In most cases, necrotizing fasciitis can be diagnosed on clinical suspicion based on physical exam findings such as crepitus, edema extending beyond the area of erythema, and extreme pain or anasthesia in late-presenters. Technically, suspicion of necrotizing fasciitis is only officially confirmed when infected and devitalized tissue is visualized during surgical debridement.
In cases where there may be some doubt as to the presence of necrotizing fasciitis, gas being present in soft tissues on CT can help confirm your suspicion. This is most commonly seen in polymicrobial or clostridial necrotizing fasciitis, and is a highly specific finding that should prompt immediate surgical debridement.
Necrotizing fasciitis is a surgical emergency and requires immediate surgical debridement in order to excise all devitalized and infected tissue to prevent further spread. Continual debridement and re-examination in the OR should be done every 1-2 days until necrotic tissue is no longer visualized.
Patients with necrotizing fasciitis will likely require aggressive resuscitation with IV fluids and pressors, as they will frequently present in septic shock.
In cases of necrotizing fasciitis complicated by toxic shock syndrome thought or confirmed to be due to group A streptococcus (Streptococcus pyogenes), treatment with IV immune globulin (IVIG) in combination with antibiotics has been shown to reduce mortality compared to treatment with antibiotics alone. This likely results from decreased circulating toxin as a result of IVIG administration.
The antibiotic regimen for patients with necrotizing fasciitis should include a carbapenem (such as meropenem or ertapenem) or alternatively piperacillin-tazobactam. This allows for coverage of gram positives, gram negatives, and anaerobes.
Clindamycin is also typically included in the antibiotic regimen for treatment of necrotizing fasciitis. Clindamycin is especially useful due to its ability to halt toxin production, as its mechanism involves inhibition of bacterial ribosomes needed for protein production.
An antibiotic regimen for treatment of necrotizing fasciitis should also cover for MRSA. Antibiotics such as vancomycin or daptomycin are reasonable choices to this end.
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