Back to Basics: A common rash

Mon, 10/07/2019 - 5:00am

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12 yo male with no significant pmh presents to the ED with a progressive rash on his feet over the past week. Afebrile and hemodynamically stable. No improvement with topical mupirocin and PO Clindamycin. Derm photos below. Diagnosis? Treatment plan?

Bullous impetigo

Appearance:

Bullae and/or blisters, clear-yellow fluid that turns dark, leaves yellow crust when rupture

Cause:

-- Staph aureus (MSSA or MRSA) - Epidermolytic toxin A and B act locally to cause blisters

-- Also consider Strep pyogenes (GAS)

Treatment:

Spontaneous resolution in 2-3 weeks OR ...

Antibiotic options:

Mupirocin 2%	TID for 14 days
Cephalexin	25–50 mg/kg/24 hr PO ÷ Q6–12	MSSA or strep
Clindamycin	10–40 mg/kg/24 hr ÷ Q6–8 hr; max. dose: 1.8 g/24 hr	MRSA and strep
Trimethoprim- sulfamethoxazole	8–12 mg/kg/24 hr ÷ BID; max. dose: 160 mg/dose	MRSA, poor strep
Doxycycline	≤45 kg: 2.2–4.4 mg/kg/24 hr once daily–BID PO/IV >45 kg: 100–200 mg/24 hr ÷ once daily–BID PO/IV Max. dose: 200 mg/24 hr	MRSA, poor strep
Vancomycin	15 mg/kg Q6h	MRSA

References:

Hartman-Adams H, Banvard C, Juckett G. Impetigo: Diagnosis and Treatment. Am Fam Physician. 2014 Aug 15;90(4):229-35.

Bonfante G, Dunn A. Rashes in Infants and Children. In: Tintinalli JE, Stapczynski J, Ma O, Yealy DM, Meckler GD, Cline DM. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e New York, NY: McGraw-Hill; 2016.

Lee CK. Drug Dosages. In: Hughes HK, Kahl LK. The Harriet Lane Handbook, 21e, 2018