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For further information, see CMDT Part 6-25: Impetigo

Key Features

Essentials of Diagnosis

  • Superficial blisters filled with purulent material that rupture easily

  • Crusted superficial erosions

  • Positive Gram stain and bacterial culture

General Considerations

  • A contagious and autoinoculable infection of the skin caused by staphylococci or rarely streptococci

  • In temperate climates, most cases are associated with Staphylococcus aureus infection

  • Streptococcus species are more common in tropical climates

Clinical Findings

Symptoms and Signs

  • The lesions consist of macules, vesicles, bullae, pustules, and honey-colored gummy crusts that when removed leave denuded red areas

  • The face and other exposed parts are most often affected

  • Ecthyma is a deeper form of impetigo caused by staphylococci or streptococci, with ulceration and scarring; it occurs frequently on the extremities

Differential Diagnosis

  • Contact dermatitis (acute)

  • Herpex simplex

Diagnosis

  • Gram stain and culture confirm the diagnosis

Treatment

  • Soaks and scrubbing can be beneficial, especially in unroofing lakes of pus under thick crusts

  • For infections limited to small areas, first-line topical treatment options include

    • Mupirocin

    • Ozenoxacin

    • Retapamulin

  • For widespread infections, or in immunosuppressed individuals, use systemic antibiotics

    • Cephalexin, 250 mg four times daily orally

    • Doxycycline, 100 mg twice daily orally, or trimethoprim-sulfamethoxazole, double-strength twice daily orally, can be used for penicillin allergy and methicillin-resistant S aureus

  • Recurrent impetigo, which is due to nasal carriage of S aureus, is treated with rifampin, 300 mg orally twice daily, or mupirocin intranasal ointment applied intranasally twice daily for 5 days

  • Bleach baths (1/4 to 1/2 cup per 20 L of bathwater for 15 minutes 3–5 times weekly) for all family members may help reduce the spread

Outcome

Prevention

  • Individuals should not share towels if there is a case of impetigo in the household

References

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Galli  L  et al; Italian Pediatric Infectious Diseases Society; Italian Pediatric Dermatology Society. Common community-acquired bacterial skin and soft-tissue infections in children: an intersociety consensus on impetigo, abscess, and cellulitis treatment. Clin Ther. 2019 Mar;41(3):532–51.
[PubMed: 30777258]
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Kosar  L  et al. Management of impetigo and cellulitis: Simple considerations for promoting appropriate antibiotic use in skin infections. Can Fam Physician. 2017 Aug;63(8):615–8.
[PubMed: 28807958]

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