What is the initial step in management of a 10‑year‑old with tender, warm, erythematous swelling of the left leg and low‑grade fever?

Initial Management of Pediatric Lower Extremity Cellulitis

In a 10-year-old with tender, warm, erythematous leg swelling and low-grade fever without systemic toxicity, the initial step is oral antibiotics with close follow-up (Option A).

Clinical Assessment and Risk Stratification

This presentation is consistent with uncomplicated cellulitis—a bacterial infection of the dermis and subcutaneous tissue typically caused by Gram-positive organisms, particularly Streptococcus pyogenes and Staphylococcus aureus 1. The key distinguishing features that support outpatient oral therapy include:

• Well-appearing child without signs of systemic inflammatory response (no high fever >38.5°C, no hypotension, no altered mental status) 1
• Absence of deeper tissue involvement (no abscess, no signs suggesting necrotizing fasciitis or osteomyelitis) 1
• No immunocompromise or significant comorbidities 1

The 2018 WSES/SIS-E consensus explicitly states that cellulitis should be managed with antibiotics against Gram-positive bacteria, and that oral beta-lactams are sufficient for early, mild cellulitis in areas where community-acquired MRSA is not prevalent 1.

Why Oral Antibiotics Are Appropriate

Oral first-generation cephalosporins (cephalexin) are the most commonly prescribed and effective agents for uncomplicated pediatric cellulitis 2. In a retrospective study of 269 children with nonfacial cellulitis, oral cephalexin had only an 8.9% treatment failure rate and required significantly fewer ED visits (1.4 ± 1 visits) and less time in the emergency department (164 ± 139 minutes) compared to intravenous therapy 2.

Recent consensus among emergency medicine and hospital medicine providers identified specific features warranting intravenous therapy—including fevers/chills, lymphangitis, and functional impairment—none of which are prominently described in this case 3. The presence of only low-grade fever without systemic toxicity does not meet criteria for intravenous administration 3.

Why Other Options Are Inappropriate

Option B (Warm Compressions and Observe)

Simple observation without antibiotics is inadequate because this child has clear signs of bacterial infection (erythema, warmth, tenderness, fever) 1. The WSES guidelines state that cellulitis requires antibiotic therapy against Gram-positive bacteria, not observation alone 1. Delaying antibiotic treatment risks progression to deeper infection or systemic complications 1.

Option C (X-ray)

Plain radiographs are not indicated as the initial step in uncomplicated cellulitis 1. The ACR Appropriateness Criteria note that radiographs have low sensitivity for soft tissue infections and are typically normal in early infection 1. X-rays become relevant only when there is concern for osteomyelitis (bone pain, inability to bear weight, prolonged symptoms >7 days) or when evaluating for gas in tissues suggesting necrotizing infection 1. This child's 10-day history without these features does not warrant imaging before initiating antibiotics 1.

Option D (IV Antibiotics)

Intravenous antibiotics are reserved for complicated cellulitis with systemic inflammatory response criteria, signs of organ dysfunction, deeper tissue involvement (abscess, necrotizing fasciitis, osteomyelitis), or failure of oral therapy 1, 3. The WSES guidelines specify that IV antibiotics are indicated when patients have hypotension, oliguria, decreased mental alertness, or are immunocompromised—none of which apply here 1. Studies demonstrate that outpatient IV therapy (when needed) requires significantly more ED time (521 ± 287 minutes) and visits (3.4 ± 2.8) compared to oral therapy 2.

Recommended Management Algorithm

1. Prescribe oral cephalexin 25-50 mg/kg/day divided into 2-4 doses (maximum 4 g/day) for 5-10 days 4, 2
2. Mark the borders of erythema with a pen to monitor progression 1
3. Arrange close follow-up within 24-48 hours to assess response 3
4. Instruct parents to return immediately if the child develops high fever (>38.5°C), worsening erythema, functional impairment, systemic symptoms, or failure to improve within 48 hours 1, 3
5. Consider MRSA coverage (clindamycin or trimethoprim-sulfamethoxazole) if the patient fails to respond to first-line therapy or has risk factors for CA-MRSA 1

Critical Pitfalls to Avoid

• Do not delay antibiotics while obtaining imaging in uncomplicated cases 1
• Do not assume IV therapy is superior to oral antibiotics in well-appearing children without systemic toxicity 2, 5
• Do not overlook the need for close follow-up—treatment failure occurs in 8-14% of cases and requires reassessment 2, 3
• Do not miss deeper infections—if the child has bone tenderness, inability to bear weight, or symptoms persisting >7 days despite antibiotics, obtain imaging to evaluate for osteomyelitis 1