General Dermatology - Patients ask Dr. Ringpfeil answers
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Impetigo is a superficial bacterial infection of the skin caused by Staphylococcus aureus, group A Streptococcus or a mixture of both. Staphylococcus aureus is the most common causative agent. The infection can either be primary, developing within minor breaks in the skin, or secondary to another inflammatory skin condition. Common inflammatory skin conditions that can become secondarily impetiginized are atopic dermatitis, contact dermatitis and less commonly psoriasis. Chronic scratching causes disruption in the skin surface which can invite bacteria to invade. There are two types of impetigo: blistering (bullous) and not blistering. The non-blistering variety is by far more common and is characterized by the appearance of honey-colored crusts. It is often seen on the face but can occur on any part of the body. Bullous impetigo is characterized by blisters which occur on normal appearing skin. Bullous impetigo is seen primarily in children. Both forms are contagious and can quickly spread through skin-to-skin contact.
Impetigo can be diagnosed by its characteristic appearance but a bacterial culture can be performed to confirm the diagnosis if needed. In older individuals, a biopsy of bullous impetigo may be necessary to differentiate it from other blistering diseases.
Topical treatment includes cleansing of the affected area with an antibacterial cleanser several times daily. In children, a mild antibacterial cleanser such as Cetaphil antibacterial is preferred. In localized disease, this should be followed by application of petrolatum, zinc paste, over-the-counter or prescription strength topical antibiotic several times daily. If the infection is widespread an oral antibiotic may be necessary. Due to the contagious nature of the infection, affected individuals should be cautious to avoid skin-to-skin contact with others and should not share personal hygiene products such as razors and towels.
Impetigo is usually asymptomatic but may be occasionally itchy. It is not painful. Treatment will usually eradicate the rash within days.
Primary infection can be prevented by avoidance of close contacts that have impetigo. Sharing of towels, washcloths, clothing, bed linens and razors should be avoided. Secondary impetigo can be prevented through management of underlying skin conditions such as atopic dermatitis and psoriasis and the avoidance of scratching. People who get recurrent episodes of impetigo may be carriers of staphylococcus aureus bacterium in their nostrils or in skin folds. Eradication of the bacteria from this location may prevent future outbreaks. This may be accomplished by applying mupirocin cream to the inner nares for 7 to 10 day period.