Necrotising fasciitis

Reviewed and revised 12 July 2015

OVERVIEW

• Necrotising fasciitis is a severe bacterial soft tissue infection marked by edema and necrosis of subcutaneous tissues with involvement of adjacent fascia and by painful red swollen skin over affected areas
• may resemble cellulitis initially but is often rapidly progressive
• commonly known as ‘flesh-eating disease’
• Fournier gangrene is a polymicrobial necrotizing fasciitis of the perineal, perianal, or genital areas

CLASSIFICATION

From Misiakos et al, 2014:

Classification of responsible pathogens according to type of infection.

Fournier gangrene is typically polymicrobial infection with aerobes and anaerobes, such as coliforms, klebsiella, streptococci, staphylococci, clostridia, bacteroids, and corynbacteria

CAUSTIVE ORGANISMS

Monomicrobial pathogens:

• Streptococci (especially Streptococcus pyogenes – Group A)
• Clostridium perfringens (gas gangrene) and other Clostridial species
• Staph aureus
• Vibrio vulnificans
• Aeronomonas hydrophila

Polymicrobial pathogens

• mixed aerobe-anaerobe bacterial flora (E.coli, Bacteroides fragillis, Strep and Staph)

RISK FACTORS

• DM
• ETOH abuse
• PVD
• renal failure
• odontogenic infection
• malignancy
• chicken pox
• local penetrating trauma or animal bite
• recent surgery (e.g. abdominal or peritoneal surgery)
• HOWEVER, Group A Strep -> has particularly affinity for young healthy patients ? no previous exposure makes it highly virulent

CLINICAL ASSESSMENT

History

• spreading erythema
• sepsis (fever, chills, myalgia)
• severe constant pain that is out of proportion to clinical findings
• cutaneous anaesthesia
• evidence of developing organ failures
• underlying risk factors (See above)
• commonly an extremity -> but can affect anywhere (e.g. perineum = Fournier gangrene)

Examination

• Local:
  • erythematous, tender, swollen
  • skin becomes smooth, shiny and tensely swollen -> darkens, patchy, blisters and bullae -> gangrene
  • a wooden-hard feel of the subcutaneous tissue
  • oedema beyond the margin of erythema
  • crepitus (gas gangrene)
• Systemic
  • fever, tachycardia
  • haemodynamic instability
• rapid spread on re-examination

INVESTIGATIONS

Investigations should not be performed if they delay definite surgical intervention in a suspected case of necrotizing fasciitis

Laboratory

• blood cultures
• FMC (leucocytosis/leukopaenia)
• elevated CRP
• Coagulation profile (DIC)
• UEC (renal failure)
• elevated CK

Imaging

• XR: gas in subcutaneous tissues
• CT: subcutaneous air
• MRI: extent of fascial necrosis seen and can guide limits of debridement

Other

• biopsy: can help differentiate between fasciitis and cellulitis
• surgery reveals the absence of normally adherent fascia to blunt dissection + watery, thin foul smelling pus in subcutaneous space

MANAGEMENT

Resuscitation

• aggressive management of septic shock if present

Specific therapy

• Extensive urgent surgical debridement (the mainstay!)
• Antimicrobial therapy
  • clindamycin and lincomycin -> theoretically suppress toxin production by streptococci (no clinical evidence)
  • penicillin is often added but is not necessary for empiric treatment
  • nosocomial infections -> vancomycin to cover MRSA (plus clindamycin or lincamycin)

Empiric

• Meropenem 1g or 25mg/kg Q8 hrly + Clindamycin 600mg or 15mg/kg Q8h

Streptococcus pyogenes

• Penicillin 1.8g or 45mg/kg Q4 hrly or Cephazolin 2g or 50mg/kg Q6 hrly + Clindamycin 600mg or  15mg/kg Q8 hrly

Clostridial infection

• Benzylpenicillin 2.4g or 60mg/kg Q4 hourly or Metronidazole 500mg or 12.5mg/kg Q8 hrly

Polymicrobial (e.g. Fournier gangrene)

• Meropenem 1g or 25mg/kg Q8 hrly

• Other therapies
  • can use lincomycin 600mg or 15mg/kg IV Q8hrly instead of clindamycin
  • hyperbaric oxygen – maybe beneficial in anaerobic gram –ve necrotising fasciitis (Concrane: “no evidence to support or refute“)
  • intravenous immunoglobulin (IVIG) 0.4 to 2 g/kg IV, for 1 or 2 doses during the first 72 hours – consider in Group A Strep necrotising fasciitis based on expert advice

Seek and treat underlying cause and complications (e.g. diabetes mellitus)

Supportive care and monitoring

Consults

• General surgeon
• ENT (if needs grommets for hyperbaric chamber)
• Infectious diseases

Disposition

• urgent transfer to operating theatre
• often need ICU admission post-operatively, may need further surgeries and often treated with hyperbaric oxyen

PROGNOSIS

• mortality 30-40% with appropriate therapy
• increased mortality in co-morbid patients
• mortality directly proportional to delay in diagnosis and treatment

References and Links

LITFL

• Eponymictionary – Fournier gangrene
• Eponymictionary – Alfred Jean Fournier (1832-1914)

Journal articles

• Levett D, Bennett MH, Millar I. Adjunctive hyperbaric oxygen for necrotizing fasciitis. Cochrane Database Syst Rev. 2015;1:CD007937. [pubmed]
• Misiakos EP, Bagias G, Patapis P, Sotiropoulos D, Kanavidis P, Machairas A. Current concepts in the management of necrotizing fasciitis. Front Surg. 2014;1:36. [pubmed]
• Puvanendran R, Huey JC, Pasupathy S. Necrotizing fasciitis. Can Fam Physician. 2009;55:(10)981-7. [pubmed]
• Thwaini A, Khan A, Malik A, et al. Fournier’s gangrene and its emergency management. Postgrad Med J. 2006;82:(970)516-9. [pubmed] [Free Full Text]

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