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24 Cards in this Set
- Front
- Back
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What is necrotizing fascciitis?
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Necrotizing fasciitis is a deep infection of subcutaneous tissue that results in progressive destruction of fascia and fat but may spare the skin.
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Which tissue layers are affected by necrotizing fasciitis?
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Subcutaneous fat and fascia
Skin itself often spared |
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What are the different types of necrotizing fasciitis?
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2 clinical types:
Type I necrotizing fasciitis Type II necrotizing fasciitis |
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What is the principle difference between type I and type II necrotizing fasciitis?
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Type I is polymicrobial
Type II is monomicrobial |
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How many pathogenic bacterial species are usually isolated in type I necrotizing fasciitis?
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4-5
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Name 3 important clinical conditions associated with type I necrotizing fasciitis.
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1) Diabetes mellitus
2) Cervical necrotizing fasciitis, including Ludwig's Angina 3) Fournier's gangrene |
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In a diabetic with cellulitis, what signs/symptoms might lead you to suspect necrotizing fasciitis?
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Systemic signs of infection such as tachycardia, leukocytosis, marked hyperglycemia, or acidosis
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Name 2 common precipitants of cervical necrotizing fasciitis.
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1) Breach of the integrity of mucous membranes after surgery or instrumentation
2) Odontogenic infection |
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What is Ludwig's Angina?
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Ludwig's angina is a bilateral infection of the submandibular space that consists of two compartments in the floor of the mouth, the sublingual space and the submylohyoid (also known as submaxillary) space
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What is Fournier's gangrene?
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Type I necrotizing fasciitis in the perineal area
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Which bacteria causes type II necrotizing fasciitis?
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Classically, type II nec. fasc. is caused by Group A streptococci (GAS), also called Strep. pyogenes
Occasionally, however, the responsible organism is MRSA. |
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What was the old name for type II necrotizing fasciitis?
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Streptococcal gangrene
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Name a common infection that predisposes to type II necrotizing fasciitis.
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Varicella (chicken pox)
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Name the severe complication associated with type II necrotizing fascciitis.
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Streptococcal toxic shock syndrome
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Describe the pathogenesis of streptococcal toxic shock syndrome.
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Group A streptococcal TSS, like staphylococcal toxic syndrome, is mediated by toxins that act as superantigens.
Superantigens activate the immune system by bypassing the usual antigen-mediated immune response sequence resulting in the release of large quantities of inflammatory cytokines. The cytokines cause capillary leak and tissue damage, leading to shock and multiorgan failure. |
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Describe the clinical manifestation of necrotizing fasciitis.
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Unexplained pain, pain out of proportion
-increases rapidly over time -may be absent in patients with diabetes due to neuropathy -Erythema may or may not be present -Blister and bullae formation, with or without erythema -Signs of systemic toxicity (fever, hyperglycemia, acidosis) |
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What's on the differential diagnosis for necrotizing fasciitis?
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Cellulitis, gas gangrene, pyomyositis, myositis
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How is the definitive diagnosis of necrotizing fasciitis made?
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Surgical exploration
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What are the three broad strategies of intervention for a patient with necrotizing fasciitis?
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1) Aggressive surgical debridement
2) Fluid resuscitation and vasopressors 3) Systemic antibiotics |
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Which antibiotic is used to treat type I necrotizing fasciitis?
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Definitive treatment relies of Gram-stain and culture
In the meantime, empiric therapy consistis of ampicillin plus clindamycin |
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Which antibiotic is used to treat type II necrotizing fasciitis?
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Penicillin G
+ Clindamycin + Vancomycin if MRSA is suspected |
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Why is clindamycin required to treat type II necrotizing fasciitis?
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Penicillin failure in these infections is probably due to a reduction in bacterial expression of critical penicillin binding proteins during the stationary growth phase of these bacteria
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What therapy can be given to combat streptococcal exotoxins?
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Immunoglobulin therapy
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What is the mortality of necrotizing fasciitis?
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Around 30%
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