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Necrotizing Fasciitis

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Necrotizing Fasciitis Dolan Wenner, D.O. Internal Medicine Lecture Series 1/31/07 Necrotizing Fasciitis Definition commonly referred to as flesh-eating ... – PowerPoint PPT presentation

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Title: Necrotizing Fasciitis


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

2
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)

3
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

4
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

5
Pathophysiology
  • Deep infection can cause
  • Vascular occlusion
  • Ischemia
  • Tissue necrosis
  • Nerve damage
  • Septicemia (systemic toxicity)

6
Necrotizing Fasciitis syndromes
  • Type I (polymicrobial)
  • Type II group A beta-steoptococcal
  • Type III gas gangrene (clostridial myonecrosis)

7
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

20
Lab Studies
  • Elevated WBCs
  • Hyponatremia
  • Elevated BUN
  • Anemia
  • Hypocalcemia
  • Acidosis
  • Thrombocytopenia
  • Prolonged PT associated with higher mortality
    rate

21
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

28
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

29
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

30
NF Complications
  • Sepsis and renal failure
  • Metastatic plaques may occur
  • Septicemia leads to severe system toxicity and
    rapid death unless treated quickly and
    appropriately

31
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

32
Thank you!
33
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

34
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

35
Question 2
  • What test is considered the gold standard for
    diagnosis of necrotizing fasciitis?
  • MRI
  • CT scan
  • Excisional deep tissue biopsy
  • Cultures

36
Question 2
  • What test is considered the gold standard for
    diagnosis of necrotizing fasciitis?
  • MRI
  • CT scan
  • Excisional deep tissue biopsy
  • Cultures

37
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

38
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

39
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