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SOFT TISSUE INFECTION

Cellulitis

  • Aetiology:

    • Usually​ caused by minor trauma (eg scratch or splinter)

    • Usually Staph aureus or group A streptococcus

  • Examination findings:​

    • Pain, swelling, erythema​

    • No abscess formation

  • Treatment:​

    • Antibiotics - IV or oral​

      • Prolonged and aggressive treatment usually required in diabetic and lymphoedema patients

      • Consider changing antibiotics to more aggressive second line if no response

      • Consider possibility of deep abscess and the need for surgical drainage if antibiotic therapy unsuccessful

    • Consider inpatient admission

    • Useful adjuncts - Warm soaks, splinting and elevation

Cellulitis

Necrotising fasciitis

  • Life- and limb-threatening

  • Rapidly progressive infection of the subcutaneous tissue and fascia

  • Also known as Fournier's gangrene when affecting genitalia or perineum

  • Risk factors:

    • Diabetes​

    • Elderly

    • Immunocompromised

    • Cancer

  • Classification (Misiakos et al)​

    • Type 1 (polymicrobial)​

      • Obligate and facultative anaerobes​

      • Trunk and perineum

    • Type 2 (monomicrobial)​

      • Beta haemolytic Strep A​

      • Limbs

    • Type 3 

      • Clostridium sp, Gram negative bacteria, Vibrio vulfinicus​

      • Limbs, trunk, perineum

    • Type 4​

      • Candida sp​

      • Limbs, trunk, perineum

  • Clinical findings​

    • Rapidly progressive cyanosis/ dullness on skin​

    • Bullae/blistering

    • Patients usually appear unwell, pale, in shock

    • Severely painful

    • Foul-smelling, "dishwater" pus

    • LRINEC score

      • Less important clinically​

      • CRP

        • ≥ 150 - 4 points

      • WBC

        • <15: 0 points

        • 15–25: 1 point

        • >25: 2 points

      • ​Hemoglobin (g/dL)

        • >13.5: 0 points

        • 11–13.5: 1 point

        • <11: 2 points

      • Sodium (mmol/L)

        • <135: 2 points

      • Creatinine (umol/L)

        • >141: 2 points

      • Glucose (mmol/L)

        • >10: 1 point

  • Treatment​

    • Emergency, aggressive debridement of nonviable tissue to fascia​

      • Send tissue to microbiology for immediate Gram stain for confirmation

      • High-dose, broad-spectrum IV antibiotics​ guided by microbiologist or trust guidelines

    • Leave wound open until infection completely treated

    • Monitor in critical care unit

    • Repeat debridement until infection is under control

    • Soft tissue reconstruction once infection treated and patient stable

Necrotising fasciitis

Gas gangrene

  • May be rapidly fatal

  • Aetiology

    • Clostridium sp​ (C perfringens most common)

      • α-toxin (alpha) causes myonecrosis, haemolysis and myocardial depression by inhibition of the calcium pump

      • θ-toxin (theta) is a haemolysin and is cardiotoxic

      • κ-toxin (kappa) destroys blood vessels through collagenase activity

      • Hydrogen sulfide and carbon dioxide gas are produced

  • Clinical findings

    • Similar presentation to necrotising fasciitis but spreads more rapidly​

  • Management​

    • Emergency surgical debridement​

    • Leave wounds open

    • Frequent dressing changes

    • IV antibiotics guided by microbiology

Gas gangrene
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