Soft Tissue Infections

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Soft Tissue Infections

• Dr Cardinal

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Objectives

• Discuss the features of common skin infections as
  well as necrotizing skin infections including
• Epidemiology
• Pathophysiology
• Clinical features
• Treatment

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Necrotizing Soft Tissue Infections

• Gas gangrene (Clostridial myonecrosis)
• Gas gangrene (Nonclostridial myonecrosis)
• Streptococcal myositis
• Necrotizing fasciitis (polymicrobial)
• Necrotizing fasciitis ( Group A Streptococcus)
• Necrotizing cellulitis

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Gas Gangrene (Clostridial)

• Epidemiology
• About 1000 cases reported to CDC yearly
• Pathophysiology
• Seven sp Clostridium
• C. perfringes 80-95
• Soil, GI tract, Female GU
• Release endotoxins
• Cardiodepressant
• Hydrolyzes cell membranes

C. perfringes
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Gas Gangrene (Clostridial)

• Clinical
• Incubation 3 days
• Pain out of proportion
• Heaviness of affected part
• Edema, brown discoloration
• /- crepitance
• Serosanguineous discharge
• Bullae
• Fever, tachycardia
• Confusion, sepsis
• Uterine myonecrosis after C-section
• Deepest of the necrotizing soft tissue infections

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Gas Gangrene (Clostridial)

• Clinical
• X-Ray/CT gas
• Treatment
• Resuscitation
• Antibiotics
• Pen G Clindamycin
• Augmentin
• Imipenem
• Unasyn
• Surgical debridement
• Hyperbaric oxygen therapy (HBO)

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Gas Gangrene (Nonclostridial)

• Pathophysiology
• Mixed infections
• Aerobic / anaerobic
• Bacteria by prevalence
• Enterococcus
• Staphylococcus
• Alpha-Streptococci
• E. coli
• Klebsiella
• Proteus
• Bacteroides

E. Faecalis in blood culture
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Gas Gangrene (Nonclostridial)

• Clinical
• Similar to Clostridial except
• Pain at onset less
• Delayed presentation (2-10 days)
• Mortality 43

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Gas Gangrene (Nonclostridial)

• Treatment
• Broad spectrum antibiotics
• Aerobic gram / -
• Anerobes
• Unasyn
• Timentin
• Zosyn
• Imipenem
• Floroquinolone added if fresh water infection
  suspected
• Surgical debridement
• HBO

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Streptococcal Myositis

• Rare muscle infection
• Group A Streptococcus
• Usually S. pyogenes
• flesh eating bacteria
• Epidemiology
• Age 20-50
• Otherwise healthy

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Streptococcal Myositis

• Clinical
• Difficult to distinguish from other myonecrosis
• No gas production
• High rate of bacteremia
• Toxic shock syndrome 4-6 hours after admission
• Mortality 80-100

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Streptococcal Myositis

• Treatment
• Aggressive management of shock
• Early vasopressors in shock
• Antibiotics
• IV Pen G / Clindamycin
• IVIG 2g/kg
• Neutralizes exotoxins
• Surgical debridement

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Necrotizing Fasciitis (Polymicrobial)

• Necrosis of subQ and fascia
• Does not spread to muscle as clostridial /
  nonclostridial myonecrosis
• Also grouped into tabloid term flesh eating
  bacteria

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Necrotizing Fasciitis (Polymicrobial)

• Epidemology
• 10-20 cases per 100,000 people
• DM, PVD, IVDA, smoking
• Pathophysiology
• Mixed aerobic / anerobic
• Average 4.4 organisms per infection
• Usually antecedent trauma / bite
• Bacteremia 25-30
• Mortality 25-50

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Necrotizing Fasciitis (Polymicrobial)

• Clinical
• Pain out of proportion
• Erythematous / edematous
• Discoloration, vesicles
• Fever, tachycardia
• May progress rapidly
• Crepitus as late finding
• Finger test

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Necrotizing Fasciitis (Polymicrobial)

• Treatment
• Aggressive resuscitation
• Avoidance of vasopressors
• Antibiotics as in myonecrosis
• Surgery
• HBO

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Necrotizing Fasciitis (Group A Streptococcus)

• Epidemiology
• 10-20 cases per 100,000
• Mortality 20-60
• Increased risk with
• Varicella lesions
• NSAID use

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Necrotizing Fasciitis (Group A Streptococcus)

• Clinical
• Same as polymicrobial except
• No gas formation
• More rapid progression
• More prone to bacteremia
• Toxic shock more common

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Necrotizing Fasciitis (Group A Streptococcus)

• Treatment
• Initial broad spectrum Abx
• Narrowed to PCN and Clindamycin after culture
• Clindamycin
• Synergistic to PCN
• Suppresses toxin formation
• Promotes phagocytosis
• Suppresses PCN
• binding protein
• HBO of little use (aerobic organism)

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Necrotizing Cellulitis

• Most superficial necrotizing soft tissue
  infection
• Involves skin and subQ
• Pathophysiology
• Associated with antecedent trauma / bite
• Common in skin popping
• Usually polymicrobial
• Clostridium most common
• C. perfringens in trauma
• C. septicum in malignancy and spontaneous
  infection

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Necrotizing Cellulitis

• Clinical
• Pain at site. Less than seen in deeper infections
• Eccymotic or necrotic center
• Vesicles or blebs possible
• Crepitence /-
• Mild or no systemic symptoms

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Necrotizing Cellulitis

• Treatment
• Surgical debridement (usually curative)
• Broad spectrum abx

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Cellulitis

• Local soft tissue inflammation
• from bacterial invasion
• Epidemiology
• 1.3 of ER vistis
• 61 Male, Mean age 46
• Usually extremities
• Only 5 have predisposing factors

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Cellulitis

• Pathophysiology
• Adults Staph/Strep spp. most common
• Children H. influenza most common
• Diabetics consider Enterobacteriaceae
• Most bacterial organism cleared from body with 12
  hours. Majority of symptoms are from host immune
  response

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Cellulitis

• Clinical
• Local inflammation, tenderness, warmth, erythema,
  induration
• Lymphangitis uncommon concerning
• Bacteremia uncommon in healthy hosts

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Cellulitis

• Treatment outpatient
• Dicloxacillin
• Macrolide
• Azithromycin
• Clarithromycin
• Augmentin
• Treatment inpatient
• Involving head or neck
• IV abx

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Erysipelas

• Superficial cellulitis with lymphatic involvement
• Usually from Group A Streptococcus
• Antecedent trauma / bite or dermatoses
• Lower extremities now most common

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Erysipelas

• Clinical
• Abrupt onset
• High fever, chills, malaise and nausea prodrome
• Area of erythema with burning develops over next
  2 days
• Red, shiny, hot plaque, sharply demarcated

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Erysipelas

• Treatment usually inpatient
• Pen G IV
• Nafcillin
• Rocephin
• Augmentin
• Imipenem in severe

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Cutaneous Abscesses

• Pathophysiology
• Requires loss of skin integrity
• Usually caused by common colonizers
• Scalp/trunk/extremities
• Staph aureus, epidermidis
• Intriginous/perineal
• E. coli, P. mirabilis
• Axilla
• P. mirabilis

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Cutaneous Abscesses

• Clinical
• Swelling, tenderness, erythema
• Fluctuance, induration, drainage
• Systemic spread unusual in healthy
• Lymphadenitis, fever

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Cutaneous Abscesses

• Specific abscesses
• Bartholin gland abscess
• Paronychia and felons
• Hidradenitis suppurativa
• Infected sebaceous cyst
• Perirectal abscess
• Pilonidal abscess

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Cutaneous Abscesses

• Staphylococcal abscesses
• Continuum of severity
• Folliculitis
• Furuncle (boil)
• Carbuncle

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Cutaneous Abscesses

• Treatment
• Incision and drainage
• Wide excision if necessary (furuncle)
• Antibiotics
• Always in high risk groups
• Controversial in healthy persons

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Sporotrichosis

• Mycotic infection
• Sporothrix schenckii
• Common in soil and on vegetation
• Thermally dimorphic
• Traumatic inoculation

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Sporotrichosis

• Clinical
• Incubation 3 weeks
• Crusted ulcer or plaque
• at site
• Local lymphadenitis common
• Skip lesions along lymphatics
• Rarely systemic
• Meningitis
• Pulmonary

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Sporotrichosis

• Diagnosis
• Clinically / History
• Fungal cultures
• Tissue biopsy
• Treatment
• Itraconazole for 6 months

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Questions?