Impetigo is a contagious bacterial infection that involves the superficial Human skin.[ The most common presentation is yellowish crusts on the face, arms, or legs.][ Less commonly there may be bullous which affect the groin or armpits.][ Fever is uncommon.][
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It is typically due to either Staphylococcus aureus or Streptococcus pyogenes.[ Diagnosis is typically based on the symptoms and appearance.][
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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.][ Healing generally occurs without scarring.][
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Impetigo affected about 140 million people (2% of the world population) in 2010.[ In some places the condition is also known as "school sores".][ Recurring infections can occur due to colonization of the nose by the bacteria.][ The name is from the Latin impetere meaning "attack".]
Signs and symptoms
Contagious impetigo
This most common form of impetigo, also called nonbullous impetigo, most often begins as a red sore near the nose or mouth which soon breaks, leaking pus or fluid, and forms a honey-colored wound healing,
Skin ulcers with erythema and scarring also may result from scratching or abrading the skin.
Bullous impetigo
Bullous impetigo, mainly seen in children younger than two years, involves painless, fluid-filled , mostly on the arms, legs, and trunk, surrounded by red and itchy (but not sore) skin. The blisters may be large or small. After they break, they form yellow scabs.[
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Ecthyma
Ecthyma, the nonbullous form of impetigo, produces painful fluid- or pus-filled sores with redness of skin, usually on the arms and legs, become ulcers that penetrate deeper into the dermis. After they break open, they form hard, thick, gray-yellow scabs, which sometimes leave scars. Ecthyma may be accompanied by swollen in the affected area.[
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Causes
Impetigo is primarily caused by Staphylococcus aureus, and sometimes by Streptococcus pyogenes.
Predisposing factors
Impetigo is more likely to infect children ages 2–5, especially those that attend school or day care.[ 70% of cases are the nonbullous form and 30% are the bullous form.][ Impetigo occurs more frequently among people who live in warm climates.]
Transmission
The infection is spread by direct contact with or with human nose carriers. The incubation period is 1–3 days after exposure to Streptococcus and 4–10 days for Staphylococcus.
Diagnosis
Impetigo is usually diagnosed based on its appearance. It generally appears as honey-colored scabs formed from dried sebum 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.[
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Other conditions that can result in symptoms similar to the blistering form include other bullous skin diseases, , and necrotizing fasciitis.[
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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.
Treatment
, either as a cream or by mouth, are usually prescribed. Mild cases may be treated with mupirocin ointments. In 95% of cases, a single seven-day antibiotic course results in resolution in children.[ However, the National Institute for Health and Care Excellence (NICE) as of February 2020 recommends a hydrogen peroxide 1% cream antiseptic rather than topical antibiotics for localised non-bullous impetigo in otherwise well individuals.]
More severe cases require oral antibiotics, such as dicloxacillin, flucloxacillin, or erythromycin. Alternatively, amoxicillin combined with clavulanate potassium, (first-generation) and many others may also be used as an antibiotic treatment. Alternatives for people who are seriously allergic to penicillin or infections with methicillin-resistant Staphococcus aureus include doxycycline, clindamycin, and trimethoprim-sulphamethoxazole, although doxycycline should not be used in children under the age of eight years old due to the risk of drug-induced tooth discolouration.
Prognosis
Without treatment, individuals with impetigo typically get better within three weeks.[ Complications may include cellulitis or poststreptococcal glomerulonephritis.][ Rheumatic fever does not appear to be related.][
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Epidemiology
Globally, impetigo affects more than 162 million children in low- to middle-income countries.[ The rates are highest in countries with low available resources and is especially prevalent in the region of Oceania.]
History
Impetigo was originally described and differentiated by the English dermatologist William Tilbury Fox around 1864.
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