A 38-year-old woman presents to the clinic with a 2-day history of fever (39°C) and a sharply demarcated, raised, bright red patch on her left cheek. The lesion has a "slapped cheek" appearance with a well-defined border. There is associated cervical lymphadenopathy and mild systemic toxicity. The skin is intact with no vesicles or pustules. She denies any recent trauma or insect bite. On examination, the erythema does not blanch completely with pressure. Which of the following is the most appropriate initial management?

Explanation

## Clinical Diagnosis: Erysipelas ### Diagnostic Features **Key Point:** Erysipelas is a superficial cellulitis caused by *Streptococcus pyogenes* (Group A Streptococcus), characterized by **sharply demarcated, raised, bright red borders** with rapid onset and systemic toxicity. | Feature | Erysipelas | Cellulitis | |---------|---|---| | **Margin** | Sharp, raised, well-demarcated | Poorly demarcated, indistinct | | **Depth** | Superficial (dermis + upper subdermis) | Deep (dermis + subcutaneous) | | **Lymphangitis** | Prominent | Uncommon | | **Lymphadenopathy** | Common | Uncommon | | **Causative organism** | *S. pyogenes* (GAS) | *S. aureus* > GAS | | **Onset** | Rapid (12–48 hours) | Gradual (3–5 days) | | **Systemic toxicity** | Marked | Variable | ### Why This Is Erysipelas 1. **Sharply demarcated, raised borders** — pathognomonic for erysipelas 2. **"Slapped cheek" appearance** — classic facial presentation 3. **Rapid onset** (2 days) with **high fever** (39°C) 4. **Cervical lymphadenopathy** — common in facial erysipelas 5. **Intact skin** with **no vesicles/pustules** — rules out herpes zoster or impetigo 6. **Non-blanching erythema** — indicates dermal inflammation ### Appropriate Management **High-Yield:** Erysipelas is caused by *S. pyogenes*, which is **highly susceptible to penicillin**. First-line treatment is: - **Oral penicillin V** (250 mg QID for 10 days) — **preferred for mild-to-moderate cases** - **Oral cephalexin** (500 mg QID for 10 days) — alternative for penicillin-allergic patients - **IV ceftriaxone or IV penicillin** — reserved for severe cases, systemic toxicity, or immunocompromised patients **Clinical Pearl:** This patient has **mild-to-moderate erysipelas** (fever, systemic toxicity, but no signs of sepsis or necrotizing infection). Oral penicillin V is sufficient and is the standard of care. ### Why Each Distractor Is Wrong **Topical mupirocin:** Erysipelas is a **systemic infection** with bacteremia — topical therapy alone is inadequate. Systemic antibiotics are mandatory. **Amoxicillin–clavulanate:** While this covers *S. aureus*, it is **not first-line for erysipelas**. Penicillin or cephalexin are preferred because: - *S. pyogenes* is uniformly penicillin-susceptible - Clavulanate adds no benefit against GAS - Unnecessary broad-spectrum coverage increases resistance risk **IV ceftriaxone:** Reserved for **severe erysipelas** with: - Sepsis or hemodynamic instability - Immunocompromised host (HIV, chemotherapy) - Facial erysipelas with risk of cavernous sinus thrombosis - Inability to tolerate oral medications This patient is hemodynamically stable with mild-to-moderate disease — oral therapy is appropriate. ### Treatment Duration **Key Point:** Erysipelas requires **10–14 days** of antibiotics to prevent recurrence (up to 20% relapse rate if undertreated). [cite:Park 26e Ch 8; Harrison 21e Ch 119]