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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 with no PMH
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| *** May occur via hematogenous spread from throat to site of blunt trauma
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| ==Necrotizing Fasciitis==
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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
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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}} |
| *Labs
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| **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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| *Imaging
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| **CT
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| | ==Clinical Features== |
| | [[File:NectrotizingFasciitis.jpeg|thumb|Nectrotizing fasciitis]] |
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| ===Diagnosis=== | | ==Differential Diagnosis== |
| *Surgical exploration is the only way to definitively establish the diagnosis of necrotizing infection
| | {{SSTI DDX}} |
| *Imaging
| | {{Necrotizing Rashes DDX}} |
| **Should not delay surgical exploration
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| **CT
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| ***
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| ==Necrotizing Myositis== | | ==Evaluation and Management== |
| * Much rarer than nec fasc
| | See specific type: |
| * 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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| ==Necrotizing Cellulitis== | | ==See Also== |
| *Pts are often much less toxic compared with nec fasc/nec myo | | *[[Necrotizing rashes]] |
| * 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=== | | ==External Links== |
| *Trauma
| | *[http://www.mdcalc.com/lrinec-score-for-necrotizing-soft-tissue-infection/ MDCalc - LRINEC Score] |
| *Surgical contamination
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| *Spread of infection from bowel to perineum, abdominal wall, or lower extremities | |
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| ===Clinical Features=== | | ==References== |
| *Thin, dark, sometimes foul-smelling wound drainage (often containing fat globules)
| | <references/> |
| *Tissue gas formation (crepitus)
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| ===Management===
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| *Surgical exploration and debridement required to distinguish between anaerobic cellulitis and fasciitis or myonecrosis
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| ==Treatment==
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| #Surgical exploration and debridement
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| ##Indicated in setting of severe pain, toxicity, fever, elevated CK, w/ or w/o radiographic evidence
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| #Abx
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| ##Monotherapy with a beta-lactam/beta-lactamase inhibitor:
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| Piperacillin-tazobactam• 3.375 or 4.5 g IV every six hours
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| Ticarcillin-clavulanate 3.1 g IV every four hours
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| Combination third generation cephalosporin PLUS metronidazole:
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| Ceftriaxone plus 1 g IV every 24 hours or 2 g IV every 12 hours for CNS infections
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| Metronidazole 500 mg IV every eight hours
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| Alternative empiric regimens
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| Combination fluoroquinoloneΔ PLUS metronidazole:
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| Ciprofloxacin or 400 mg IV every 12 hours
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| Levofloxacin plus 500 or 750 mg IV once daily
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| Metronidazole 500 mg IV every eight hours
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| Monotherapy with a carbapenem◊:
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| Imipenem-cilastatin 500 mg IV every six hours
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| Meropenem 1 g IV every eight hours
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| Doripenem 500 mg IV every eight hours
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| Ertapenem§ 1 g once daily
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| arbapenem or beta-lactam/beta-lactamase inhibitor (table 4), together with clindamycin (dosed at 600 to 900 mg intravenously every eight hours, for its antitoxin effects against toxin-elaborating strains of streptococci and staphylococci) [30,59-64], as well as an agent with activity against methicillin-resistant S. aureus (MRSA) (such as vancomycin, daptomycin, or linezolid) (table 5).
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| Options for carbapenems include imipenem, meropenem, or ertapenem; options for beta-lactam/beta-lactamase inhibitors include piperacillin/tazobactam, ampicillin/sulbactam, or ticarcillin/clavulanate. Patients with hypersensitivity to these agents may be treated either with an aminoglycoside or a fluoroquinolone, plus metronidazole.
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| Antibiotic treatment should be tailored to Gram stain, culture, and sensitivity results when available. In the setting of known group A streptococcal or other beta-hemolytic streptococcal infection, treatment may be narrowed to the combination of penicillin (4 million units intravenously every four hours in adults >60 kg in weight and with normal renal function) and clindamycin (600 to 900 mg intravenously every eight hours) [30]. Therapy against MRSA may be discontinued after methicillin-resistant staphylococcal infection has been excluded.
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| The optimal duration of antibiotic treatment has not been defined in clinical trials. Antibiotics should be continued until no further debridements are needed and the patient’s hemodynamic status has normalized; this duration must be tailored to individual patient circumstances
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| ==Source==
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| * UpToDate
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| [[Category:ID]] | | [[Category:ID]] |
