skin & soft tissue infection

Differential diagnosis

• cellulitis
  • infection involves deeper dermis & subcutaneous fat
    • often on legs
    • borders less distinct than erysipelas
• erysipelas
  • infection of group A Streptococcus (beta-hemolytic Streptococcus)
  • very red erythematous skin lesion often on face
  • very distinct elevated borders
• impetigo
  • infection of group A Streptococcus or Staphylococcus
  • honey colored, crusted pustules
• Vibrio vulnificus
  • exposure to saltwater fish or shellfish in patients with cirrhosis
  • cellulitis, hemorrhagic bullae, sepsis
• Mycobacterium marinum
  • exposure to fish tanks or marine environments
  • chronic nodular infection of distal extremities
• Sporotrichosis
  • exposure to plants, thorns &/or soil
  • chronic nodular infection of distal extremities
• Capnocytophaga canimorsus
  • dog bite in a patient with asplenia
  • sepsis
• necrotizing fasciitis, myonecrosis
  • deep tissue infection, surgical emergency
  • swelling, erythema
  • pain out of proportion to physical examination
• subcutaneous abscess
  • Staphylococcus aureus
  • acute, tender, well delineated purulent papular lesion (abscess)
• folliculitis
  • due to Staohylococcus aureus
    • pustules, follicle-centered in beard, axillae, pubic areas & thighs
  • due to Pseudomonas aeruginosa
    • associated with hot tub or whirlpool exposure
    • erythematous papules & pustules, follicle-centered on trunk, axillae & buttocks

Management

• non-purulent cellulitis or erysipelas
  • no signs of systemic infection
    • oral penicillin, amoxicillin, cephalexin, dicloxacillin or clindamycin
  • signs of systemic infection
    • intravenous penicillin, ceftriaxone, cefazoline, clindamycin
• purulent cellulitis
  • mild-moderate, no signs of systemic infection
    • oral trimethoprim/sulfamethoxazole or doxycycline
  • extensive infection or signs of systemic infection
    • vancomycin (IV) or linezolid (oral/IV), daptomycin, telavancin, ceftaroline
• treat risk factors for recurrent cellulitis
  • lymphedema, Tinea pedis, chronic venous insufficiency
• impetigo
  • limited disease: topical mupirocin
  • more extensive disease: treat as non-purulent cellulitis
• folliculitis
  • Staphylococcus or Pseudomonas
  • spontaneous resolution more common than not
  • topical mupirocin, clindamycin, retapamulin
• human bites
  • clenched fist injury
    • prophylactic amoxicillin clavulanate
    • ampicillin sulbactam IV for infected wounds
• animal bites (without systemic symptoms)
  • amoxicillin clavulanate
• necrotizing fasciitis, myonecrosis, purple bullae or sloughing of skin
  • magnetic resonance imaging for necrotizing fasciitis or myonecrosis
  • surgical debridement
  • vancomycin + piperacillin tazobactam, imipenem or meropenem + clindamycin
• abscess, furuncle, carbuncle
  • primary treatment is incision & drainage
  • obtain gram stain prior to administration of antibiotics (if administered)
  • skin abscess may have higher rate of cure if incision & drainage is accompanied by antibiotic treatment with coverage for MRSA

Additional terms

• skin infection
• soft tissue infection