Triple therapy is recommended: penicillin or ampicillin for Clostridia, Streptococci, and Peptostreptococcus; clindamycin or metronidazole for anaerobes, Bacteroides fragilis, Fusobacterium, and Peptostreptococcus; and gentamicin or another aminoglycoside for Enterobacteriaceae. Imipenem or meropenem can be used as the initial agent for high beta-lactamase resistance, wide-spectrum efficacy, and inhibition of endotoxin release from aerobic bacilli. Tetanus prophylaxis with absorbed tetanus toxoid and passive immune coverage with tetanus hyperimmune globulin is indicated for a patient whose history of immunization is unclear or unavailable.6
Surgery
Urgent surgical consultation is necessary. Early recognition and prompt aggressive debridement of all necrotic tissue is critical for survival—in fact, it is the only therapy demonstrated to improve the rate of survival.7 Necrotic tissue serves as a culture medium and creates an anaerobic environment, which hinders an adequate immune response. Sufficient debridement consists of exposure to all margins of viable tissue. Antibiotics are important but are secondary to urgent removal of the toxic tissue.
Hyperbaric oxygen therapy
All necrotizing infections are associated with ischemia, reduced tissue oxygen tension, and a decrease in host cellular immunity. The physciological rationale for increasing oxygen is that tension ischemia may be reversed and host defense mechanisms improved. Hyperbaric oxygen is generally considered an important adjunct in the treatment of clostridial myonecrosis or gas gangrene.
Studies have failed to show statistically significant outcome differences with respect to mortality and length of hospitalization.3 Some studies show improvement of survival rates or limb salvage; others show no difference in outcomes with hyperbaric oxygen. Note that these studies show no consistency in patient population or number of visits to the operating room. More evidence is needed, preferably by way of randomized controlled trials, before routine or wide-spread use of hyperbaric oxygen can be recommended.
The patient’s treatment and outcome
The emergency department physicians initiated intravenous antibiotics and obtained an urgent surgical consultation. In addition, they sent for blood cultures and other laboratory tests.
In the operating room, surgeons debrided her skin and removed all necrotic muscles and skin in her perineum and entire medial thigh during the first surgery. Eighteen hours later she returned to the operating room—the infection had spread to once-viable tissue from the symphysis pubis to the knee. The family was consulted concerning a more radical surgical approach, a hip disarticulation or hemipelvectomy. They declined. The patient was made comfortable; she died 12 hours later. Her wound culture later grew E coli, Proteus vulgaris, Coryne-bacterium, Enterococcus, Staphylococcus spp, and Peptostreptococcus.
CORRESPONDENCE
Susan Dufel, MD, Department Trauma and Emergency Medicine, University of Connecticut, 80 Seymour Street, Hartford CT 06102. E-mail: sdufel@harthosp.org