## Distinguishing ABSSSI from Impetigo ### Anatomical Depth and Systemic Impact | Feature | Impetigo | ABSSSI (Cellulitis/Abscess) | |---------|----------|-----------------------------| | **Depth of infection** | Superficial epidermis only | Dermis and/or subcutaneous tissue | | **Systemic manifestations** | Absent or minimal | Fever, malaise, lymphadenopathy, bacteremia | | **Erythema pattern** | Well-demarcated, localized crusts | Poorly demarcated, spreading erythema | | **Edema** | Minimal | Marked, with induration | | **Purulent drainage** | Minimal or absent | Often present (abscess formation) | | **Bacteremia risk** | Rare (<1%) | Common (5–15% in cellulitis) | | **Systemic toxicity** | None | Present (fever, chills, malaise) | ### Key Point: **ABSSSI involves deeper tissue layers (dermis and subcutaneous tissue) and is accompanied by systemic signs (fever, lymphadenopathy, bacteremia).** Impetigo remains confined to the epidermis with minimal or no systemic manifestations. ### Clinical Pearl: The presence of **purulent drainage with systemic signs and deeper tissue involvement** in this IVDU patient with MRSA bacteremia indicates ABSSSI (likely abscess or cellulitis), not impetigo. Impetigo, even when caused by S. aureus, does not typically cause bacteremia or deep tissue involvement. ### High-Yield: ABSSI classification requires involvement of dermis/subcutaneous tissue PLUS systemic signs (fever, elevated WBC, tachycardia) or signs of spreading infection. Impetigo is a superficial, self-limited condition without these systemic features. ### Mnemonic: **DEEP TROUBLE = ABSSSI** (Deeper layers, Systemic signs, Purulent drainage) **SURFACE ONLY = Impetigo** (Superficial epidermis, No systemic signs) 
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