Impetigo overview On the Web
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Impetigo is a contagious superficial, bacterial skin infection most common among children age 2–6 years. People who play close contact sports such as rugby, American football and wrestling are also susceptible, regardless of age. The name derives from the Latin impetere ("assail"). It is also known as school sores. Skin is normally colonized with a large number of pathogens. When the pathogens increase in number on the skin or when there is a break in the continuity ofthe skin, they can lead to an infection.
In 1880, Alexander Ogston for the first time wrote about the involvement of Staphylococci in skin infections.In 1863, R. W. Dunn of Porrigo described lesions of impetigo as dirty, flat, irregular spots that are straw coloured. The first epidemic in the nurseries was reported in 1989.
Impetigo can be classified in various ways. It can be classified as bullous, non-bullous and ecthyma. It can also be classified as primary or secondary to a disease or process. Another classification pattern is with respect to the involved pathogen as staphylococcal or streptococcal impetigo. Non-bullous impetigo also known as "impetigo contagiosa" is caused by both Staphylococci and Streptococci and is estimated to make almost 70% of its cases.
Impetigo is spread by direct lesion contact. The incubation period is 1–3 days and 4-10 days for for Streptococci and Staphylococci respectively. Bullous impetigo is caused by exfoliative toxins which are released by Stapphylococcus aureus. The toxins are of two types, A and B, and lead to the production of bullae in the superficial layer of epidermis.
Impetigo is usually caused by Staphylococcus aureus. Streptococci (e.g. Streptococcus pyogenes) have been associated with the non-bullous form of impetigo and ecthyma.Streptococci can either infect individually or co-infect with Staphylococcus aureus. Non-bullous impetigo makes 70% of all the caess of impetigo.
Differentiating Impetigo from other Diseases
Impetigo must be differentiated from other diseases that cause pustules surrounded by erythematous skin, including chickenpox, herpes zoster, erythema multiforme, among others. It should be differentiated from scabies, contact dermatitis, lupus (discoid type), herpes simplex, burns, necrotizing faciitis.
Epidemiology and Demographics
Impetigo is often associated with insect bites, cuts, and other forms of trauma to the skin. Humidity, obesity, corticosteroid use, chemotherapy, dysglobulinemias, leukemias and malnutrition are some other risk factors for impetigo. Handwashing decreseas the incidence of impetigo by 34%.
The United States Preventive Services Task Force (USPSTF) has not issued any guidelines for the screening of impetigo.
Natural History, Complications and Prognosis
History and Symptoms
PImptigo has a conatgious course. People who suffer from cold sores have shown higher chances of suffering from impetigo. Patients with impetigo usualy have a history of recurrent lesions, immunodeficiency and trauma or abrasions. Symptoms may vary from vesicles to bullae that can be seen localized in early disease or spread to trunk and extremities if not taken care of. Fever and fatigue are important symtoms associated with seeking medical attention.
Patients may present with one or more pimple-like lesions surrounded by reddened skin. Lesions fill with pus, then break down over 4–6 days and form a thick crust. Impetigo is often associated with insect bites, cuts, and other forms of trauma to the skin. Itching is common.
The diagnosis of impetigo is primarily clinical. A thorough physical examination plays an important role in the diagnosis of impetigo along with a detailed history taking.Bullae, papules, pustules or ulcers may be visible depicting various types of impetigo.
Impetigo is primarily diagnosed clinically. Some laboratory tests can also be used to confirm the involved pathogen and to focus the treatment on that pathogen in particular. These include gram stain and culture and senstivity.
Xrays do not contribute in the diagnosis of impetigo.
CT scan does not contribute in the diagnosis of impetigo.
MRI does not contribute in the diagnosis of impetigo.
Ultrasound does not contribute in the diagnosis of impetigo.
Other Imaging Findings
Other imaging findings do not contribute in the diagnosis of impetigo.
Other Diagnostic Studies
Immunodeficiency can be evaluated in case of recurrence of impetigo. Other aspects may involve a detailed review of conditions like malnutrition, leukemia and diabetes.
The treatment of impetigo is primarily medical.
The mainstay of therapy for impetigo is antimicrobial therapy. Empiric therapy for mild disease includes either Mupirocin or Retapamulin applied topically. Empiric therapy for numerous lesions or poststreptococcoal glomerulonephritis includes either Dicloxacillin, Amoxicillin-Clavulanate, or Cephalexin. Penicillin is the drug of choice for impetigo caused by Streptococcus. Patients with impetigo caused by Methicillin-resistant Staphylococcus aureus are treated with either Doxycycline, Clindamycin, or Sulfamethoxazole-Trimethoprim. Non-bullous impetigo is self resolving and usually takes 1-2 weeks.Topical or oral antibiotics are usually prescribed.
Medical therapy is the primary mode of treatment for impetigo. Surgery is not usually required. Biopsy may sometimes be required if there is recurrence of lesions and the diagnosis of impetigo is not confimed.
Primary prevention of impetigo involves various aspect of ensuring hygiene including avoiding prolonged exposures to dirty environments , handwashing and regular bathing. Handwashing alone can decrease the incidence of impetigo by 34%.
The measure for secondary prevention of impetigo include avoidance of scratching, keeping the lesions covered, nails must be cut to avoid spread and keepig towel separate is also recommended.
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