Necrotizing Fasciitis

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Necrotizing Fasciitis

• Dolan Wenner, D.O.
• Internal Medicine Lecture Series
• 1/31/07

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Necrotizing Fasciitis

• Definition commonly referred to as
  flesh-eating bacteria, it is a rare infection
  of the deeper layers of the skin and subcutaneous
  tissue (fascia)

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Organisms

• Most common associated organism is group A
  beta-hemolytic streptococci
• Other isolated organisms Staph. aureus,
  Clostridium perfringens, Staph. Epidermidis,
  enterococci, Enterobacteriaceae species, E. coli,
  Proteus mirabilis, Klebsiella pneumonia,
  Pseudomonas aeruginosa, Bacteroides/Prevotella
  species, anaerobic gram-positive cocci

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Pathophysiology

• Organisms spread from the subcutaneous tissue
  along the superficial and deep fascial planes ?
  facilitated by bacterial enzymes and toxins
• M1 and M3 surface proteins increase adherence
  of streptococci to the tissues, also protects
  bacteria against neutrophilic phagocytosis
• Streptococcal pyrogenic exotoxins (SPEs) A, B, C
  and streptococcal superantigens (SSA) lead to
  the release of cytokines and produce clinical
  signs such as hypotension

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Pathophysiology

• Deep infection can cause
• Vascular occlusion
• Ischemia
• Tissue necrosis
• Nerve damage
• Septicemia (systemic toxicity)

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Necrotizing Fasciitis syndromes

• Type I (polymicrobial)
• Type II group A beta-steoptococcal
• Type III gas gangrene (clostridial myonecrosis)

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NF Type I

• Polymicrobial
• Typically occurs after surgery or trauma
• Can be mistaken for simple wound cellulitis
• May also be observed with urogenital or
  anogenital infections
• Aerobic and anearobic bacteria usually found in
  combination ? work synergistically
• Variant of NF saltwater NF, usually minor skin
  would contaminated with saltwater that contains
  Vibrio species

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NF Type II

• So-called flesh-eating bacterial infection
• Monomicrobial
• Caused by group A beta-streptococcus
• Varicella infection and use of non-steroidal
  anti-inflammatory drugs may be predisposing
  factors

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NF Type III

• Gas gangrene (clostridial myonecrosis)
• Usually caused by Clostridium perfringens
• When this type occurs spontaneously, Clostridium
  septicum most likely etiologic agent ? usually
  occur in association with colon CA or leukemia
• Skeletal muscle infection may be associated with
  recent surgery or trauma

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NF History and Physical Exam

• History
• Fever and chills
• Erythema noted
• Supralesional vesiculation or bullae formation
• Serosanguinous fluid drainage
• Recent history of skin biopsy, illicit drug use,
  frostbite, chronic venous stasis ulcers, open
  bone fractures, insect bites, surgical wounds,
  and skin abcesses
• History of Diabetes

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NF History and Physical Exam

• Physical Exam
• Rapidly advancing erythema
• Painless ulcers
• Black necrotic eschar may be evident at the
  borders of the affected areas
• Vesiculation or bullae formation may be noted
• Sepsis/shock
• Gas may be evident (crepitus)
• Pain out of proportion to exam

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Cellulitis vs. NF

• The following may suggest NF
• Rapid progression
• Poor therapeutic response
• Blistering necrosis
• Cyanosis
• Extreme local tenderness
• High temperature
• Tachycardia
• Hypotension
• Altered level of consciousness

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Lab Studies

• Elevated WBCs
• Hyponatremia
• Elevated BUN
• Anemia
• Hypocalcemia
• Acidosis
• Thrombocytopenia
• Prolonged PT associated with higher mortality
  rate

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Imaging Studies

• Standard radiographs little value unless free
  air is depicted, as with gas-forming infections
• CT can show subcutaneous air
• T2-weighted MRIs may show well-defined regions of
  high signal intensity in the deep tissues ?
  sensitivity exceeds specificity
• CT and MRI may be useful in directing rapid
  surgical debridement

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Other Tests

• Excisional deep tissue biopsy is gold standard
• Gram staining (can help delineate between Type I
  and Type II)
• Cultures

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Treatment

• Transfer pt to ICU or Surgical ICU
• Maintain hemodynamic parameters
• Surgical Debridement
• Combination antibiotic therapy
• Single antibiotic therapy
• Vancomycin
• Hyperbaric oxygen (HBO) ? may reduce mortality
  rate, but no literature to support
• IVIG ? anecdotal evidence

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Treatment

• Surgical Debridement
• Incisions should be deep and extend beyond the
  areas of necrosis until viable tissue is reached
• Wound should be well irrigated
• Hemostasis should be maintained
• Wound should be kept open
• Debridement and evaluations should be repeated on
  a daily basis

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Treatment

• Antimicrobial therapy
• Ampicillin (Principen, Omnipen)
• Gentamicin (Garamycin, Jenamicin)
• Clindamycin (Cleocin)
• Metronidazole (Flagyl)
• Imipenem and cilastatin (Primaxin)
• Ampicillin and sulbactam (Unasyn)
• Piperacillin-tazobactam (Zosyn)
• Vancomycin
• Amphotericin B

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NF Complications

• Sepsis and renal failure
• Metastatic plaques may occur
• Septicemia leads to severe system toxicity and
  rapid death unless treated quickly and
  appropriately

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NF - Prognosis

• Poor prognosis linked to certain streptococcal
  strains
• Mortality rate can be as high as 25
• Cases of NF with renal failure and sepsis have
  mortality rate as high as 70
• Early recognition and appropriate treatment can
  help ensure better prognosis

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Thank you!
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Question 1

• What is the most common organism associated with
  necrotizing fasciitis (flesh-eating disease)?
• E. coli
• Group A beta-hemolytic streptococci
• Pseudomonas aeruginosa
• Proteus mirabilis

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Question 1

• What is the most common organism associated with
  necrotizing fasciitis (flesh-eating disease)?
• E. coli
• Group A beta-hemolytic streptococci
• Pseudomonas aeruginosa
• Proteus mirabilis

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Question 2

• What test is considered the gold standard for
  diagnosis of necrotizing fasciitis?
• MRI
• CT scan
• Excisional deep tissue biopsy
• Cultures

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Question 2

• What test is considered the gold standard for
  diagnosis of necrotizing fasciitis?
• MRI
• CT scan
• Excisional deep tissue biopsy
• Cultures

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Question 3

• What is the organism that is most commonly
  associated with Type III necrotizing fasciitis?
• Group A beta-hemolytic streptococci
• Proteus mirabilis
• Clostridium perfringens
• Staphylococcus aureus

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Question 3

• What is the organism that is most commonly
  associated with Type III necrotizing fasciitis?
• Group A beta-hemolytic streptococci
• Proteus mirabilis
• Clostridium perfringens
• Staphylococcus aureus

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The End