Necrotizing soft tissue infections: Difference between revisions

Revision as of 21:26, 21 March 2013

Background

Includes necrotizing forms of cellulitis, myositis, and fasciitis
Two types:
- Type 1: polymicrobial infection
- Type 2: group A strep
  - May occur in healthy individuals with no PMH
  - May occur via hematogenous spread from throat to site of blunt trauma

Necrotizing Fasciitis

Risk Factors

DM
Drug use
Obesity
Immunosuppression
Recent surgery
Traumatic wounds

Clinical Features

Skin exam
- Erythema(without sharp margins)
- Exquisitely tender (pain out of proportion to exam)
- Skip lesions
- Hemorrhagic bullae
  - May be preceded by skin anesthesia (destruction of superficial nerves)
- Crepitus (in type I infections)
Swelling/edema may produce compartment syndrome
Constitutional
- Fever
- Tachycardia
- Systemic toxicity

Necrotizing Myositis

Much rarer than nec fasc
May be preceded by skin abrasions, blunt trauma, heavy exercise
Most patients are otherwise healthy (DM and other underlying conditions do not appear to increase risk)

Necrotizing Cellulitis

Pts are often much less toxic compared with nec fasc/nec myo
Two types:
- Anaerobic infection (clostridial and nonclostridial)
- Meleney's synergistic gangrene
  - Rare infection that occurs in postop pts
  - Characterized by slowly expanding indolent ulceration that is confined to superficial fascia
  - Results from synergistic interaction between S. aureus and microaerophilic streptococci

Risk Factors

Trauma
Surgical contamination
Spread of infection from bowel to perineum, abdominal wall, or lower extremities

Clinical Features

Thin, dark, sometimes foul-smelling wound drainage (often containing fat globules)
Tissue gas formation (crepitus)

Management

Surgical exploration and debridement required to distinguish between anaerobic cellulitis and fasciitis or myonecrosis

Source

UpToDate

Authors:

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 ==Background==
-===Fasciitis===
+* Includes necrotizing forms of cellulitis, myositis, and fasciitis
-# does not involve muscle- but can spread to muscle
+* Two types:
-# syst toxicity
+** Type 1: polymicrobial infection
-# skin c blebs, crepitus, necrosis
+** Type 2: group A strep
-# risks- dm, pvd, trauma or recent surg
+*** May occur in healthy individuals with no PMH
-# pain varies since nerve endings damaged- cessation or absence of pain may indicate worsening sxs
+*** May occur via hematogenous spread from throat to site of blunt trauma
-# necrosis of fat can lead to soapanification and hypocalemia
-# pcn/gent/clinda
+==Necrotizing Fasciitis==
+===Risk Factors===
+*DM
+*Drug use
+*Obesity
+*Immunosuppression
+*Recent surgery
+*Traumatic wounds
-===Myositis===
+===Clinical Features===
-# myonecrosis- deep soft- tissue infection with  death of muscle
+*Skin exam
-# often with little skin changes but does have gas  formation
+**Erythema(without sharp margins)
-# result of trauma or surgical wounds
+**Exquisitely tender (pain out of proportion to exam)
-# exotoxin of clostridia damages and kills muscle,  setting up anaerobic environment that promotes further bacterial growth
+**Skip lesions
-# odor described as "sickly sweet:
+**Hemorrhagic bullae
-# pt usually anuric
+***May be preceded by skin anesthesia (destruction of superficial nerves)
-# muscle appears cooked or dead, does not bleed  when cut or retract when pinched
+**Crepitus (in type I infections)
+*Swelling/edema may produce compartment syndrome
+*Constitutional
+**Fever
+**Tachycardia
+**Systemic toxicity
-===Necrotizing Fasciitis===
-# can occur p minor trauma
-# mortality 20- 50%
-==== Microorganisms ====
-#Type I Polymicrobrial- Anaerboic (mixed) staph, proteus, pseudomonas
-#Type 2 Streptococcal (toxin-generating)
-#Type 3 Clostridium Perfringens (gas gangrene)
-#Grp A beta hemolytic strep pyogenes releases substance in cell wall that causes separation of the dermal connective tissue resulting in continued inflammation and necrosis
-== Diagnosis ==
+==Necrotizing Myositis==
+* Much rarer than nec fasc
+* May be preceded by skin abrasions, blunt trauma, heavy exercise
+* Most patients are otherwise healthy (DM and other underlying conditions do not appear to increase risk)
-"Hard Signs"
-#Hypotension
+==Necrotizing Cellulitis==
-#Gas on XR
+*Pts are often much less toxic compared with nec fasc/nec myo
-#Skin necrosis
+* Two types:
-#Bullae
+**Anaerobic infection (clostridial and nonclostridial)
-#Crepitance
+**Meleney's synergistic gangrene
+***Rare infection that occurs in postop pts
+***Characterized by slowly expanding indolent ulceration that is confined to superficial fascia
+***Results from synergistic interaction between S. aureus and microaerophilic streptococci
-Other common signs/symptoms
+===Risk Factors===
+*Trauma
+*Surgical contamination
+*Spread of infection from bowel to perineum, abdominal wall, or lower extremities
-#Systemic toxicity
+===Clinical Features===
-#Numbness or deep pain out of proportion to exam
+*Thin, dark, sometimes foul-smelling wound drainage (often containing fat globules)
-#Violaceous or hemorrhagic appearance
+*Tissue gas formation (crepitus)
-#Pain beyond margins of cellulitis
-#Skip lesions
-Other
+===Management===
+*Surgical exploration and debridement required to distinguish between anaerobic cellulitis and fasciitis or myonecrosis
-#Meleney's synergistic gangrene- (progressive bacterial synergistic gangrene) involves superficial and deep fascial planes with thrombosis of subQ vessels and gangrene of tissue
-#Clostridial cellulitis- healthy muscle not invovled
-#Fournier's syndrome- necrotizing subq infection of perineum- risk factors include infection or trauma to the perineal area,, anal intercourse, scratches, chemical or thermal burns or diabetes. Obliteration of small branches of pudendal arteries results in dermal gangrene of perineal and scrotal skin.
-#Necrotizing Otitis Externa ([[Malignant Otitis Externa]]) - deep infection of cartillaginous-bony junction. Risk factors -Elderly, diabetics, immunocomprised. Clinically severe pain and signs of mastoditis. IV&nbsp;antibiotics against pseudomonas, aspergillus, mucorales. ENT&nbsp;consult stat. Complications- Basal skull infection with Cranial Nerves 8, 7, 10(vagus) initially.
-=== Labs ===
-#Hyponatremia, Na&lt;135
-#Leukocytosis
-=== Imaging ===
-#XR- gas
-#CT- most commonly used, up to 80% sensitive
-#UTZ- operator dependent
-#MRI- overly sensitive
-==Treatment==
-# wide surgical debridement and excision
-# IV ABX
-# Resuscitate as in sepsis
-Unclear benefit
-# hyperbaric O2
-# IVIG
-===Antibiotic Regimens===
-#Harbor:
-## community-acquired- Ceftriaxone/vanc/clinda +/- gent
-## hospital-acquired- Zosyn/vanc/clinda
-## pcn allergic- Cipro/vanc/clinda/gent
-#Other common regimens:
-## pen/ ox/ gent/ clinda- and also use vanco
 ==Source==
-/06 PANI
+* UpToDate
 [[Category:ID]]