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| ==Background== | | ==Background== |
| * Includes necrotizing forms of cellulitis, myositis, and fasciitis | | *Abbreviation: NSTI |
| * Two types:
| | *Includes necrotizing forms of cellulitis, myositis, and fasciitis |
| ** Type 1: polymicrobial infection
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| ** Type 2: group A strep
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| *** May occur in healthy individuals
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| *** May occur via hematogenous spread from throat to site of blunt trauma
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| ==Necrotizing Fasciitis (NF)==
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| ===Risk Factors===
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| *DM
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| *Drug use
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| *Obesity
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| *Immunosuppression
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| *Recent surgery
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| *Traumatic wounds
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| ===Clinical Features=== | | ===General types=== |
| *Skin exam | | *Type 1: polymicrobial infection |
| **Erythema (without sharp margins) | | *Type 2: [[group A strep]] |
| **Exquisitely tender (pain out of proportion to exam) | | **May occur in healthy individuals |
| **Skip lesions
| | **May occur via hematogenous spread from throat to site of blunt trauma |
| **Hemorrhagic bullae (violaceous bullae)
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| ***May be preceded by skin anesthesia (destruction of superficial nerves)
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| **Crepitus (in type I infections)
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| *Swelling/edema may produce compartment syndrome
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| *Constitutional
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| **Fever
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| **Tachycardia
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| **Systemic toxicity
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| ===Work-Up===
| | {{NSTI types}} |
| *CBC
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| *Chem
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| *PT/PTT/INR
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| *CK
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| *Lactate
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| ===Diagnosis=== | | ==Clinical Features== |
| *Surgical exploration is the ONLY way to definitively establish the diagnosis of necrotizing infection
| | [[File:NectrotizingFasciitis.jpeg|thumb|Nectrotizing fasciitis]] |
| *Imaging
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| **Should not delay surgical exploration
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| **CT is study of choice
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| ====HUCLA NF vs Non-NF Criteria (Wall et al)====
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| *Retrospective study discovered:
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| **WBC count (x10<sup>3</sup>/mm<sup>3</sup>) > 15.4 OR Na (mmol/L) <135
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| **Associated with NF and combo of both increased likelihood of NF
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| **PPV 26%/NPV 99%
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| *Good tool to R/O NF, not a good tool for confirming presence of NF
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| ====Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) Score (Wong et al)====
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| *May use to risk stratify patients p/w signs of cellulitis to determine likelihood of necrotizing fasciitis
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| *Useful in context of a diagnosed or strongly suspected severe soft-tissue infxn
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| *Score based on: '''CRP, WBC, Hb, Na, Cr, Glucose'''
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| *Score > 6 has PPV of 92% and NPV of 96% for necrotizing fasciitis
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| **Be aware LRINEC score has not been prospectively validated, index of suspicion is key
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| #CRP (mg/L) ≥150: 4 pts
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| #WBC count (x10<sup>3</sup>/mm<sup>3</sup>):
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| ##<15: 0 pts
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| ##15-25: 1 pt
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| ##>25: 2 pts
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| #Hb (g/dL):
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| ##>13.5: 0 pts
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| ##11-13.5: 1 pt
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| ##<11: 2 pts
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| #Na (mmol/L) <135: 2 pts
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| #Cr (mg/dL) >1.6: 2 pts
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| #glucose (mg/dL) >180: 1 pt
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| ===Treatment=== | | ==Differential Diagnosis== |
| *Surgical exploration and debridement
| | {{SSTI DDX}} |
| **Indicated in setting of severe pain, toxicity, fever, elevated CK (w/ or w/o radiographic evidence)
| | {{Necrotizing Rashes DDX}} |
| *Abx
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| **Must cover Gram +/- and anaerobes (esp GAS and clostridium)
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| **Piperacillin-tazobactam 3.375-4.5g q6hr AND clindamycin 600-900mg q8hr AND vancomycin 1gm IV q12hr
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| ==Necrotizing Myositis== | | ==Evaluation and Management== |
| ===Background===
| | See specific type: |
| * Much rarer than nec fasc
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| * May be preceded by skin abrasions, blunt trauma, heavy exercise
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| * Most patients are otherwise healthy (DM and other underlying conditions do not appear to increase risk)
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| ===Clinical Features===
| | {{NSTI types}} |
| *Exquisite pain and swelling of affected muscle with induration
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| *Overlying skin changes may manifest later in the course of illness (erythema, warmth, petechiae, bullae)
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| *Hypotension may occur rapidly with development of streptococcal toxic shock syndrome
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| ===Management=== | | ==See Also== |
| * Same as necrotizing fasciitis (see above) | | *[[Necrotizing rashes]] |
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| ==Necrotizing Cellulitis== | | ==External Links== |
| ===Background===
| | *[http://www.mdcalc.com/lrinec-score-for-necrotizing-soft-tissue-infection/ MDCalc - LRINEC Score] |
| *Pts are often much less toxic compared with nec fasc/nec myo | |
| * Two types:
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| **Anaerobic infection (clostridial and nonclostridial)
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| **Meleney's synergistic gangrene
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| ***Rare infection that occurs in postop pts
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| ***Characterized by slowly expanding indolent ulceration that is confined to superficial fascia
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| ***Results from synergistic interaction between S. aureus and microaerophilic streptococci
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| ===Risk Factors=== | | ==References== |
| *Trauma
| | <references/> |
| *Surgical contamination
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| *Spread of infection from bowel to perineum, abdominal wall, or lower extremities
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| ===Clinical Features===
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| *Thin, dark, sometimes foul-smelling wound drainage (often containing fat globules)
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| *Tissue gas formation (crepitus)
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| ===Management===
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| *Same as necrotizing fasciitis (see above)
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| ==Source==
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| * UpToDate
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| [[Category:ID]] | | [[Category:ID]] |
