- Clinical science
Impetigo is an infectious, predominantly pediatric skin disease caused by the bacteria Staphylococcus aureus or, less commonly, Streptococcus pyogenes (group A Streptococcus, GAS). There are both bullous and nonbullous variants. The disease causes honey-colored, crusted lesions with surrounding erythema and typically affects the face, but may also manifest on the extremities. While the diagnosis is usually made based on clinical findings, it can be confirmed with a bacterial culture. The first-line treatment for mild impetigo is a topical antibiotic (mupirocin), which typically resolves the infection without complications. An additional systemic antibiotic may be indicated in more severe cases.
- Age: primarily affects children (especially between 2–6 years of age)
- Prevalence: high in developing countries and underprivileged populations
- Impetigo is highly contagious and can cause epidemics in preschools or schools.
Impetigo is the most common bacterial skin infection among children!
Epidemiological data refers to the US, unless otherwise specified.
- Staphylococcus aureus: ∼ 80% of cases
- Streptococcus pyogenes (GAS): ∼ 10% of cases: causes nonbullous impetigo only
- S. aureus and GAS coinfection: ∼ 10% of cases
- Predisposing factors
- Route of infection
Nonbullous impetigo (∼ 70% of cases)
Lesions: papules → small vesicles surrounded by erythema → pustules that rupture → oozing secretion that dries→ honey-colored crusts → heal without scarring
- Negative Nikolsky sign
- Lesions: papules → small vesicles surrounded by erythema → pustules that rupture → oozing secretion that dries→ honey-colored crusts → heal without scarring
- Bullous impetigo (∼ 30% of cases)
- Ecthyma: ulcerative impetigo that extends into the dermis; (coin-sized, superficial ulcer, with a 'punched-out' appearance)
- Systemic signs: possible in severe cases (e.g., fever, malaise, weakness)
Impetigo should be suspected in children presenting with honey-colored crusts around the mouth and nose!
- Generally diagnosed based on clinical presentation
- Microbiological culture → detection of causative pathogen
- Indications: inconclusive diagnosis, recurrence despite treatment
- Conditions that cause localized inflammation
- Conditions that cause bullae
The differential diagnoses listed here are not exhaustive.
- Wound cleansing with antibacterial washes (e.g., chlorhexidine)
- Nonbullous impetigo with single lesions or small areas: topical antibiotics (mupirocin, retapamulin)
- Bullous impetigo, ecthyma, or severe non-bullous impetigo
- Advise patients and caregivers to wash hands regularly.
- To prevent the spread of the disease, children should receive antibiotic treatment for at least 24 hours before returning to daycare or school.