Characteristic yellow crusted lesions which are most commonly found on the face, typically there are also scattered surrounding lesions called satellite lesions. This starts out as vesicular lesions that are rarely painful. A less common form is bullous impetigo which is presented by larger blisters occurring on the trunk or diaper area of children. Ecthyma is more serious form of impetigo that penetrates deeply into skin causing painful collection of fluid or pus filled sores that turn into deep ulcers.

Diagnosis is mainly by clinical examination by a dermatologist. Assays of streptococcal antibodies are of no value in the diagnosis and treatment of impetigo, but they provide helpful supporting evidence of recent streptococcal infection in patients suspected of having post-streptococcal glomerulonephritis. The anti-streptolysin O response is weak in patients with streptococcal impetigo, presumably because skin lipids suppress streptolysin O response, but anti-DNAase B levels are consistently elevated.

Generally, the clinical course and treatment of impetigo depends on many factors including number of lesions, location of lesions, and the urgent need to limit spread of infection to other households or other persons in contact. If the case is presented only by small localized lesions, topical antibacterials like hydrogen peroxide and mupirocin ointments may be used for up to two weeks. In patients who do not respond to topical therapy, or those with impetigous lesions spreading in larger areas, lymphoedematous conditions or systemic illness oral antibiotics may be used like oral Flucloxacillin 500 mg four times daily for 7 days.

Other alternatives include Cephalexin 25 mg/kg/day in 4 divided doses for childeren. If patient is allergic to penicillins Erythromycin (which was in past the mainstay of pyoderma treatment) may be used. Clindamycin is generally effective treatment for skin bacterial infections including impetigo. If there is no response to treatment, courses of topical antibiotics should not be repeated. Instead, swabs to exclude resistant organisms should be done and proper therapy for underlying sensitive strains considered [9]. In severe cases, intravenous antibiotics may be used to treat and control the spread of impetigo [10].

Impetigo may be self-limiting within two to three weeks, but antibiotics can shorten the course of the disease and help prevent the spread to others [7]. Superficial crusts and blisters of impetigo usually do not leave scars. Red skin lesions last for weeks, but redness fades within days to weeks.

Suppurative lesions from streptococcal impetigo are not a common complication. One potentially serious, but rare (only in 1% of cases) complication of impetigo caused by streptococcus bacteria is acute glomerulonephritis and rheumatic fever [8]. The ulcerative scarring which is associated with a deeper and more serious form of impetigo (e.g. ecthyma) can leave permanent scars.

It is commonly caused by beta hemolytic streptococci and/or Staphylococcus aureus. These are the usual microorganisms that colonize the unbroken skin. These gram positive strains are often times easily treatable, but impetigo may also be caused by methicillin-resistant and gentamycin-resistant strains of Staphylococcus aureus [3].

Impetigo is common through the world but it is most frequent among children in the lower economic strata in tropical or subtropical regions. The disorder is also seen to be prevalent in northern regions during the summer and fall months [4]. Its peak incidence is among children with age two to five years, although older children and adults may also be afflicted. There is no sex predilection, and all races are susceptible. Impetigo infections are more common in summer. Participation in sports that involve skin to skin contact, such as football and wrestling increases your risk of developing impetigo. The causative bacteria often enter the skin through a small skin injury, insect bites or rash. The international mean incidence of impetigo is 10-22 cases per 1000 population per year depending on the geographic location [5]. Older adults and people with diabetes or a compromised immune system are more likely to develop ecthyma which is a deeper and more serious form of impetigo that usually leaves scars.

Research studies of streptococcal impetigo have elucidated that the causative microorganisms initially colonize the intact skin; thus, proper personal hygiene can directly subdue the disease incidence. Inoculation of surface organisms into the skin by abrasions, minor trauma, or insect bites (pediculosis) then ensues [6]. During the course of two to three weeks, streptococcal strains may be transferred from the skin and impetigo lesions to the upper respiratory tract. In contrast, in patients with staphylococcal impetigo, the pathogens are usually present in the nose before causing cutaneous disease.

Bullous impetigo is caused by strains of Staphylococcus aureus that produce a toxin causing cleavage in the superficial layers of skin. In past, non bullous lesions were usually caused by streptococci. Now, most cases of impetigo are caused by staphylococci alone or in combination with streptococci. Streptococci isolated from lesions are primarily group A organisms, but occasionally, other serogroups (such as C and G) are responsible.

Wash your hands or hands of your child after touching patches of impetigo. Usage of towels, flannels, and other fomites should be personal until the infection is eradicated. Children with impetigo should stay off school until there is no crusting.

Impetigo is considered the most common bacterial skin infection in children. It may appear primarily or may occur as a secondary bacterial infection on abrasions and lacerations of the skin [1]. Impetigo usually resolves in 2-3 weeks but the use of antibiotics can shorten its course and prevent it from spreading. It may occur as bullous and non-bullous forms and 70% of these cases are in non-bullous forms especially in the pediatric age group [2].

Definition

Impetigo is a benign and highly contagious skin infection affecting epidermis appearing everywhere on the body, but usually occurs in exposed areas like the nose, mouth, arms, and legs.

Cause

Impetigo is caused by Staphylococcus aureus and Beta hemolytic Streptococcus. 

Symptoms

Non-tender vesicular lesions that progresses to crusting lesions that’s spreads in the epidermis are the typical symptom.

Diagnosis

Diagnosis is by mean of direct physical examination of the skin surface.

Treatment and follow-up

Topical hydrogen peroxide, mupirocin, clindamycin and bacitracin. Intravenous and oral antibiotics may be taken to prevent the aggressive spread of the infection.

1. Moulin F, Quinet B, Raymond J, Gillet Y, Cohen R. [Managing children skin and soft tissue infections]. Arch Pediatr. Oct 2008; 15 Suppl 2:S62-7.
2. Cole C, Gazewood J. Diagnosis and treatment of impetigo. Am Fam Physician. Mar 15 2007; 75(6):859-64.
3. Kuniyuki S, Nakano K, Maekawa N, Suzuki S. Topical antibiotic treatment of impetigo with tetracycline. J Dermatol. Oct 2005; 32(10):788-92.
4. Loffeld A, Davies P, Lewis A, Moss C. Seasonal occurrence of impetigo: a retrospective 8-year review (1996-2003). Clin Exp Dermatol. Sep 2005; 30(5):512-4.
5. Razmjou RG, Willemsen SP, Koning S, et al. Determinants of regional differences in the incidence of impetigo. Environ Res. Jul 2009; 109(5):590-3.
6. Treating impetigo in primary care. Drug Ther Bull. Jan 2007; 45(1):2-4.
7. Patrizi A, Raone B, Savoia F, Ricci G, Neri I. Recurrent toxin-mediated perineal erythema: eleven pediatric cases. Arch Dermatol. Feb 2008; 144(2):239-43.
8. Parks T, Smeesters PR, Steer AC. Streptococcal skin infection and rheumatic heart disease. Curr Opin Infect Dis. Apr 2012; 25(2):145-53.
9. Bernard P. Management of common bacterial infections of the skin. Curr Opin Infect Dis. Apr 2008; 21(2):122-8.
10. American Academy of Pediatrics. Group A Streptococcal infections. In: Pickering LK, ed. Red Book: 2012 Report of the Committee on Infectious Diseases. 29th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2012:668-680.