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Necrotizing Fasciitis (Flesh Eating Disease)

From Physiopedia

Original Editors - Sara Halliday & Ashley Walker from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors -

Ashley Walker, Sara Halliday and Elaine Lonnemann  

Contents


Definition/Description

Necrotizing Fasciitis (NF) is a bacterial infection that consists of rapidly progressing necrosis of fascia and subcutaneous fat that eventually results in necrosis of the overlying skin and muscle.[1]  The most rapidly progressing type of necrotizing fasciitis is Group A, streptococcal infection, also known as flesh-eating bacteria. Necrotizing fasciits can also involve microbial infections with a singular bacteria (monomicrobial) or a combination of bacteria (polymicrobial).  Necrotizing Fasciitis can occur due to several reasons (traumatic and nontraumatic) and in a variety of patient populations. Some conditions have been found to predispose patients to the risk of infection.  Most of these conditions cause immunosuppression and include DM, malignancy, drug abuser, and chronic renal disease.[2]

The progression of the infection begins with the introduction of bacteria to the site and typically a result of trauma to the skin, however, trauma is not a necessary component. Once the infection is seeded locally, the bacteria spreads through deep fascial planes causing widespread tissue damage and infection. The spread of bacteria can cause ischemia to the area due to thrombosis occurring in blood vessels which can eventually result in gangrene. [3]

Prevalence

The number of cases reported for necrotizing fasciitis in adults is 0.40 cases per 100,000 people/year while the incidence in children is reportably higher at 0.08 cases per 100,000 people/year.[4]  Necrotizing Fasciitis is considered a rare condition, however, the mortality rate remains high. Evidence has estimated the mortality rate to be at 20-40%.[5]  According to the Center for Disease Control there is an estimated 9,000-11,500 cases of necrotizing fasciitis occur each year in the United States, with a resultant 1,000-1,800 deaths annually.

Characteristics/Clinical Presentation

The patient may initially present with increasing pain, tenderness to palpation to the local area and periwound, erythema, swelling, crepitus, purulent drainage and usually a history of some type of trauma. Complaints of flu-like symptoms (nausea, vomiting, fever, malaise etc.) are also common. Patients can present with symptoms of sepsis that include fever, tachycardia, altered mental state and diabetic ketoacidosis that typically accompanies trauma to the skin.[3]

Clinical presentation of necrotizing fasciitis varies and can typically be mistaken for other pathologies, such as cellulitis and superficial skin infections. Awareness of the presentation of necrotizing fasciitis clinically is critical due to the rapid progression of the disease. Evidence has shown that accurate diagnosis is difficult with only 15% to 34% of patients with necrotizing fasciitis having the appropriate admitting diagnosis.[3] Misdiagnosis often occurs due to the vague symptoms that may be present (i.e erythema, fever, pain) or the lack thereof. 

                                                                             Initial Appearance

Courtesy of University of Louisville Hospital
Courtesy of University of Louisville Hospital

Associated Co-morbidities

Studies have shown that there are certain factors that can predispose patients to contract an infection. A recent study found that 70.3% of patients diagnosed with NF had diabetes mellitus. [6]


Risk factors for necrotizing fasciitis:[3]
• Diabetes
• Chronic disease
• Immunosuppresion
• Intravenous drug use
• Peripheral vascular disease
• Renal failure
• Underlying malignancy

Typically necrotizing fasciitis occurs following some type of trauma to the skin, however, non-traumatic causes have also been reported. The causative factor may be as trivial as a scratch or insect bite.[3]  There have also been reported cases of necrotizing fasciitis occurring following acupuncture treatment and joint aspirations. 

Medications

Necrotizing fasciitis is treated with antibiotics usually administered intravenously, however, until surgical debridement has occurred tissue hypoxia limits the efficacy of intravenous antibiotics.[3]  A high dose antibiotic regimen is critical in the treament of the infection in order to limit the amount of tissue damage that may occur.  Also, the inflammation that is associated with the infection causes intense pain and discomfort that is unrelieved by analgesic medications.[7]  These two clinical findings present in necrotizing fasciitis assist to differentiate it from cellulitis.

Diagnostic Tests/Lab Tests/Lab Values

Diagnostic tests vary from each facility but the most common imaging includes computed tomography (CT), ultrasound (US), and magnetic resonance imaging (MRI).  On the CT, deep fascial thickening, enhancement, fluid and gas in the soft tissue planes in and around superficial fascia are indicators of NF.  For a positive finding using US, thickening and distortion of deep fascia, and fluid collections along deep fascia are denoted.  MRI indicators include deep fascial thickening, deep fascial fluid collections, and hyperintense T2W signal within muscles.  MRI becomes controversial because some authors state that fascial enhancement is an indicator, while other authors state that lack of fascial enhancement is a positive finding. 

Laboratory tests utilized for necrotizing fasciitis are the same as ones used for severe soft tissue infections which include:
• Complete blood count
• Electrolytes
• Erythrocyte sedimentation rate
• C-reactive protein

A numerical score sheet, called the laboratory risk indicator for necrotizing fasciitis (LRINEC), was devised from lab parameters as a possible indicating tool for detection of necrotizing fasciitis. Score of ≥6 has a positive predictive value of 92% and a negative predictive value of 96%. [6]


In addition, blood and pus cultures could be examined and surgical exploration may be indicated to confirm the diagnosis of NF.[8]

Etiology/Causes

Necrotizing Fasciitis is caused from bacteria.  The most common bacteria associated with NF after minor trauma is Group A Strep.  When NF is developed after surgery, it is likely a mix of bacteria.  Once entering the body, it rapidly reproduces and emits toxins/enzymes that damage fascia and soft tissue.  The bacteria will shield itself from the body's immune system which speeds up the proliferation along tissue planes.[9]

Any condition that disrupts the skin's characteristics can result in infection.  Some of these conditions include skin trauma, infected needle (i.e. IV drug abusers), psoriasis, bed sores, chicken pox, and bug bites.[8]

Systemic Involvement

There are multiple systems that are compromised because of necrotizing fasciitis.  If untreated, NF can lead to multi-system organ failure.  Specific systems involved include:  integumentary, cardiovascular, pulmonary, gastrointestinal, genitourinary, and immunologic.  The integumentary system is involved because of the tissue decay spawned from the infection.  The cardiovascular system is implicated from the hypotension that occurs as a sign of NF.  In addition, heart failure can result from advancement of the condition.  The pulmonary system can be compromised from eventual respiratory failure that can occur in later stages.  Common signs of NF is nausea and vomiting, which affects the gastrointestinal system.  Renal failure can also develop which connects the genitourinary system involvement.  With fever being a common sign, the immunological system becomes affected as well.[10]

Medical Management (current best evidence)

An aggressive form of treatment for Necrotizing Fasciitis is necessary due to the rapid progression of the infection once contracted. The typical management includes intravenous broad-spectrum antibiotics and early surgical debridement in order to remove the necrotic tissue.[3]  Early recognition is vital for successful treatment. If detected during the early stages, surgical debridement can be minor and more localized to the infected epidermis, subcutaneous and adipose tissue. 

In the later stages of necrotizing fasciitis, systemic shock can occur resulting in failure of many organ systems. Respiratory failure, heart failure, low blood pressure and renal failure may occur in this stage. Limb amputation is necessary once the infection begins to spread to other organ systems.

Hyperbaric oxygen therapy has been proposed as an adjunct therapy for the treatment of necrotizing fasciitis. However, evidence has found conflicting results on the efficacy of this treatment.  In a recent systemic review, the main advantages of hyperbaric oxygen therapy in addition to standard regimes are tissue preservation and decreased mortality.[5]  However, in another study, Golger et al found that the addition of hyperbairc oxygen therapy showed no improvement in mortality rate.[11]  A need exists for higher levels of research to be conducted for more conclusive results.

                                                              Following initial Surgical Debridement

Courtesy of University of Louisville Hospital
Courtesy of University of Louisville Hospital

                                                                      After Surgical Debridement 

Courtesy of University of Louisville Hospital
Courtesy of University of Louisville Hospital

Physical Therapy Management (current best evidence)

Physical therapy management will primarily occur after surgical debridement.  The PT may utilize negative pressure wound therapy (NPWT) to enhance blood perfusion and promote granulation tissue, especially in the depth of the wound.  In addition, NPWT can remove exudate, which decreases the inhibitory mediators and matrix metalloproteinases that interfere with the healing process.[12]  At times, pulse lavage with suction could be utilized for debridement.  In addition, non-contact, low frequency ultrasound can be used for debridement facilitation.  After the wound has healed, scar management is important in preventing adhesions.  Range of motion, mobility, and exercise is crucial in the prevention of contractures.[13]

                                                                 Negative Pressure Wound Therapy

Courtesy of University of Louisville Hospital
Courtesy of University of Louisville Hospital

Alternative/Holistic Management (current best evidence)

The treatment of necrotizing fasciitis strongly emphasizes immediate medical management.  Alternative management does not appear to be an option as it lacks evidence.

Differential Diagnosis

Certain conditions need to be considered during the diagnosis process for necrotizing fasciitis.  Those conditions include:[14]

• Cellulitis
• Acute Epididymitis
• Gas Gangrene
• Hernias
• Orchitis
• Testicular Torsion
• Toxic Shock Syndrome

Case Reports/ Case Studies

Groth D, Henderson SO. Necrotizing Fasciitis Due to Appendicitis. Am J Emerg Med 1999; 17: 594- 596.

Hefny AF, Abu-­Zidan FM. Necrotizing fasciitis as an early manifestation of tuberculosis: report of two cases. Turkish Journal of Trauma & Emergency Surgery 2010;16 (2):174-176.

Resources

The National Necrotizing Fasciitis Foundation. Available online at http://www.nnff.org/

PubMed Health. Available online at www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002415/

Recent Related Research (from Pubmed)

Search Terms:  Necrotizing Fasciitis

Recent Related Research (from Pubmed)

Search Terms:  Necrotizing Fasciitis and Treatment

References

see adding references tutorial.

  1. Shupak A, Shoshani O, Goldenberg I, Barzilai A, Moskuna R, Bursztein S. Necrotizing fasciitis: An indication for hyperbaric oxygenation therapy? Surg. 1995 November; 118 (5): 873-78.
  2. Hsiao C-T, Weng H-H, Yuan Y-D, Chen C-T, Chen I-C. Predictors of mortality in patients with necrotizing fasciitis. American Journal of Emergency Medicine. 2008 April 19; 26: 170–75
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Puvanendran R, Huey J, Pasupathy S. Necrotizing fasciitis. Can Fam Physician 2009 October; 55 (10): 981-7
  4. File Jr TM, Tan JS, DiPersio JR. Group A streptococcal necrotizing fasciitis. Diagnosing and treating the “flesh-eating bacteria syndrome”. Cleve Clin J Med 1998; 65(5):241-9.
  5. 5.0 5.1 Jallali N. et al. Hyperbaric oxygen as adjuvant therapy in the management of necrotizing fasciitis. The American Journal of Surgery 2005; 198:462–466
  6. 6.0 6.1 Wong CH, Chang HC, Pasupathy S, Khin LW, Tan JL, Low CO. Necrotizing fasciitis: clinical presentation, microbiology, and determinants of mortality. J Bone Joint Surgery Am 2003;85-A(8):1454-60.
  7. Bisno AL, Cockerill FR, Bermudez CT. The Initial Outpatient-Physician Encounter in Group A Streptococcal Necrotizing Fasciitis. Clinical Infectious Diseases. 2000 Aug; 31:607–8.
  8. 8.0 8.1 Fazeli M, Keramati M. Necrotizing fascitis: an epidemiologic study of 102 cases. Indian Journal Of Surgery 2007;69:136-139.
  9. The National Necrotizing Fasciitis Foundation. What is NF? www.nnff.org/nnff_what.htm (accessed 1 Apr 2012).
  10. Goodman C, Snyder T. Differential Diagnosis for Physical Therapists Screening for Referral. 4th ed. St. Louis: Saunders Elsevier, 2007.
  11. Golger A, Ching S, Goldsmith CH, Pennie RA, Bain JR. Mortality in patients with necrotizing fasciitis. Plast Reconstr Surg 2007; 119(6): 1803-7.
  12. Baharestani M. Negative pressure wound therapy in the adjunctive management of necrotizing fascitis: examining clinical outcomes. Ostomy Wound Management 2008;54:44-50.
  13. Broers, M. Necrotizing Fasciitis at University Hospital [online]. E-mail to Sara Halliday (shalliday01@bellarmine.edu) 2012 Apr 1 [cited 2012 Apr 4].
  14. Medscape Reference. Necrotizing Fasciitis Differential Diagnosis. http://emedicine.medscape.com/article/2051157-differential (accessed 1 Apr 2012).

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