Necrotizing soft tissue infection: Difference between revisions
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*See Classification, below |
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| − | *Most commonly caused by monomicrobial [[Streptococcus pyogenes]], [[Staphylococcus aureus]], [[Clostridium |
+ | *Most commonly caused by monomicrobial [[Streptococcus pyogenes]], [[Staphylococcus aureus]], [[Clostridium]], or [[Vibrio]], or polymicrobial infections that include Gram-positives, Gram-negatives, and anaerobes |
===Classification=== |
===Classification=== |
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Revision as of 15:25, 28 January 2022
Background
Microbiology
- See Classification, below
- Most commonly caused by monomicrobial Streptococcus pyogenes, Staphylococcus aureus, Clostridium, or Vibrio, or polymicrobial infections that include Gram-positives, Gram-negatives, and anaerobes
Classification
- Although it is classically divided into Type 1 (polymicrobial) and Type 2 (monomicrobial), others have proposed an extension to include Type 3 (water-associated monomicrobial) and Type 4 (fungal).
- Type 1: polymicrobial, including Staphylococcus aureus, Gram-negative bacilli, and anaerobes
- Type 2: monomicrobial Gram-positive infections, primarily Streptococcus pyogenes (most common) but also Staphylococcus aureus or Clostridium (penetrating trauma, soil exposure)
- Type 3: monomicrobial Gram-negative infections, generally caused by water-associated Vibrio vulnificus or Aeromonas hydrophila
- Type 4: fungal, caused by Candida species, and exceedingly rare
Management
- Surgical debridement!
- Empiric antibiotics
- Piperacillin-tazobactam 4.5 g IV q8h (or, alternatively, meropenem)
- Clindamycin 600 to 900 mg IV q8h, for synergy and the Eagle phenomenon and decreased toxin production
- If risk for MRSA, add vancomycin 15-20 mg/kg IV q8-12h
- If water exposure, add two of: a fluoroquinolone, a carbapenem, a third-generation cephalosporin, and/or doxycycline (should have double-coverage pending susceptibilities)
- Then narrow based on the Gram stain an culture
- Can consider IVIg, rarely, in toxic shock syndrome
Eagle Effect
- Originally, referred to decreased effectiveness of penicillins at high concentrations
- Now, refers to decreased effectiveness of penicillins at high bacterial burden (when in stationary phase)
- Clindamycin kills enough of the bacteria that are in stationary phase that the bacteria return to logarithmic growth phase, where penicillins are more effective
Further Reading
- RCT of IVIG: Madsen MB et al. Immunoglobulin G for patients with necrotising soft tissue infection (INSTINCT): a randomised, blinded, placebo-controlled trial. Intensive Care Med. 2017;43:1585-93.
