Necrotizing Fasciitis

During this ambulatory internal medicine selective, I have had the opportunity to assess several patients referred to our clinic for possible cellulitis.Skin and soft tissue infections are common but recognizing the dangerous ones that need prompt admission and treatment from those that can be treated with oral antibiotics as an outpatient is crucial. One of the most notorious soft tissue infections is necrotizing fasciitis, an infection that spreads quickly along fascial layers and can lead to the development of toxic shock syndrome resulting in organ failure and death. There are two clinical types of necrotizing fasciitis, Type I which is a polymicrobial infection with anaerobes (bacteroides, peptostreptococcus) and a facultative anaerobe (enterobacterales or non group A streptococcus) and Type II which is a monomicrobial infection with streptococcus pyogenes (group A strep). 

 

Signs & Symptoms: Signs and symptoms of necrotizing fasciitis typically develop acutely (over the course of hours).

 

Early signs and symptoms:

• Red, warm, swollen area of skin, not well demarcated that spread quickly (mark the area of erythema)
• Severe pain or edema beyond the area of redness
• Fever

Late symptoms:

• Ulcers, blisters, black areas or skin colour changes
• Crepitus of the skin
• Oozing/pus
• Dizziness
• Fatigue
• Nausea
• Diarrhea
• Tachycardia, tachypnea, hypotension

Common Findings on Bloodwork/Imaging:

• WBC: abnormally high or low WBC
• Sodium: may be decreased
• Urea/Creatinine: may be elevated
• CRP: usually elevated
• CK: may be elevated
• Lactate: usually elevated
• Blood and Tissue Cultures: positive (polymicrobial or monomicrobial)
• Arterial Blood Gas: hypoxemia, acidosis
• Radiography: edema extending along fascial planes/soft tissue gas

Management of Necrotizing Fasciitis

The key principles in the management of necrotizing fasciitis are surgical debridement and empiric antibiotics. Delaying surgical debridement by >12 hours has been shown to be associated with an increased need for future debridement, organ failure and higher rates of mortality. Empiric antimicrobial therapy should be started immediately, as well as fluids for hemodynamic support. Recommended empiric regimens include:

• Vancomycin, linezolid, tedizolid or daptomycin and 
• Piperacillin/tazobactam or a carbapenem and
• Clindamycin (for the antitoxin effects)

 

References:

1. Necrotising Fasciitis. BMJ Best Practice. https://bestpractice-bmj-com.myaccess.library.utoronto.ca/topics/en-gb/821/history-exam
2. Necrotizing Soft Tissue Infections. UpToDate. https://www.uptodate.com/contents/necrotizing-soft-tissue-infections?search=necrotizing%20fasciitis&source=search_result&selectedTitle=1~135&usage_type=default&display_rank=1
3. Necrotizing Fasciitis. Centers for Disease Control and Prevention. https://www.cdc.gov/groupastrep/diseases-public/necrotizing-fasciitis.html