Necrotizing fasciitis (hemolytic streptococcal gangrene) is marked by severe pain and systemic toxicity with infection into fascial planes of extremity, perianal region, or genitals. Characteristic is skin necrosis (bullae, tense edema, and/or blue-black discoloration).
CASES/YEAR
12,000 (US); 240,000 (Global)
OTHER NAMES
Fournier's gangrene; Hemolytic streptococcal gangrene; Necrotizing subcutaneous infection;
INCUBATION
Varies from rapid onset (superficial infection) to slower onset (infection of deeper structures); [Harrisons, p. 536] Estimated: 1-5 days;
INITIAL SYMPTOMS
Severe pain and unexplained fever; [Harrisons, p. 436] Severe pain & systemic toxicity with infection into fascial planes of extremity, perianal region, or genitals; Skin necrosis (bullae, tense edema, and/or blue-black discoloration); [ABX Guide]
PRECAUTIONS
Standard; "Contact Precautions when cases clustered temporally." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
"Exam is notable for high fever and pain out of proportion to physical findings; the infected area is red, hot, shiny, and exquisitely tender." [Harrisons, 18th Ed, p. 131] After initial pain and fever, patients may develop anesthesia because of ischemia to peripheral nerves. In final stages, patients develop shock and multiorgan failure. [Harrisons, p. 573] Common laboratory abnormalities are leukocytosis, thrombocytopenia, azotemia, and elevated creatine phosphokinase. Risk factors are diabetes, peripheral vascular disease, cirrhosis, and corticosteroid therapy. About 1/2 of patients with streptococcal toxic shock syndrome have necrotizing fasciitis. [PPID, p. 1302] Overlying skin may contain petechiae or bullae. [PPID, p. 1311] The overlying skin may appear normal, and pain out of proportion to that expected from the exam is a distinctive feature of necrotizing fasciitis. This is an infection of subcutaneous tissue and fascia with relative sparing of muscle. One half of patients have no history of an antecedent skin lesion or injury at the site of infection. [Cecil, p. 1863,1873] Classic signs are purple bullae, skin sloughing, and progressive toxicity. "Strains of MRSA that produce the Panton-Valentine leukocidin (PVL) toxin have been reported to cause necrotizing fasciitis." [Harrison ID, p. 260] See "Gas gangrene."
DIAGNOSTIC
Fascial plane infection at the time of surgery or by CT scan or MRI; Use Gram stain and cultures to distinguish 3 main types (Group A streptococci; Mixed anaerobes + coliforms (most common); and MRSA; [ABX Guide]
SIGNS & SYMPTOMS
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>fever
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>myalgia
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G diarrhea
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H leukocytosis
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H lymphadenopathy
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H thrombocytopenia
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N confusion, delirium
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N lethargy
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S lymphangitis
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S pustule
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S skin blister or vesicles
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*acute renal failure
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*sepsis
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*shock
ENTRY
Skin or Mucous Membranes (Includes Conjunctiva)
RISK FACTORS
- Cancer patients
- Injection drug users
TREATMENT
"Emergent surgical exploration to deep fascia and muscle, with removal of necrotic tissue, is essential." [Harrisons, p. 436] May require daily debridements. [ABX Guide]
REFERENCES FOR CASES/YEAR
1. (US) In the US, 0.04 cases per 1000; [Gorbach, p. 284] Calculate: 0.04 x 300,000 = 12,000;;
2. (Global) 20 X US cases/yr;