Necrotizing soft tissue infections
Background
- Includes necrotizing forms of cellulitis, myositis, and fasciitis
- Two types:
- Type 1: polymicrobial infection
- Type 2: group A strep
- May occur in healthy individuals with no PMH
- May occur via hematogenous spread from throat to site of blunt trauma
Necrotizing Fasciitis
Risk Factors
- DM
- Drug use
- Obesity
- Immunosuppression
- Recent surgery
- Traumatic wounds
Clinical Features
- Skin exam
- Erythema(without sharp margins)
- Exquisitely tender (pain out of proportion to exam)
- Skip lesions
- Hemorrhagic bullae
- May be preceded by skin anesthesia (destruction of superficial nerves)
- Crepitus (in type I infections)
- Swelling/edema may produce compartment syndrome
- Constitutional
- Fever
- Tachycardia
- Systemic toxicity
Necrotizing Myositis
- Much rarer than nec fasc
- May be preceded by skin abrasions, blunt trauma, heavy exercise
- Most patients are otherwise healthy (DM and other underlying conditions do not appear to increase risk)
Necrotizing Cellulitis
- Pts are often much less toxic compared with nec fasc/nec myo
- Two types:
- Anaerobic infection (clostridial and nonclostridial)
- Meleney's synergistic gangrene
- Rare infection that occurs in postop pts
- Characterized by slowly expanding indolent ulceration that is confined to superficial fascia
- Results from synergistic interaction between S. aureus and microaerophilic streptococci
Risk Factors
- Trauma
- Surgical contamination
- Spread of infection from bowel to perineum, abdominal wall, or lower extremities
Clinical Features
- Thin, dark, sometimes foul-smelling wound drainage (often containing fat globules)
- Tissue gas formation (crepitus)
Management
- Surgical exploration and debridement required to distinguish between anaerobic cellulitis and fasciitis or myonecrosis
Source
- UpToDate