Necrotizing fasciitis is a life-threatening subcutaneous soft-tissue infection that requires a high index of suspicion for diagnosis.
Infection may be polymicrobial in etiology (type I) due to mixed anaerobic/facultative anaerobic organisms, or due to a single organism (type II), most commonly Streptococcus pyogenes, also called group A streptococcus.
Necrotizing fasciitis should be suspected in any patient with a soft-tissue infection accompanied by prominent pain and/or anesthesia over the infected area, or signs and symptoms of systemic toxicity.
Signs that raise suspicion for necrotizing fasciitis include the presence of hypotension and/or elevated creatinine, elevated creatine kinase, elevated C-reactive protein (>13 mg/L), elevated white blood cell count with marked left shift, and/or low serum bicarbonate.
No laboratory or imaging studies, alone or in combination, are sufficiently sensitive and specific to definitively diagnose or rule out necrotizing fasciitis.
An urgent surgical consultation should be obtained as soon as the diagnosis is suspected. Treatment should not be delayed while awaiting microbiologic and imaging investigations.
Definitive treatment is surgical debridement, repeated as necessary. Antibiotic therapy is crucial, but is considered adjunctive to surgical management. Empiric antibiotics should cover major bacterial etiologic agents, and group A streptococcal toxin production that can accompany type II necrotizing fasciitis.
Necrotizing fasciitis is a life-threatening subcutaneous soft-tissue infection that may extend to the deep fascia, but not into the underlying muscle. The causal organisms may be aerobic, anaerobic, or mixed flora. Two main clinical forms exist. Type I necrotizing fasciitis is a polymicrobial infection with an anaerobe such as Bacteroides or Peptostreptococcus and a facultative anaerobe such as certain Enterobacterales or non-group A streptococcus. Type II necrotizing fasciitis is most commonly a monomicrobial infection with Streptococcus pyogenes (group A streptococci). Other infectious etiologies may rarely cause a monomicrobial necrotizing infection that may be associated with specific exposures or risk factors (e.g., freshwater exposure associated with Aeromonas hydrophila, saltwater exposure or consumption of raw oysters associated with Vibrio vulnificus).
History and exam
Key diagnostic factors
- history of traumatic or nontraumatic cutaneous lesion
- anesthesia or severe pain over site of cellulitis
- palpitations, tachycardia, tachypnea, hypotension, and lightheadedness
- nausea and vomiting
- vesicles or bullae
- gray discoloration of skin
- edema or induration
- location of lesion
- inpatient contact with index case
- Varicella zoster infection
- cutaneous injury, surgery, trauma
- nontraumatic skin lesions
- intravenous drug use
- chronic illness
- nonsteroidal anti-inflammatory drugs (NSAIDs)
1st investigations to order
- complete blood count and differential
- serum electrolytes
- serum BUN and creatinine
- serum CRP
- serum creatine kinase (CK)
- serum lactate
- blood and tissue cultures
- Gram stain
- arterial blood gas
- radiography, CT/MRI, ultrasound
- surgical exploration
type I necrotizing fasciitis (polymicrobial)
type II necrotizing fasciitis due to group A streptococcus
type II necrotizing fasciitis due to Staphylococcus aureus
type II necrotizing fasciitis due to Vibrio vulnificus
type II necrotizing fasciitis due to Aeromonas hydrophila
type II necrotizing fasciitis due to mucorales
persistent cosmetic and functional defects after debridement
- 2018 WSES/SIS-E Consensus Conference: recommendations for the management of skin and soft-tissue infections
- Practice guidelines for the diagnosis and management of skin and soft-tissue infections
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