Erysipelas, also called St. Anthony's fire, is caused by infection by Group A Streptococci. This same type of bacteria is responsible for such infections as strep throat, and infections of both surgical and other kinds of wounds in the skin. The infection occurs most often in young infants and the elderly. Erysipelas is a form of cellulitis, a bacterial infection affecting the most superficial layers of the skin. It particularly affects infants and the elderly, but can affect any age group. Risk factors are similar to those for other forms of cellulitis. Unlike cellulitis, almost all erysipelas is caused by Group A beta haemolytic
streptococci (Streptococcus pyogenes). Erysipelas usually occurs rather abruptly. When the preceding infection was strep throat, the rash begins on the face. Occasionally, when the preceding infection was of a wound from an injury or operation, the rash will appear on an arm or leg.
Classically, the usual presentation is a bright-red, butterfly-shaped rash appearing across the bridge of the nose and the cheeks. It is hot to the touch, painful, shiny, and swollen, with clearly defined margins. The edges of the rash are a raised ridge, hard to the touch. There may be fluid-filled bumps scattered along the area. The rash spreads rapidly. Some patients have swelling of the eyelids, sometimes so severe that their eyes swell shut. The patient may have fever, chills, loss of energy, nausea and vomiting, and swollen, tender lymph nodes. In severe cases, walled-off areas of pus (abscesses) may develop beneath the skin. If left untreated, the streptococcal bacteria may begin circulating in the bloodstream (a condition called bacteremia). A patient may then develop an overwhelming, systemic infection called sepsis, with a high risk of death.
The symptoms of erysipelas usually arise quite suddenly. A small red area appears on the skin. Within a few hours it expands markedly. The infection spreads like a wave beneath the skin, creating a raised border between the infected area and the surrounding, healthy skin. Erysipelas predominantly affects the skin of the lower limbs, but when it involves the face it can have a characteristic butterfly distribution on the cheeks and bridge of the nose. Symptoms and signs of erysipelas are usually abrupt in onset and often accompanied by general illness in the form of fevers, chills and shivering. Affected skin is distinguished from other forms of cellulitis by a well-defined, raised border. The affected skin is red, swollen and may be finely dimpled (like an orange skin). Cellulitis does not usually exhibit such marked swelling but shares other features with erysipelas such as pain and increased warmth of affected skin. The less dense tissue underneath the skin (fat tissue) is particularly prone to infection. In the facial area, the inflamed spot is typically found on the cheeks and around the eyes and ears. The development of the infection is accompanied by chills, high fever and headaches. Without effective antibacterial treatment, the patient may feel quite unwell.
Penicillin is the drug of choice for treating erysipelas. It can usually be given by mouth, although in severe cases (or in cases of diagnosed bacteremia) it may be given through a needle placed in a vein (intravenously). Even with antibiotic treatment, swelling may continue to spread. Other symptoms, such as fever, pain, and redness, usually decrease rapidly after penicillin is started. Cold packs and pain relievers may help decrease discomfort. Within about 5–10 days, the affected skin may begin drying up and flaking off.