EM@3AM: Necrotizing Fasciitis

Author: Jacklyn M. Wagner (Doctor of Physical Therapy, Killeen, TX), Stephanie M. Schenk (Bachelor of Science in Nursing, Killeen, TX), Joshua J. Oliver, MD (EM Attending Physician, San Antonio, TX) // Edited by: Alex Koyfman, MD (@EMHighAK) and Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX) 

Welcome to EM@3AM, an emDocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 50-year-old male with uncontrolled diabetes presents with pain and swelling in his right foot.  He does not recall any injury to the foot or leg.  On exam, crepitus is noted on the foot and ankle.

What is the diagnosis, and what are your next steps?

Answer: Necrotizing fasciitis (NF)

Background:

• NF is a rare but devastating disease involving the skin, soft tissue, and deep fascia that can rapidly progress resulting in loss of limb or loss of life.¹
• The most common risk factor is diabetes mellitus (DM).² Other risk factors include advanced age, cirrhosis, renal failure, cardiovascular disease, obesity, traumatic wounds, and intravenous drug use.^1,3
• NF can affect any part of the body, but it occurs most commonly in the lower extremities.² Fournier’s Gangrene occurs in the setting of perineal involvement.
• There are three categories: type I is polymicrobial, type II is group A streptococcal, type III is clostridial.

Presentation:

• NF presents with vague and non-specific signs and symptoms making it very difficult to diagnose. This is further complicated by patients with DM as they have atypical presentations.  Clinicians must maintain a high level of clinical suspicion of this entity.²
• The most common presenting signs and symptoms are:
  • Pain out of proportion to exam
  • Fever
  • Local swelling
  • Erythema¹
• A history of recent external trauma, including surgery, is often present, but not always.²
• Bullous lesions and crepitus may also be present; however, they tend to be late findings.¹

Evaluation:

• Definitive diagnosis can only be made by direct tissue examination during surgical exploration.⁴ If there is clinical suspicion of NF, an emergent consult should be placed to General Surgery, or the patient should be transferred immediately to a facility with surgical capabilities.
• Obtain CBC, chemistry panel, coagulation panel, lactate, CK.
• A clinical decision making tool exists called the LRINEC score. It can be found at the following link:
  • https://www.mdcalc.com/lrinec-score-necrotizing-soft-tissue-infection
  • When initially derived, it showed promise with a sensitivity and specificity of 90% and 95%, respectively, for LRINEC scores ≥ 6. However, it still missed 10% of patients with NF, who had ≥6 LRINEC scores.⁵
  • On validation, the sensitivity and specificity dropped to 59.2% and 83.8%, respectively.^6,7
• All 6 components of the LRINEC score are based on laboratory results. Waiting for these results and calculating a score before placing an emergent consult to General Surgery would not be in the patient’s best interest.

Management:

• Surgical debridement is the definitive treatment of NF. If patients do not go directly to the OR, they should be admitted to an ICU, as these patients rapidly go into multi organ system failure.
• Resuscitation with IV fluids and vasopressors as needed.
• Broad spectrum antibiotics should be started immediately. A possible regimen includes (one from each category):
  • A Carbapenem or Beta-lactam-beta-lactamase inhibitor
    • Carbapenems include imipenem, meropenem, ertapenem
    • Beta-lactam-beta-lactamase inhibitors include Zosyn, Unasyn, Timentin
    • If allergic, may give an Aminoglycoside or a Fluoroquinolone in addition to Metronidazole
  • Clindamycin
    • Has antitoxin affect for toxic producing strains of both staph and strep species
  • An antibiotic affective against Methicillin-Resistant Staphylococcus Aureus.
    • Examples include Vancomycin, Daptomycin, and Linazolid⁸
  • Hyperbaric oxygen therapy is sometimes discussed as a treatment option, but there is a lack of evidence to support or refute its efficacy for NF.⁹

For more, see this emDocs post.

References:

1. Wang J, Lim H. Necrotizing fasciitis: Eight-year experience and literature review.  Brazilian Journal of Infectious disease. 2014;18(2):137-143.
2. Lacopi E, Coppelli A, Goretti C, Piaggesi A. Necrotizing Fasciitis and the diabetic foot. International Journal of Lower Extremity Wounds. 2015 Dec;14(4):316-27.
3. Shaikh N, El-Menyar A, Mudali IN, Tabeb A, Al-Thani H. Clinical presentations and outcomes of necrotizing fasciitis in males and females over a 12-year period. Annals of Medicine and Surgery. 2015(4):355-360.
4. Machado NO. Necrotizing fasciitis: The importance of early diagnosis, prompt surgical debridement and adjuvant therapy. North American Journal of Medical Science. 2011(3):107-118.
5. Wong CH, Khin LW, Heng KS, Tan KC, Low CO. The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis rom other soft tissue infections. Critical Care Medicine. 2004 Jul;32(7):1535-41
6. Liao C, Lee Y, Su Y, Chuang C, Wong C. Validation of the laboratory risk indicator for necrotizing fasciitis (LRINEC) score for early diagnosis of necrotizing fasciitis. Tzu Chi Medical Journal. 2012 Jun;24(2):73-76.
7. Neeki MM, Dong F, Au C. Evaluating the laboratory risk indicator for differentiating cellulitis from necrotizing fasciitis in the Emergency Department. Western Journal of Emergency Medicine. 2017;18(4):684-689.
8. https://www-uptodate-com.proxy1.athensams.net/contents/necrotizing-soft-tissue-infections?search=necrotizing%20fasciitis%20treatment&sectionRank=1&usage_type=default&anchor=H24&source=machineLearning&selectedTitle=1~112&display_rank=1#H24
9. Levett D, Bennett MH, Millar I. Adjunctive hyperbaric oxygen for necrotizing fasciitis. Cochrane Database Systemic Review. 2015 Jan;(1).