Necrotizing Fasciitis
Key Points
Necrotizing fasciitis is an uncommon soft-tissue infection characterized by extensive suppurative fasciitis, vascular thrombosis, and cutaneous gangrene
The infection progresses rapidly over hours to several days, spreading along superficial and deep fascial tissue planes to involve subcutaneous tissue and fascia, with secondary necrosis of the overlying skin
Patients often suffer from diabetes mellitus, alcoholism, collagen vascular disease, or conditions requiring immunosuppression
Type I necrotizing fasciitis usually occurs after trauma or surgery caused by polymicrobial anaerobic and facultative bacteria
Type II necrotizing fasciitis is a monomicrobial infection usually with virulent subtypes of Streptococcus pyogenes
Patients are usually febrile and present with extensive, rapidly progressive eyelid swelling, and erythema, pain, crepitus, a foul-smelling watery wound discharge, and areas of necrosis
Treatment includes broad-spectrum antibiotics, surgical debridement, fluid resuscitation, and cardiorespiratory supportive care when necessary to maintain vital organ function
Systemic complications are frequent and the prognosis generally is poor with a mortality rate up to 50%
The first description of necrotizing fasciitis (NF) is generally attributed to Fournier in 1883,1 although a very similar gangrene-like infectious process was previously described by Ambrose Paré in 1575.2 However,
the term, NF, was only introduced by Wilson in 1952.3 NF is an uncommon soft-tissue infection characterized by extensive suppurative fasciitis, vascular thrombosis, and cutaneous gangrene.4,5 The infection progresses rapidly over hours to several days, spreading along superficial and deep fascial tissue planes to involve subcutaneous tissue and fascia, with secondary necrosis of the overlying skin.5,6 The most common causative organism is group A β-hemolytic Streptococcus, but other gram-positive, gram-negative, and anaerobic bacteria, and even fungi, can also be involved.7,8 NF commonly occurs on the extremities, abdomen, and perineum, and less commonly in the head and neck.
NF only occasionally involves the eyelids, with about 150 cases reported.7,9,10,11,12 Patients often suffer from diabetes mellitus, alcoholism, collagen vascular disease, or conditions requiring immunosuppression,13,14,15 although in many cases, there are no obvious predisposing risk factors for infection. Periorbital NF has been reported after trauma,16,17 after surgery including dacryocystorhinostomy,18 and blepharoplasty,19 and following an insect bite.9
Eyelid NF can be caused by aerobic, anaerobic, or polymicrobial infections, although the vast majority of bacterial isolates are group A β-hemolytic streptococci or Staphylococcus aureus.10,20,21 In a report of 67 cases of NF at a Philippine University Medical Center, Escherichia coli was the most common isolate seen in 44% of patients.22 A case of NF caused by Apophysomyces belonging to the order Mucorales was reported in a burn patient.23
Etiology and Pathogenesis
Necrotizing soft-tissue infections are potentially lethal infections that require early recognition and aggressive management.24,25,26 These infections most frequently involve the abdomen, perineum, and lower extremities, but can occur in any part of the body. Surgery and trauma are the most common predisposing factors, but it rarely has been reported following diverse etiologies such as spinal anesthesia,27 measles vaccine,28 as a complication of infectious mononucleosis,29 following dental procedures,30 and associated with insect bites.31 Immunocompromised individuals, especially those with diabetes, are more likely to develop necrotizing infections. However, in many cases, there is no identifiable preceding event.
All necrotizing infections are best viewed as a spectrum of clinical conditions with similar pathophysiological features and common treatment approaches.26,32,33 NF has been classified according to the types of microbial organisms involved. Type I NF usually occurs after trauma or surgery.3,34 Initially, the subcutaneous fat and fascia are primarily involved, and later may extend into the muscle. But most commonly, widespread necrosis is present in the subcutaneous fat and fascia, with relative sparing of muscle. Polymicrobial anaerobic and facultative bacteria are involved in tissue destruction, and gas may or may not be present. The clinical pace of the disease is usually slower than that seen with type II NF.8 Patients usually have a predisposing risk factor, such as diabetes mellitus.
Type II NF is a monomicrobial infection usually with virulent subtypes of Streptococcus pyogenes.5,35,36 It presents clinically in a similar fashion to type I NF, but the presence of gas in tissues is unusual.8 Varicella infection and the use
of nonsteroidal anti-inflammatory drugs may be additional predisposing risk factors besides trauma or surgery.5,37,38,39 This form of NF is also more frequently associated with streptococcal toxic shock syndrome.40
of nonsteroidal anti-inflammatory drugs may be additional predisposing risk factors besides trauma or surgery.5,37,38,39 This form of NF is also more frequently associated with streptococcal toxic shock syndrome.40
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