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Definition: impetigo from Philip's Encyclopedia

Contagious skin condition caused by streptococcal or staphylococcal infection. It causes multiple, spreading lesions with yellowish-brown crusts.

Summary Article: Impetigo
from Black's Medical Dictionary, 42nd Edition

A contagious skin disease, more common in children, caused usually by Staphylococcus aureus and less often by Streptococcus pyogenes. The itching rash is seen especially on the face but may spread widely. Vesicles and pustules erupt and dry to form yellow-brown scabs. Untreated, the condition may last for weeks. In very young infants, large blisters may form (bullous impetigo).


Crusts should be gently removed with SALINE. Mild cases respond to frequent application of mupiricin or NEOMYCIN/BACITRACIN ointment; more severe cases should be treated orally or, sometimes, intravenously with FLUCLOXACILLIN or one of the CEPHALOSPORINS. If the patient is allergic to penicillin, ERYTHROMYCIN can be used.

For severe, intractable cases, an oral retinoid drug called isotretinoin (commercially produced as Roaccutane®) can be used. It is given systemically but treatment must be supervised by a consultant dermatologist, as serious side-effects, including possible psychiatric disturbance, can occur. The drug is also teratogenic (see TERATOGENESIS), so women who are, or who may become, pregnant must not take isotretinoin. It acts mainly by suppressing SEBUM production in the sebaceous glands and can be very effective. Recurrent bouts of impetigo should raise suspicion of underlying SCABIES or head lice. Bactericidal soaps and instilling an antibiotic into the nostrils may also help.

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