Necrotizing Fasciitis

Educational Objectives

The goal of this program is to improve the diagnosis and management of necrotizing infections. After hearing and assimilating this program, the clinician will be better able to:

1. Differentiate among the various types of necrotizing infections.
2. Explain the benefit of the drop or finger test in diagnosis of necrotizing infections.

Summary

Necrotizing fasciitis: diagnosed clinically and primarily treated surgically; there have been no significant changes in the approach to this disease over several decades; these infections are classified as necrotizing and nonnecrotizing infections; necrotizing infections have multiple different names; currently, all the names of necrotizing soft tissue infections are used synonymously; originally, there was a difference between necrotizing fasciitis, Fournier gangrene, necrotizing myositis, and Meleneys gangrene; treatment is identical for all necrotizing infections; in general, these are very rare but life-threatening; they affect skin, subcutaneous fat, small blood vessels, fascia, and potentially the muscles; cause massive tissue destruction and tissue death; morbidity and mortality are high if not treated quickly

Susceptible patients: any individual is vulnerable with the correct port of entry and the right bacteria; if group A streptococcus or Vibrio have access beneath the skin, they can be difficult to treat and can progress very rapidly; most patients have some type of medical comorbidity that affects their immune systems and predisposes them to these infections

Classification of necrotizing infections: type I — the most common and is a polymicrobial infection; a typical sacral decubitus ulcer that extends and becomes a necrotizing soft tissue infection; usually infected with resident microbiota; type II — usually monomicrobial; the causative organism is usually group A streptococcus; these infections progress very rapidly; type III — involves only gram-negative organisms; the causative organism is usually vibrio; usually associated with history of water exposure; type IV — invasive fungal infection that is usually trauma associated; multiple debridements and high-dose antibiotics required

Spread of necrotizing infections: the fundamental principle underlying the spread of these infections includes access of bacteria to a place that is not usually accessible to bacteria, resulting in local inflammation that affects local blood vessels, causing microthrombosis; microthrombosis progresses to cause local ischemia or necrosis, setting up an ideal environment for bacterial proliferation; bacteria then spread; the cycle is then repeated, and the infection continues to spread until treated; these infections can occur anywhere in the body

Diagnosis: radiography assists in determining presence or absence of subcutaneous air; overall, these are late findings with poor sensitivity; computed tomography can show the extent of the disease; clinicians should not delay surgical debridement for imaging; magnetic resonance imaging is theoretically a gold standard for diagnosing necrotizing fasciitis or soft tissue infection; laboratory risk indicator for necrotizing fasciitis (LRINEC) score, published by Wong et al (2004), involves a scale comprising multiple laboratory test values including C-reactive protein, total white blood cell count, hemoglobin, sodium, creatinine, and glucose; score of <5 indicates <50% risk of necrotizing soft tissue infection; score of ≥ 8 indicates risk of ≥ 75%; addition of serum lactate levels to the LRINEC scale was an independent predictor for mortality and indicates the need for immediate surgery; if there is diagnostic doubt, consider surgery; a drop or finger test is simple and can be done at the bedside; clinicians dissect the suspected site for infection to the level of fascia under the effect of local anesthesia; put the gloved finger on the tissues; easy separation of the tissue is suggestive of dead tissue; it is important to determine if the infection is necrotizing or nonnecrotizing, which can be difficult

Antimicrobial therapy: treatment should be initiated with broad-spectrum antibiotics as >70% of these infections are polymicrobial; surgery should yield plenty of tissue for culture to narrow the coverage; choice of antimicrobial also depends upon any concomitant organ failure; duration of therapy depends on the predominant organism; bacterial infections require 10 to 14 days of therapy; fungal infections may require longer

Readings

Livshits D, Sokup B, Farrell R, et al. Finger test for the diagnosis of a critically ill patient with necrotizing fasciitis. J Emerg Med. 2022;63(1):102-105. doi:10.1016/j.jemermed.2022.04.004; Puvanendran R, Huey JC, Pasupathy S. Necrotizing fasciitis. Can Fam Physician. 2009;55(10):981-987; Yaghoubian A, de Virgilio C, Dauphine C, et al. Use of admission serum lactate and sodium levels to predict mortality in necrotizing soft-tissue infections. Arch Surg. 2007;142(9):840–846. doi:10.1001/archsurg.142.9.840.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Kryzaniak was recorded at the 2023 San Diego Day of Trauma, held November 3, 2023, in San Diego, CA, and presented by Scripps Health. For information on future CME activities from this presenter, please visit https://www.scripps.org/. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.50 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.50 CE contact hours.

Lecture ID:

EM411201

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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