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AlexanderSalava

Impetigo and other Pyoderma

Essentials

  • Impetigo spreads easily in the family, day-care centre and school.
  • Remember the possibility of post-infectious glomerulonephritis in streptococcal impetigo.

Clinical features

  • Children are most commonly affected.
  • Streptococcal infection typically makes crusts or small ulcerations; staphylococcal infection tends to make blisters (pictures 1 2).
  • "Pemphigus neonatorum" (picture 3) in infants is actually impetigo. The infection is caused by Staphylococcus aureus phage type II.
  • The crusts usually appear in the surroundings of the nostrils (picture 4), on the chin (picture 5), and generally on the face (pictures 67).
  • Thick crusts are characteristic.

Differential diagnosis

  • Primary herpes simplex infection may resemble impetigo.
  • Ringworm (tinea corporis)
  • If impetigo tends to recur in the scalp and neck consider the possibility of head lice.

Causative agents

  • Staphylococcus aureus
  • Group A beta-haemolytic streptococci (picture 8)
  • Eczema (picture 9) may predispose the skin to impetigo.
  • The infection usually spreads by autoinoculation.
  • Recurrences are often caused by bacteria remaining in the nostrils from where they are re-spread by fingering of the nose.

Treatment

  • Treatment is started on the basis of the clinical presentation.
  • If the disease is confined to a small area the treatment consists of soaking the crusts so that they are detached, and applying an antimicrobial ointment (fusidic acid Interventions for Impetigo or a combination of neomycin and bacitracin).
  • If the disease is more widespread (> 6 cm2 ) use a systemic antimicrobial effective against S. aureus, primarily cephalexin Systemic Antibiotics in the Treatment of Impetigo in Children or flucloxacillin 750-1 000 mg 3 times daily. Duration of treatment is usually 7-10 days. Patients with cephalosporin allergy can be treated with clindamycin.
  • If the patient has eczema a topical preparation containing a glucocorticoid and an antimicrobial agent should be used together with systemic antimicrobials until the skin is intact.
  • Do not forget further treatment of the eczema.
  • The most common reasons for poor response to treatment
    • The diagnosis is incorrect. The patient has scabies, lice, or ringworm.
    • The crusts have not been soaked and removed. The bacteria can survive under crusts.
    • The underlying eczema has not been treated.
    • The nostrils serve as reservoir for bacteria (apply neomycin-bacitracin or fusidic acid ointment into the nostrils. Mupirocin should not be used for this disease as its use should be limited to the eradication of methicillin-resistant Staphylococcus aureus).