline or TMP-SMX as monotherapy for typical cellulitis; these agents lack reliable activity against beta-hemolytic streptococci, which cause the majority of pediatric cellulitis cases 4, 5
- Do not reflexively add MRSA coverage for all cellulitis cases; beta-lactam monotherapy achieves 96% success in typical non-purulent cellulitis 1, 2
- Avoid tetracyclines (doxycycline, minocycline) in children <8 years due to permanent tooth discoloration and impaired bone growth 4, 1
- Do not extend treatment to 10–14 days based on residual erythema alone; 5 days is adequate for uncomplicated cases with clinical improvement 1
- Failure to drain associated abscesses leads to treatment failure regardless of antibiotic choice; incision and drainage is the primary treatment for purulent collections 4, 7
Reassessment and Treatment Failure
Reassess the child clinically at 48–72 hours after initiating therapy. 1, 5
If no improvement in warmth, tenderness, or erythema:
- Consider inadequate drainage if an abscess is present (obtain ultrasound if clinically uncertain) 1
- Switch to MRSA-active therapy if not already prescribed 1, 5
- Evaluate for deeper infection (necrotizing fasciitis, osteomyelitis) or alternative diagnoses (venous stasis, contact dermatitis, erythema migrans) 1, 2
- Obtain blood cultures and consider tissue aspiration or biopsy in high-risk populations or treatment failures 1
Adjunctive Measures
- Elevate the affected extremity above heart level for at least 30 minutes three times daily to promote gravity drainage of edema and inflammatory substances 1
- Examine interdigital toe spaces for tinea pedis, fissuring, or maceration and treat these conditions to eradicate colonization and reduce recurrent infection 1
- Address predisposing conditions including chronic edema, venous insufficiency, and eczema 1, 6