Impetigo is a contagious infection of the top layer of the skin, mostly in young children, caused by Staphylococcus aureus or group A Streptococcus. It spreads easily by touch and often starts on broken skin around the nose and mouth.
Key symptoms
- Red sores that ooze and form golden, honey-colored crusts
- Itching, little pain and usually no fever
- Sores around the nose and mouth, or on the arms and legs
- Bullous form: fragile blisters with clear or yellow fluid
- Other children at home or daycare with similar sores
What you find on exam
- Honey-colored crusts on a red base
- Flaccid blisters that leave a thin ring of scale (bullous impetigo)
- Punched-out crusted ulcers on the legs suggest ecthyma
- Nearby lymph nodes may be enlarged
Tests
- Diagnosis is usually clinical
- Culture of fluid or crust if widespread, recurrent or not improving
- Consider MRSA risk based on local rates and past infections
- Urinalysis if dark urine or swelling follows a strep skin infection
Treatment basics
- Few lesions: topical mupirocin or retapamulin after gently washing off crusts
- Many lesions or outbreaks: oral cephalexin
- Suspected MRSA: oral clindamycin, trimethoprim-sulfamethoxazole or doxycycline (age 8 and older)
- Hand washing, short nails and no sharing of towels
- Child can return to school or daycare 24 hours after starting antibiotics
Red flags
- Fever, spreading redness or a very ill child
- Large areas of peeling skin like a burn (staphylococcal scalded skin syndrome)
- Dark urine, face swelling or high blood pressure weeks later (post-streptococcal glomerulonephritis)
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.