Necrotizing Fasciitis

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Necrotizing Fasciitis

• David Hough MSIII
• Penn State College of Medicine

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Outline

• Overview of Necrotizing Fasciitis
• Clinical/ Pathological signs
• Risk Factors
• Type 1 vs. Type 2 Necrotizing Fasciitis (NF)
• Fourneirs Gangrene
• Diagnosis
• Treatment
• Outcomes

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NF- Definition

• A subcutaneous infection of fascia and fat which
  may or may not spare the skin.

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Description of NF

• Clinical features
• Fulminant destruction of tissue
• Systemic signs of toxicity
• High rate of mortality
• Pathological features
• Extensive tissue destruction
• Thrombosis of blood vessels
• Abundant bacteria spreading along fascial planes
• Unimpressive infiltration of acute inflammatory
  cells
• Secondary to collagenases, hyaluronidases, and
  other destructive enzymes

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Clinical Signs of NF

• Fever
• Tachycardia
• Hypotension
• Tense edema around involved skin
• Disproportionate pain
• Blisters/ bullae
• Crepitus (present 10 of time)
• Subcutaneous gas
• These are all fairly specific, but have a
  sensitivity of only 10-40

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Clinical Signs of NF

• Skin findings
• May be normal, erythematous, edematous, cyanotic,
  bronzed, indurated, blistered, or frankly
  gangrenous. Generally the appearance of the skin
  underestimates the degree of underlying disease.

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Risk Factors for NF

• No true risk factors have been identified
• Conditions associated with necrotizing vs.
  non-necrotizing infections
• Drug use
• Diabetes mellitus (present in up to 60 of cases)
• Obesity
• Immunosuppresion
• Malnutrition
• HIV infection
• Alcoholism

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Considerations in NF

• Progresses rapidly from seemingly benign disease
  to extensive destruction of tissue, systemic
  toxicity, need for amputation, or death

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Necrotizing Fasciitis (NF)

• Type 1
• A mixed infection caused by aerobic and anaerobic
  bacteria. These occur most commonly after surgery
  or in individuals with diabetes and peripheral
  vascular disease.
• Type 2
• A monomicrobial infection caused primarily by
  group A streptococcus (GAS), although it is
  occasionally caused by community-associated
  methicillin-resistant Staphylococcus aureus (MRSA)

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Type 1 NF

• Primarily includes 3 categories (locations) of
  infection
• Diabetes Mellitus- infections of the feet
• Cervical necrotizing fasciitis- infection of the
  neck
• Fourniers Gangrene- infection of the perineum

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Type 1 NF

• 2/3 of cases have mixed aerobic and anaerobic
  infections
• The bugs The average case had 4.6 isolates
• Staphylococcus aureus
• Streptococci
• Enterococci
• Escherichia coli
• Peptostreptococcus
• Preveoella and Porphyromonas
• Bacteroides fragilis
• Clostridium

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Diabetes Mellitis
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Cervical Necrotizing Fasciitis
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Fourniers Gangrene (FG)

• First described by French verenologist Jean
  Alfred Fournier who witnessed a rapidly
  progressing gangrene of the penis and scrotum of
  5 previously healthy young men.
• A polymicrobial necrotizing fasciitis (NF) of the
  perinium, perianal area, or genitals. It may
  involve either men or women.

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Fourniers Gangrene

• Found in the perineal area- it is an infection
  caused by penetration of the gastrointestinal or
  urethral mucosa by bacteria.
• Characterized by an abrupt onset with severe pain
  which may spread rapidly to the anterior
  abdominal wall, gluteal muscles, or the scrotum
  and penis in males.

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Epidemiology of FG

• Not very common. On average 97 cases were
  reported each year from 1989 to 1998.
• Mostly age 30-60, although all ages have been
  reported
• Effects men 101 over females. This may be due to
  better perineal drainage in females through
  vaginal secretions.

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FG following vasectomy
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Extensive reconstruction post Fourniers Gangrene
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Diagnosis of NF

• DDx include gas gangrene, pyomyositis, and
  myositis.

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Diagnosis of NF- Labs

• Labs- use risk score
• Serum C-reactive protein gt 150 mg/L (4 points)
• WBC count 15,000 to 25,000 (1 point) or gt 25,000
  (2 points)
• Hemoglobin 11.0 to 13.5 g/dL (1 point) or lt 11
  g/dL (2 points)
• Serum sodium less than 135 meq/L (2 points)
• Serum glucose greater than 180 mg/dL (1 point)

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Diagnosis of NF- Labs

• Interpretation of Risk Score
• gt 6 should raise suspicion of NF
• gt 8 is highly predictive of NF (75-80 in one
  study with NF had scores over 8)

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Diagnosis of NF- Imaging

• Soft tissue X-ray, CT, and MRI can be helpful to
  identify gas in tissue.
• However, gas is specific, but not very sensitive.
  
• Tissue swelling that is seen could simply be from
  trauma, surgery, or postpartum

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Diagnosis of NF- Cultures

• Blood cultures are positive in 60 of patients
  with Type II NF, and 20 of patients with Type I
  NF (usually polymicrobial)
• However in Type I, blood cultures may not grow
  all organisms involved in the tissue infection
• Aspiration of bullae or skin also may not give an
  accurate representation of the infection

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Diagnosis of NF- Surgery

• Surgical exploration with sampling of deep tissue
  is the most accurate means of diagnosis.
• This also allows debridement of the infection

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Treatment of NF- Surgery

• Surgery
• Early and aggressive surgical exploration and
  debridement
• This should be done in the first 24 hours of
  symptoms
• Repeat debridement should be repeated daily until
  all necrotic tissue has been removed (typically
  2-4 times)
• Fourneirs Gangrene may require cystostomy,
  colostomy, or orchiectomy (although this is
  rare).

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Treatment of NF- Antibiotics

• Antibiotics
• Virtually 100 of patients will die on
  antibiotics without surgical debridement
• Type 1- ampicillin or ampicillin-sulbactam and
  clindamycin or metronidazole. For patients with
  prior hospitalization substitute
  ticarcillin-clavulanate or piperacillin-tazobactam
  for ampicillin-sulbactam
• Type 2- clindamycin. Add vancomycin to cover for
  MRSA

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Treatment of NF- Toxic Shock

• Type 2
• In the case of streptococcal toxic shock massive
  amounts of fluid (10-20 L/day) may be necessary
  to maintain perfusion. Pressors such as dopamine
  may also be added
• IVIG has also been used to neutralize the
  streptococcal superantigens, however no studies
  have been done to support this use

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Mortality of NF

• Type I- 21
• Type II- 14-34
• Cervical NF- 22
• Fourniers Gangrene- 22-40

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Summary

• NF can progress rapidly leading to amputation or
  death
• A degree of suspicion is necessary to get a
  patient to surgery for diagnosis and treatment
• Treatment primarily involves surgery and
  antibiotics
• Even with rapid treatment mortality remains high

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References

• www.uptodateonline.com
• Thomsen, Todd. Fourneirs Gangrene.
  http//www.emedicine.com/emerg/topic929.htm