Impetigo is a bacterial infection that involves the superficial skin. The most common presentation is yellowish crusts on the face, arms, or legs. Less commonly there may be large blisters which affect the groin or armpits. The lesions may be painful or itchy. Fever is uncommon.It is typically due to either Staphylococcus aureus or Streptococcus pyogenes. Risk factors include attending day care, crowding, poor nutrition, diabetes mellitus, contact sports, and breaks in the skin such as from mosquito bites, eczema, scabies, or herpes. With contact it can spread around or between people. Diagnosis is typically based on the symptoms and appearance.Prevention is by hand washing, avoiding people who are infected, and cleaning injuries. Treatment is typically with antibiotic creams such as mupirocin or fusidic acid. Antibiotics by mouth, such as cefalexin, may be used if large areas are affected. Antibiotic-resistant forms have been found.Impetigo affected about 140 million people (2% of the world population) in 2010. It can occur at any age, but is most common in young children. In some places the condition is also known as "school sores". Without treatment people typically get better within three weeks. Recurring infections can occur due to colonization of the nose by the bacteria. Complications may include cellulitis or poststreptococcal glomerulonephritis. The name is from the Latin impetere meaning "attack".
70% of cases are the nonbullous form and 30% are the bullous form. Other factors can increase the risk of contracting impetigo such as diabetes mellitus, dermatitis, immunodeficiency disorders, and other irritable skin disorders. Impetigo occurs more frequently among people who live in warm climates. Transmission
The infection is spread by direct contact with lesions or with nasal carriers. The incubation period is 1–3 days after exposure to Streptococcus and 4–10 days for Staphylococcus. Dried streptococci in the air are not infectious to intact skin. Scratching may spread the lesions. Diagnosis
Impetigo is usually diagnosed based on its appearance. It generally appears as honey-colored scabs formed from dried serum and is often found on the arms, legs, or face. If a visual diagnosis is unclear a culture may be done to test for resistant bacteria. Differential diagnosis
Other conditions that can result in symptoms similar to the common form include contact dermatitis, herpes simplex virus, discoid lupus, and scabies.Other conditions that can result in symptoms similar to the blistering form include other bullous skin diseases, burns, and necrotizing fasciitis. Prevention
To prevent the spread of impetigo the skin and any open wounds should be kept clean and covered. Care should be taken to keep fluids from an infected person away from the skin of a non-infected person. Washing hands, linens, and affected areas will lower the likelihood of contact with infected fluids. Scratching can spread the sores; keeping nails short will reduce the chances of spreading. Infected people should avoid contact with others and eliminate sharing of clothing or linens.