In a child with fever, irritability and an enlarging red, warm, painful tender swelling of the lower left leg without abscess, stable vital signs and no systemic manifestations, what is the most appropriate management: oral flucloxacillin with topical antibiotics, oral flucloxacillin with follow‑up, or intravenous antibiotics with surgical consultation?

Management of Enlarging Cellulitis in a Stable Child

This child requires IV antibiotics with surgical consultation (Option C). Despite stable vital signs, the enlarging nature of the infection without response to initial therapy signals potential deeper involvement that mandates escalation of care and surgical evaluation.

Risk Stratification and Red Flags

The enlarging cellulitis despite presumed initial management is a critical warning sign. The Infectious Diseases Society of America recommends prompt surgical consultation for patients with aggressive infections or suspicion of necrotizing fasciitis, even before systemic toxicity develops 1. Key features demanding heightened concern include:

• Rapidly progressive or enlarging erythema despite appropriate antibiotics suggests either resistant organisms or deeper infection 1
• Absence of pus/abscess does NOT exclude necrotizing infection—necrotizing fasciitis often lacks superficial purulence initially 1
• Stable vitals can be misleading in children—they compensate longer than adults before decompensating 1

Why IV Antibiotics Are Mandatory

Oral flucloxacillin alone (Options A and B) is inadequate for spreading cellulitis in children. The evidence is clear:

• Hospitalization is recommended when outpatient treatment is failing (moderate or severe nonpurulent cellulitis) 1
• Children with spreading cellulitis require close monitoring that cannot be achieved with oral outpatient therapy alone 2
• IV ceftriaxone has been proven non-inferior to IV flucloxacillin for moderate-to-severe pediatric cellulitis, with treatment failure rates of only 2% versus 7% respectively 3
• Home IV therapy is an option ONLY after initial stabilization and response verification—not as first-line for enlarging infection 3, 4

Surgical Consultation Is Non-Negotiable

The enlarging nature of this infection mandates surgical evaluation to exclude necrotizing fasciitis or deep space infection. Critical considerations include:

• Necrotizing fasciitis can present without systemic toxicity initially—severe pain out of proportion, rapid progression, or "wooden-hard" tissues are late findings 1, 5
• Surgical exploration may be both diagnostic and therapeutic if deeper infection is present 1
• Delay in surgical consultation for necrotizing infections increases mortality—these progress rapidly and require debridement 1, 5

Recommended Treatment Algorithm

Immediate management should proceed as follows:

1. Admit for IV antibiotics (ceftriaxone 50 mg/kg once daily OR flucloxacillin 50 mg/kg every 6 hours) 3
2. Obtain urgent surgical consultation to evaluate for deeper infection 1
3. Mark the borders of erythema to monitor progression over the next 12-24 hours 2
4. Reassess within 24-48 hours to verify clinical response 5
5. If no improvement or worsening occurs, escalate to broad-spectrum coverage (vancomycin plus piperacillin-tazobactam) and repeat surgical evaluation 1, 5

Why Oral Therapy Fails Here

Options A and B (oral flucloxacillin ± topical antibiotics) represent dangerous undertreatment:

• Topical antibiotics have NO role in cellulitis management—they do not penetrate to the site of infection 1
• Oral antibiotics are appropriate ONLY for mild, non-spreading cellulitis in stable outpatients with reliable follow-up 1, 2
• This child's enlarging infection indicates treatment failure requiring escalation, not continuation of the same approach 1, 5
• Beta-lactam monotherapy succeeds in 96% of typical cellulitis—failure suggests either resistant organisms or deeper infection 5

Common Pitfalls to Avoid

• Never assume stable vitals mean stable infection—children compensate until sudden decompensation 1
• Never delay surgical consultation when infection is spreading—necrotizing fasciitis can be fatal if debridement is delayed 1
• Never use topical antibiotics for cellulitis—they are ineffective and delay appropriate systemic therapy 1
• Never continue ineffective antibiotics beyond 48 hours—progression despite therapy indicates resistant organisms or deeper infection 5

Adjunctive Measures

Once IV antibiotics are initiated, essential supportive care includes:

• Elevate the affected leg above heart level to promote drainage 5
• Examine interdigital spaces for tinea pedis or toe web abnormalities that may serve as portals of entry 1, 5
• Monitor for signs of necrotizing infection: severe pain out of proportion, skin anesthesia, bullous changes, or gas in tissues 1, 5