Impetigo

Basics

Description

  • Impetigo is a superficial skin infection seen frequently in children.
    • It is one of the most common skin and soft tissue infections observed in pediatrics.
    • Pyoderma and impetigo contagiosa are synonyms for impetigo.
  • Classification
    • Primary impetigo: direct bacterial invasion of previously normal skin
    • Secondary impetigo: infection at sites of minor skin trauma or underlying conditions
  • Types of impetigo
    • Nonbullous impetigo
      • Most common form, >70% of cases
      • Lesions begin as papules that progress to vesicles surrounded by erythema.
      • Subsequently, the papules mature into pustules that enlarge and break down to form thick, adherent, golden crusts.
    • Bullous impetigo
      • Vesicles enlarge to form bullae containing clear yellow fluid, which become darker and more turbid.
      • Ruptured bullae leave a honey-colored crust.
    • Ecthyma
      • An ulcerative form of impetigo
      • Lesions extend through the epidermis and deep into the dermis.

Epidemiology

  • Location
    • Most frequently in tropical or subtropical regions
    • Also prevalent in northern climates during summer months
  • Age:
    • Found most commonly in children aged 2 to 5 years
    • Can spread rapidly through child care centers and schools

Risk Factors

  • Poverty, overcrowding
  • Poor hygiene
  • Underlying scabies infection
  • Eczema

Etiology

  • Staphylococcus aureus: most common etiologic agent. Toxin-producing strains cause cleavage in superficial skin layer.
  • Impetigo due to community-associated methicillin-resistant S. aureus (CA-MRSA) has occurred in a minority of cases.
  • β-Hemolytic streptococci (primarily group A, but serogroups C and G have been implicated in some cases)

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