Ecthyma is a skin infection similar to impetigo, but more deeply invasive. Usually caused by a streptococcus infection, ecthyma goes through the outer layer (epidermis) to the deeper layer (dermis) of skin, possibly causing scars.
Streptococcal and staphylococcal bacteria may cause skin infections at various levels and depths. Ecthyma is similar to impetigo, but causes deeper erosions of the skin. The infection may start at the site of a bug bite or scratch.
Ecthyma is the most serious form of impetigo. It occurs when the infection penetrates deep into the dermis, the skin's second layer, causing painful, itchy sores that develop into pus- or fluid-filled ulcers with hard grayish yellow crusts. The ulcers may cause permanent scarring. Lymph nodes in the affected area may swell.
Ecthyma lesion usually begins as a vesicle (small blister) or pustule on an inflamed area of skin. A hard crust that is harder and thicker than the crust of impetigo soon covers this. With difficulty, the crust can be removed to reveal an indurated ulcer that may be red, swollen and oozing with pus. Lesions may stay fixed in size and sometimes resolve spontaneously without treatment, or they may gradually enlarge to a sore of 0.5-3 cm in diameter. The areas most affected are the buttocks, thighs, legs, ankle and feet. Occasionally, the local lymph nodes become swollen and painful.
Untreated impetigo contagiosa can turn into ecthyma, which is most common among older adults, people with diabetes and people with compromised immune systems. CENTANY (mupirocin ointment), a topical antibiotic free of polyethylene glycol (PEG), can be used safely in patients with these conditions since there are no contraindications in renally impaired patients who may need to treat larger areas of skin. This condition is typically treated with oral antibiotics or a combination of oral and topical antibiotics.
Treatment depends on the extent and severity of infection. Any underlying disease or skin infection such as scabies or dermatitis should also be treated. Soak a clean cloth in a mixture of half a cup of white vinegar in a litre of tepid water. Apply the compress to moist areas for about ten minutes several times a day. Gently wipe off the crusts. A topical antibiotic ointment such as fucidic acid or mupirocin is often prescribed for localised ecthyma. A topical antiseptic such as povidone iodine, antibacterial Manuka honey or Crystacide (hydrogen peroxide) cream may be used instead. Apply it at least three times a day to the affected areas and surrounding skin. The treatment should be applied after removing crusts. Look carefully for new lesions to treat. Continue for several days after healing. Oral antibiotics are recommended if the infection is extensive or proving slow to respond to topical antibiotics. The preferred antibiotic is a penicillin, however the antibiotic chosen should be active against both Streptococcus pyogenes and Staphylococcus aureus (usually dicloxacillin or flucloxacillin). The duration of treatment varies; several weeks of therapy may be necessary to completely resolve ecthyma.