Impetigo

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 scab, 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. Skin ulcers with redness and scarring also may result from scratching or abrading the skin. Bullous impetigo after the bullae have broken Bullous impetigo, mainly seen in children younger than two years, involves painless, fluid-filled blisters, 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. 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 lymph nodes in the affected area. ==Causes==

Impetigo is primarily caused by Staphylococcus aureus, and sometimes by Streptococcus pyogenes. Both bullous and nonbullous are primarily caused by S. aureus, with Streptococcus also commonly being involved in the nonbullous form. Predisposing factors Impetigo is more likely to infect children ages 2–5, especially those that attend school or day care. 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 sebum and is often found on the arms, legs, or face. 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. Children with impetigo can return to school 24 hours after starting antibiotic therapy as long as their draining lesions are covered. ==Treatment==

Antibiotics, 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. It has been advocated that topical antiseptics are inferior to topical antibiotics, and therefore should not be used as a replacement. This recommendation is part of an effort to reduce the overuse of antimicrobials that may contribute to the development of resistant organisms such as MRSA. More severe cases require oral antibiotics, such as dicloxacillin, flucloxacillin, or erythromycin. Alternatively, amoxicillin combined with clavulanate 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 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. ==Epidemiology==

Globally, impetigo affects more than 162 million children in low- to middle-income countries. The tropical climate and high population in lower socioeconomic regions contribute to these high rates. 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. As age increases, the rate of impetigo declines, but all ages are still susceptible. ==History==

Impetigo was originally described and differentiated by the English dermatologist William Tilbury Fox around 1864. The word impetigo is the generic Latin word for 'skin eruption', and it stems from the verb 'to attack' (as in impetus). Before the discovery of antibiotics, the disease was treated with an application of the antiseptic gentian violet, which was an effective treatment. == References ==