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For further information, see CMDT Part 33-31: Anaerobic Infections

Key Features

  • Several terms are used to classify these infections

    • Bacterial synergistic gangrene

    • Synergistic necrotizing cellulitis

    • Necrotizing fasciitis (see Necrotizing Fasciitis)

    • Nonclostridial crepitant cellulitis

  • Usually occur after trauma, ischemia, or surgery

  • Most common in areas contaminated by oral or fecal flora

  • May also be seen in individuals who inject drugs and persons sustaining animal bites

  • All are mixed infections caused by aerobic and anaerobic organisms

  • Although there are some differences in microbiology among these infections, differentiation on clinical grounds alone is difficult

Clinical Findings

  • There may be progressive tissue necrosis, evidence of gas in the tissues (crepitance) and a putrid odor

  • Pain out of proportion to the clinical findings

  • Hemodynamic instability and systemic toxicity may be present


  • Surgical exploration


  • Broad-spectrum antibiotics active against both anaerobes and gram-positive and gram-negative aerobes (eg, intravenous vancomycin plus piperacillin-tazobactam, 4.5 g intravenously every 8 hours) should be instituted empirically and modified by culture results (Tables 30–4 and 30–5)

  • They are given about a week after progressive tissue destruction has been controlled and the margins of the wound remain free of inflammation

  • Aggressive surgical debridement of necrotic tissue is required for cure

Table 30–4.Medication of choice for suspected or documented microbial pathogens (listed in alphabetical order, within classes).

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