Impetigo

For the band, see Impetigo (band).

Impetigo
A severe case of facial impetigo
Classification and external resources
Pronunciation	/ɪmpᵻˈtaɪɡoʊ/
Specialty	Dermatology, infectious disease
ICD-10	L01
ICD-9-CM	684
DiseasesDB	6753
MedlinePlus	000860
eMedicine	derm/195 emerg/283 med/1163 ped/1172
Patient UK	Impetigo
MeSH	D007169

Impetigo is a contagious bacterial skin infection most common among preschool children. People who play close contact sports, such as wrestling are also susceptible, regardless of age. Antibiotic creams or pills are often used as a remedy.

Globally impetigo affected about 140 million people (2% of the population) in 2010. Impetigo is not as common in adults. The name derives from the Latin impetere ("assail"). It is also known as school sores.

Classification

Impetigo on the neck

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 heals without leaving a scar. Sores are not painful, but 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. Ulcerations with erythema and scarring also may result from scratching or abrading of the skin.

Bullous impetigo

Bullous impetigo

Bullous impetigo, mainly seen in children younger than 2 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

In this form of impetigo, 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

It 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.

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.

Treatment

For generations, the disease was treated with an application of the antiseptic gentian violet. Today, topical or oral antibiotics are usually prescribed. Mild cases may be treated with bactericidal ointment, such as mupirocin.

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 MRSA include doxycycline, clindamycin, and SMX-TMP. When streptococci alone are the cause, penicillin is the drug of choice.

Epidemiology

Globally, impetigo affected about 140 million people (2% of the population) in 2010.

External links

• Impetigo at DMOZ
• Impetigo and Ecthyma at Merck Manual of Diagnosis and Therapy Professional Edition