Necrotizing Skin and Soft-Tissue Infections at a Glance
- Necrotizing skin and soft-tissue infections include necrotizing fasciitis, gangrenous cellulitis, and myonecrosis, and related diseases that cross soft-tissue planes.
- Necrotizing skin and soft tissue infections are locally destructive and frequently have severe systemic complications. They must be recognized rapidly and treated aggressively to minimize mortality.
- Tissue cultures have more utility in necrotizing infections than in simple cellulitis and erysipelas.
- Necrotizing soft-tissue infections require a combination of surgical treatment and antibiotics.
- Radiographic imaging may be helpful in crepitant infections but should not delay surgical therapy in cases where necrotizing infections are suspected.
Necrotizing skin and soft tissue infections (SSTI) include gangrenous cellulitis, necrotizing fasciitis, and anaerobic myonecrosis. All of these conditions are highly destructive locally, and they frequently have severe or lethal systemic complications; they must be recognized early and treated aggressively, usually with a combination of antibiotics, surgical debridement, and supportive measures. However, the infrequency of these infections, coupled with the relatively nonspecific clinical findings early in their course, makes rapid diagnosis difficult; up to 85% of these patients do not have an accurate diagnosis at the time of admission to the hospital.1
Necrotizing fasciitis, especially the monomicrobial form, frequently affects young, healthy patients. However, increased age, immunocompromise including acquired immunodeficiency syndrome (AIDS), chronic illness, alcoholism, and percutaneous drug use are risk factors.2 A chart review from New Zealand found that features common to a high proportion of necrotizing fasciitis patients included diabetes mellitus, gout, congestive heart failure, and recent surgical procedures. However, statistical analysis to assess the validity of these associations was not presented.3 Necrotizing fasciitis arising at sites of recent tattoos4,5 and sclerotherapy has been reported.6 Finally, the role of nonsteroidal anti-inflammatory drugs (NSAIDS) is controversial; many studies have found an association between NSAIDS and necrotizing SSTI, but prospective studies have failed to confirm the speculation that NSAIDS may promote infection progression or delay diagnosis by obscuring early symptoms.7
Clostridial necrotizing SSTI, including anaerobic cellulitis and myonecrosis, arise either from deep traumatic or surgical inoculation, or from hematogenous spread from an internal infectious focus.8 These infections are rare in healthy patients; common associations include malignancy, neutrophil dysfunction, bowel ischemia, and hemolytic-uremic syndrome.9
The most common pathogens mediating necrotizing SSTI are group A β-hemolytic Streptococcus (GAS) in the case of necrotizing fasciitis type II, and anaerobes such as clostridial species in the case of gangrenous cellulitis and myonecrosis. However, other relatively common organisms that cause necrotizing SSTI include Staphylococcus aureus, non-group A streptococcal species, Pseudomonas, Pasteurella, Vibrio, and Enterobacteriaceae (such as Escherichia coli).8,10 These infections are often polymicrobial, with a mix of both pathogens and contaminants (see Table 179-1).
Table 179-1 Etiology of Necrotizing Skin and Soft-Tissue Infections