Impetigo contagiosa is a highly contagious superficial skin infection caused by the bacteria staphylococcus aureus or the beta-hemolytic streptococci. Impetigo usually affects infants and young children.
What is the Cause of Impetigo Contagiosa?
Staphylococcus aureus is the commonest cause of non-bullous impetigo in developed countries, while the group A beta-hemolytic streptococci are more commonly associated with the disease in developing countries.
Primary infection with these organisms occurs in infancy or early childhood. Secondary infection on previously existing abrasions or wounds can occur at any age. Both genders are equally affected in impetigo contagiosa.
What are the Predisposing (Risk) Factors in Impetigo Contagiosa?
Impetigo is more common in warm, humid climates. Exposure to dust, poor personal and environmental hygiene, low nutritious status, crowded living conditions, neglected skin wounds and insect bites etc are the main risk factors for contracting impetigo contagiosa and other bacterial skin infections.
Certain skin diseases like the herpes simplex (cold sores), chickenpox, ring worms etc., which breach the protective skin barrier, can predispose the skin to secondary impetiginisation with staph or streptococci.
What are the Presenting Signs and Symptoms of Impetigo Contagiosa?
Impetigo contagiosa starts as a minute red spot which evolves into a small blister with a very thin roof within a few hours. A group of such minute blisters may appear in the vicinity and soon rupture to form a skin rash with a red, moist base. The serous and pustular discharge produced by the infection dries up to form the typical honey colored, adherent (stuck on) crusts of the impetigo contagiosa.
Removing the crust reveals a raw, red erosion on the skin surface, which quickly gets covered with a yellowish brown serous, purulent discharge.
Untreated, similar satellite skin rashes appear in the vicinity of the initial lesion and elsewhere on the body. The face, especially near the nose, mouth and chin, are the most commonly affected sites in impetigo. Hands, feet and legs are the other common sites involved
The impetigo rashes may be accompanied by itching or burning pain in the initial stages.
What are the Complications of Impetigo Contagiosa?
With early treatment, the skin rashes heal without leaving any marks or scars. Antibodies formed against the bacteria can rarely cause blockage and inflammation of the filtering mechanism in the kidneys leading to the dreaded complication of glomerulonephritis.
Whether early treatment prevents the occurrence of glomerulonephritis is still a controversial issue. In developing countries, where the treatment is delayed or alternative therapies are resorted to, the incidence of glomerulonephritis is high among the impetigo-affected children. Most dermatologists consider this as an indication for the institution of appropriate antibiotics in the early stage of the disease.
Other possible complications include cellulitis, spread of the infection through blood stream or lymphatic vessels, sepsis, scarlet fever and eruption of guttate psoriasis.
What are the Other Skin Diseases that may Resemble Impetigo Contagiosa?
Folliculitis, the inflammation of hair follicles, when involving a group of follicles and the surrounding skin surface can mimic impetigo. Secondary infected insect bite rashes can resemble impetigo. Scabies with secondary infection is commonly mistaken for impetigo, especially on the hands and wrists. Severe lice infestation on the scalp can lead to secondary bacterial infection on the scalp, face, neck and upper extremities.
Impetiginized ring worm infestations, infected eczematous reactions and contact dermatitis are some of the other diseases that have to be ruled out before making a diagnosis of impetigo contagiosa.
Cold sores and localized shingles, following secondary bacterial infection, at times, resemble impetigo rashes.
How is Impetigo Contagiosa Diagnosed?
Usually the clinical picture of the typical honey-colored crusted rashes on the exposed areas of the body in children is sufficient to make a diagnosis of the impetigo. Gram stained smears and culture of the pus will help in identifying the causative organism.
Culture and sensitivity studies are particularly useful in identifying and treating MRSA, the methicillin resistant Staph aureus, infection.
Recurrent attacks of impetigo calls for detailed laboratory investigations to rule out underlying systemic diseases which could be lowering the body’s immunity against the invading organisms.
How to Treat the Skin Infection Impetigo Contagiosa?
General measures in treating impetigo include keeping the child clean and dry. Cleansing with antiseptic solutions twice daily will avoid spread to other areas. A balanced, nutritious diet will help in faster recovery from the infection. Utensils and bath towels should not be shared with other children.
Topical mupirocin ointment is most often sufficient to get rid of the localised impetigo rashes. It has to be applied twice daily for five to seven days. For generalized impetigo contagiosa, antibiotics like erythromycin, clarithromycin, azithromycin, amoxicillin with clavulenic acid, cloxacillin and cephalexin are useful in appropriate doses. Resistant cases caused by the MRSA are managed by medications like vancomycin, dicloxacillin and clindamycin.
With suitable treatment, impetigo clears up within five to seven days. Recurrent impetigo calls for treatment of the carrier state, the nasal opening and the perianal region being the most common sites where the staph could reside. Daily application of mupirocin ointment to these areas for a couple of weeks could get rid of recurrent impetigo infections.
Related Articles
Sources:
- Craft N et al. Superficial Cutaneous Infections and Pyodermas. Fitzpatrick’s Dermatology in General Medicine. Seventh Edition. 2008; 2:1694-1709. McGraw Hill.
- Rook’s Textbook of Dermatology, 7th Edition, 2004
Disclaimer:
The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, Dr.Hanish Babu, MD or Suite101 will not be responsible for any consequences. The images provided are for illustration purpose only.
Hanish Babu - Dr.Hanish Babu, MD is a dermatologist and a feature writer on Suite101.com with more than 200 articles related to skin diseases on the ...
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