Necrotizing fasciitis

Necrotizing fasciitis is a life-threatening subcutaneous soft-tissue infection that requires a high index of suspicion for diagnosis.

Infection may be polymicrobial in etiology (type I) due to mixed anaerobic/facultative anaerobic organisms, or due to a single organism (type II), most commonly Streptococcus pyogenes, also called group A streptococcus.

Necrotizing fasciitis should be suspected in any patient with a rapidly progressing soft-tissue infection and any of the following: severe pain (disproportionate to the clinical findings) or anesthesia over the site of infection; edema and erythema (edema will typically extend beyond the erythema); systemic signs of infection. However, necrotizing fasciitis can be easily missed because the patient may present earlier in the disease process with nonspecific signs and symptoms.

No laboratory or imaging studies, alone or in combination, are sufficiently sensitive and specific to definitively diagnose or rule out necrotizing fasciitis.

An urgent surgical consult should be obtained as soon as the diagnosis is suspected. Treatment should not be delayed while awaiting microbiologic and imaging investigations.

Definitive treatment is surgical debridement, repeated as necessary. Antibiotic therapy is crucial, but is considered adjunctive to surgical management. Empiric antibiotics should cover major bacterial etiologic agents, and group A streptococcal toxin production that can accompany type II necrotizing fasciitis.

Necrotizing fasciitis is a life-threatening subcutaneous soft-tissue infection progressively extending to the deep soft tissues including muscle fascia and overlying fat, but not into the underlying muscle. The causal organisms may be aerobic, anaerobic, or mixed flora. Two main clinical forms exist. Type I necrotizing fasciitis is a polymicrobial infection with an anaerobe such as Bacteroides, Peptostreptococcus, or Clostridium and facultative anaerobes such as certain Enterobacterales or non-group A streptococcus.[1]Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. Philadelphia, PA: Elsevier; 2015:1194-215.[2]Sartelli M, Guirao X, Hardcastle TC, et al. 2018 WSES/SIS-E consensus conference: recommendations for the management of skin and soft-tissue infections. World J Emerg Surg. 2018 Dec 14;13:58. https://wjes.biomedcentral.com/articles/10.1186/s13017-018-0219-9 http://www.ncbi.nlm.nih.gov/pubmed/30564282?tool=bestpractice.com [3]Sartelli M, Coccolini F, Kluger Y, et al. WSES/GAIS/WSIS/SIS-E/AAST global clinical pathways for patients with skin and soft tissue infections. World J Emerg Surg. 2022 Jan 15;17(1):3. https://wjes.biomedcentral.com/articles/10.1186/s13017-022-00406-2 http://www.ncbi.nlm.nih.gov/pubmed/35033131?tool=bestpractice.com [4]Diab J, Bannan A, Pollitt T. Necrotising fasciitis. BMJ. 2020 Apr 27;369:m1428.[5]Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014 Jul 15;59(2):e10-52. https://academic.oup.com/cid/article/59/2/e10/2895845 http://www.ncbi.nlm.nih.gov/pubmed/24973422?tool=bestpractice.com Type II necrotizing fasciitis is most commonly a monomicrobial infection with typically Streptococcus pyogenes (group A streptococci) or occasionally Staphylococcus aureus.[1]Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. Philadelphia, PA: Elsevier; 2015:1194-215.[2]Sartelli M, Guirao X, Hardcastle TC, et al. 2018 WSES/SIS-E consensus conference: recommendations for the management of skin and soft-tissue infections. World J Emerg Surg. 2018 Dec 14;13:58. https://wjes.biomedcentral.com/articles/10.1186/s13017-018-0219-9 http://www.ncbi.nlm.nih.gov/pubmed/30564282?tool=bestpractice.com [3]Sartelli M, Coccolini F, Kluger Y, et al. WSES/GAIS/WSIS/SIS-E/AAST global clinical pathways for patients with skin and soft tissue infections. World J Emerg Surg. 2022 Jan 15;17(1):3. https://wjes.biomedcentral.com/articles/10.1186/s13017-022-00406-2 http://www.ncbi.nlm.nih.gov/pubmed/35033131?tool=bestpractice.com [4]Diab J, Bannan A, Pollitt T. Necrotising fasciitis. BMJ. 2020 Apr 27;369:m1428.

Other infectious etiologies may rarely cause a monomicrobial necrotizing infection that may be associated with specific exposures or risk factors (e.g., freshwater exposure associated with Aeromonas hydrophila, saltwater exposure or consumption of raw oysters associated with Vibrio vulnificus, recent travel to [or living in] Taiwan, where Klebsiella pneumoniae is a common cause of monomicrobial infection).[6]Cheng NC, Yu YC, Tai HC, et al. Recent trend of necrotizing fasciitis in Taiwan: focus on monomicrobial Klebsiella pneumoniae necrotizing fasciitis. Clin Infect Dis. 2012 Oct;55(7):930-9. https://academic.oup.com/cid/article/55/7/930/427026 http://www.ncbi.nlm.nih.gov/pubmed/22715175?tool=bestpractice.com