• A contagious, superficial, intraepidermal infection occurring prominently on exposed areas of the face and extremities, most often seen in children
  • Primary impetigo (pyoderma): invasion of previously normal skin
  • Secondary impetigo (impetiginization): invasion at sites of minor trauma (abrasions, insect bites, underlying eczema)
  • Infected patients usually have multiple lesions.
  • Cultures are positive in >80% cases for Staphylococcus aureus either alone or combined with group A β-hemolytic streptococci; S. aureus is the more common pathogen since the 1990s.
  • Nonbullous impetigo: most common form of impetigo; formation of vesiculopustules that rupture, leading to crusting with a characteristic of golden appearance; local lymphadenopathy may occur.
  • Bullous impetigo: staphylococcal impetigo that progresses from small to large flaccid bullae (newborns/young children) caused by epidermolytic toxin release; ruptured bullae leaving brown crust; less lymphadenopathy; trunk more often affected; <30% of patients
  • Folliculitis: considered by some to be S. aureus impetigo of hair follicles
  • Ecthyma: a deeper, ulcerated impetigo infection often with lymphadenitis
  • System(s) affected: skin/exocrine
  • Synonym(s): pyoderma; impetigo contagiosa; impetigo vulgaris



  • Predominant sex: male = female
  • Predominant age: children aged 2 to 5 years

In the United States: not reported but common

Pediatric Considerations

  • Poststreptococcal glomerulonephritis may follow impetigo (in young children).
  • Impetigo neonatorum may occur due to nursery contamination.

Etiology and Pathophysiology

  • Coagulase-positive staphylococci: pure culture ~50–90%; more contagious via contact
  • β-Hemolytic streptococci: pure culture only ~10% of the time (primarily group A)
  • Mixed infections of streptococci and staphylococci are common; data suggest increasing importance of staphylococci over the past decades.
  • Methicillin-resistant S. aureus (MRSA) detected in some cases
  • Direct contact or insect vector
  • Can result from contamination at trauma site
  • Regional lymphadenopathy

Risk Factors

  • Warm, humid environment
  • Tropical or subtropical climate
  • Summer or fall season
  • Minor trauma, insect bites, breaches in skin
  • Poor hygiene, poverty, crowding, epidemics, wartime
  • Familial spread
  • Poor health with anemia and malnutrition
  • Complication of pediculosis, scabies, chickenpox, eczema/atopic dermatitis
  • Contact dermatitis (Rhus spp.)
  • Burns
  • Contact sports
  • Children in daycare
  • Carriage of group A Streptococcus and S. aureus

General Prevention

  • Close attention to family hygiene, particularly hand washing among children
  • Covering of wounds
  • Avoidance of crowding and sharing of personal items
  • Treatment of atopic dermatitis

Commonly Associated Conditions

  • Malnutrition and anemia
  • Crowded living conditions
  • Poor hygiene
  • Neglected minor trauma
  • Any chronic/underlying dermatitis
  • Can occur as coinfection with scabies

There's more to see -- the rest of this topic is available only to subscribers.