Curriculum · ENT, Ophthalmology, and Dermatology
Impetigo
What it is
Impetigo is a highly contagious superficial bacterial infection of the skin. It is frequently seen in children at 2-5 years of age, and is transmitted through direct contact or fomites; within one patient the route of transmission is autoinoculation of the infected exudate. It is classified clinically as non-bullous and bullous impetigo. Non-bullous impetigo is most often caused by Staphylococcus aureus and can also be caused by group A beta-haemolytic streptococcus, so the usual organisms are Staphylococcus aureus or Streptococcus pyogenes. Bullous impetigo is caused by toxin-producing S. aureus. Among skin and soft tissue infections, impetigo and ecthyma fall on the purulent side, with furuncle, carbuncle and abscess. On the other side of that split, the non-purulent infections are cellulitis, necrotizing fasciitis and erysipelas.
How it presents
In non-bullous impetigo the initial lesions are small vesicles or pustules (< 2 cm) that rupture and become a honey-colored crust with a moist erythematous base. The crust is golden and confluent and is typically found around the mouth. Regional lymphadenopathy is commonly present. Bullous impetigo commonly affects neonates. It presents with flaccid bullae with sharp margins, and systemic symptoms may include weakness, fever and diarrhea.