| Impetigo | |
|---|---|
| Other names | School sores,[1] impetigo contagiosa |
 | |
| A case of impetigo on the chin | |
| Pronunciation | |
| Specialty | Dermatology,infectious disease |
| Symptoms | Yellowish skin crusts, painful[2][3] |
| Complications | Cellulitis,poststreptococcal glomerulonephritis[3] |
| Usual onset | Young children[3] |
| Duration | Less than 3 weeks[3] |
| Causes | Staphylococcus aureus orStreptococcus pyogenes which spreads by direct contact |
| Risk factors | Day care, crowding,poor nutrition,diabetes mellitus,contact sports, breaks in the skin[3][4] |
| Prevention | Hand washing, avoiding infected people, cleaning injuries[3] |
| Treatment | Based on symptoms[3] |
| Medication | Antibiotics (mupirocin,fusidic acid,cefalexin)[3][5] |
| Frequency | 140 million (2010)[6] |
Impetigo is a contagiousbacterial infection that involves the superficialskin.[2] The most common presentation is yellowish crusts on the face, arms, or legs.[2] Less commonly there may belarge blisters which affect thegroin orarmpits.[2] The lesions may be painful or itchy.[3]Fever is uncommon.[3]
It is typically due to eitherStaphylococcus aureus orStreptococcus pyogenes.[7] Risk factors include attendingday care, crowding,poor nutrition,diabetes mellitus,contact sports, and breaks in the skin such as frommosquito bites,eczema,scabies, orherpes.[3][4] With contact it can spread around or between people.[3] Diagnosis is typically based on the symptoms and appearance.[3]
Prevention is byhand washing, avoiding people who are infected, and cleaning injuries.[3] Treatment is typically withantibiotic creams such asmupirocin orfusidic acid.[3][5] Antibiotics by mouth, such ascefalexin, may be used if large areas are affected.[3]Antibiotic-resistant forms have been found.[3] Healing generally occurs without scarring.[7]
Impetigo affected about 140 million people (2% of the world population) in 2010.[6] It can occur at any age, but is most common in young children aged two to five.[3] In some places the condition is also known as "school sores".[1] Without treatment people typically get better within three weeks.[3] Recurring infections can occur due tocolonization of the nose by the bacteria.[8][9] Complications may includecellulitis orpoststreptococcal glomerulonephritis.[3] The name is from theLatinimpetere meaning "attack".[10]
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, leakingpus or fluid, and forms a honey-coloredscab,[11] followed by a red mark which often heals without leaving a scar. Sores are not painful, but they may be itchy.Lymph nodes in the affected area may be swollen, but fever is rare. Touching or scratching the sores may easily spread the infection to other parts of the body.[12]
Skin ulcers withredness and scarring also may result from scratching or abrading the skin.[citation needed]
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Bullous impetigo, mainly seen in children younger than two years, involves painless, fluid-filledblisters, 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.[12]
Ecthyma, the nonbullous form of impetigo, produces painful fluid- or pus-filled sores with redness of skin, usually on the arms and legs, becomeulcers that penetrate deeper into thedermis. After they break open, they form hard, thick, gray-yellow scabs, which sometimes leave scars. Ecthyma may be accompanied by swollenlymph nodes in the affected area.[12]
Impetigo is primarily caused byStaphylococcus aureus, and sometimes byStreptococcus pyogenes.[13] Bothbullous and nonbullous are primarily caused byS. aureus, withStreptococcusalso commonly being involved in the nonbullous form.[14]
Impetigo is more likely to infect children ages 2–5, especially those that attend school or day care.[3][15][1] 70% of cases are the nonbullous form and 30% are the bullous form.[3] Impetigo occurs more frequently among people who live in warm climates.[16]
Theinfection is spread by direct contact withlesions or withnasalcarriers. Theincubation period is 1–3 days after exposure toStreptococcus and 4–10 days forStaphylococcus.[17] Dried streptococci in the air are not infectious to intact skin. Scratching may spread the lesions.[citation needed]
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.[13] If a visual diagnosis is unclear a culture may be done to test for resistant bacteria.[18]
Other conditions that can result in symptoms similar to the common form includecontact dermatitis,herpes simplex virus,discoid lupus, andscabies.[3]
Other conditions that can result in symptoms similar to the blistering form include otherbullous skin diseases,burns, andnecrotizing fasciitis.[3]
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.[19] Children with impetigo can return to school 24 hours after starting antibiotic therapy as long as their draining lesions are covered.[20]
Antibiotics, either as a cream or by mouth, are usually prescribed. Mild cases may be treated withmupirocin ointments. In 95% of cases, a single seven-day antibiotic course results in resolution in children.[20][21] It has been advocated that topicalantiseptics are inferior to topical antibiotics, and therefore should not be used as a replacement.[3] However, theNational 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.[22] This recommendation is part of an effort to reduce the overuse of antimicrobials that may contribute to the development of resistant organisms[23] such asMRSA.
More severe cases require oral antibiotics, such asdicloxacillin,flucloxacillin, orerythromycin. Alternatively,amoxicillin combined withclavulanate potassium,cephalosporins (first-generation) and many others may also be used as an antibiotic treatment. Alternatives for people who are seriously allergic to penicillin or infections withmethicillin-resistantStaphococcus aureus includedoxycycline,clindamycin, andtrimethoprim-sulphamethoxazole, although doxycycline should not be used in children under the age of eight years old due to the risk of drug-inducedtooth discolouration.[20] When streptococci alone are the cause, penicillin is the drug of choice. When the condition presents withulcers,valacyclovir, an antiviral, may be given in case a viral infection is causing the ulcer.[24]
Without treatment, individuals with impetigo typically get better within three weeks.[3] Complications may includecellulitis orpoststreptococcal glomerulonephritis.[3]Rheumatic fever does not appear to be related.[3]
Globally, impetigo affects more than 162 million children in low- to middle-income countries.[25] The rates are highest in countries with low available resources and is especially prevalent in the region ofOceania.[25] Thetropical climate and high population in lower socioeconomic regions contribute to these high rates.[26] Children under the age of 4 in the United Kingdom are 2.8% more likely than average to contract impetigo; this decreases to 1.6% for children up to 15 years old.[27] As age increases, the rate of impetigo declines, but all ages are still susceptible.[26]
Impetigo was originally described and differentiated by the EnglishdermatologistWilliam Tilbury Fox around 1864.[28] The wordimpetigo is the genericLatin word for 'skin eruption', and it stems from the verbimpetere 'to attack' (as inimpetus).[29] Before the discovery of antibiotics, the disease was treated with an application of the antisepticgentian violet, which was an effective treatment.[30][31]
