Rationale:

• Surgical debridement of nonviable tissue is necessary to remove nutrients for continued bacterial growth, which contribute to both metabolic abnormalities and development of a compartment syndrome.
• Remediation of vascular supply improves delivery of oxygen and antimicrobials to the site of infection.
• The recommended antimicrobial regimens are based on the types of microorganisms most frequently associated with these infections and their usual sensitivities.
• It is crucial to consider factors that increase the likelihood of resistance, such as recent hospitalization, recent antimicrobial usage, or previous infection with a resistant organism.
• Large numbers of streptococci are present in tissues exhibiting necrotizing fasciitis and are mostly in stationary phase. Critical penicillin-binding proteins are not expressed, making penicillin treatment ineffective in animal models.
• Although penicillin has good antimicrobial activity against Clostridium species, it is less efficacious in experimental models of infection.
• Treatment with a protein-synthesis inhibitor such as clindamycin suppresses bacterial toxin production, an important advantage in infections caused by potent toxin-producing organisms.

Evidence:

• Deep-seated infection of the fascia and muscle requires urgent surgical debridement and must not be treated with antibiotics alone (101; 18).
• A delay in surgical debridement increases mortality (102).
• Multiple debridements are often required for patients with necrotizing fasciitis or myonecrosis (18).
• Severe group A streptococcal infections should be treated with clindamycin because experimental data (103) and clinical studies have reported failures with penicillin and better efficacy with clindamycin (104; 105).
• In experimental animal studies, penicillin given 2 hours after soft tissue injection of group A streptococcus resutled in survival that was no better than untreated control (20% survival). In contrast, animals treated with clindamycin 2 hours, or even 16 hours, after injection of bacteria had survivals of 100% and 70%, respectively (103; 104).
• The superiority of clindamycin to penicillin is due to the ability of clindamycin to inhibit bacterial toxin production and to modulate the host immune response (106). However, because 5% of C. perfringens strains (18) and 5% or more of S. pyogenes strains (107) are clindamycin-resistant, penicillin is added to the regimen until sensitivities are known .
• S. aureus can cause necrotizing fasciitis (41). In these patients, linezolid appears to be the antimicrobial of choice (108).
• The use of hyperbaric oxygen for gas gangrene is controversial as some studies report good results without it (109; 110).
• Studies of the use of intravenous immunoglobulin in necrotizing fasciitis are conflicting (111; 112; 113). At this time there is no official recommendation on its use for streptococcal necrotizing fasciitis (18).

Comments:

• For infections caused by potent toxin-producing gram-positive bacteria, the mechanism of action of the antimicrobial, such as protein synthesis inhibition and, therefore, toxin suppression, may be an important consideration in selecting appropriate antibiotic treatment.
• In 50% of patients with necrotizing fasciitis caused by group A streptococcus, there is no defined portal of entry and the infection begins deep, probably due to hematogenous seeding of an area of minor trauma, such as bruise, torn muscle, sprained ankle, etc. (49; 32). In these cases, severe pain is usually the reason patients seek medical care, and the pain is severe enough that physicians generally prescribe narcotics.
• Fournier's gangrene is a variant of type 1 necrotizing fasciitis that involves the genital area, usually in diabetics. It is caused by mixed flora (gram-positive cocci, gram-negative bacilli, and anaerobes), although it may occasionally be caused by S. aureus alone.
• Traumatic gas gangrene (type 3 necrotizing fasciitis) is usually due to C. perfringens, whereas the spontaneous type is due to C. septicum. The latter is seen most freqently in neutropenic patients and those with a gastrointestinal malignancy. C. sordelli is associated with childbirth or abortion, C. novyi with drug use (114).