Understanding Erysipelas (St. Anthony's Fire)

Bacterial Infection Aptly Named for Its Fiery Appearance

Sick woman taking her temperature
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Erysipelas is a bacterial infection of the skin that typically involves the lymphatic system. Erysipelas is also known as St. Anthony's Fire, an accurate description given the rash's fiery intensity.

Prior to the introduction of antibiotics, erysipelas was a much-feared disease, especially in infants. It was identified far back as the 11th century, where it and a cluster of other diseases were collectively named after Saint Anthony, the patron saint of lost causes.

Causes of Erysipelas

Erysipelas is most often caused by a specific type of bacteria known as group A Streptococcus. It can be caused less commonly by other types of streptococcus or staphylococcus bacteria.

Some cases of erysipelas are associated with skin injury, such by an abrasion, cut, or trauma that allows the infection to develop. However, most cases of erysipelas start on intact skin and on parts of the body where the lymphatic system is obstructed.

Appearance of Erysipelas

Erysipelas used to be found primarily on the face. However, it is now being seen commonly on the lower extremities.  This is due to the prevalence of group A Streptococcus as opposed to the type that causes facial infection (Streptococcus pyogenes).

A range of symptoms typically precede the appearance of rash by anywhere from four to 48 hours and can include:

  • fever
  • chills
  • fatigue
  • anorexia
  • vomiting

The rash will appear soon after as a red, hot, swollen, shiny patch.

It has clearly defined borders and has a textural consistency similar to that of an orange peel (which we refer to as "peau d'orange").

Diagnosis of Erysipelas

Erysipelas is diagnosed mainly by the appearance of the rash. Blood tests and skin biopsies generally do not help with the diagnosis.

In the past, saline solution was sometimes injected into the edge of the rash, drawn (aspired) back out, and cultured for bacteria.

This method is not used anymore as most tests are either inconclusive or result in a false negative analysis.

If the symptoms are severe enough, blood may be drawn and cultured for bacteria to rule out sepsis (a potentially life-threatening event wherein the body’s response to infection causes damage to its own tissues and organs).

Treatment of Erysipelas

Erysipelas is treated with antibiotics, which may include penicillin, dicloxacillin, cephalosporins, clindamycin, or erythromycin. Most can be treated with oral rather than intravenous (IV) antibiotics. Any pain or discomfort can often be treated with rest, a cold compress, and elevation of the affected extremity.

However, in cases of sepsis (or where infections do not improve with oral antibiotics), IV therapy may be prescribed under hospitalization.

Even after the appropriate treatment of infection, erysipelas can recur in 18 to 30 percent of cases. People who are especially susceptible to recurrence include those with a compromised immune or lymphatic system.

Because erysipelas is known the damage the lymphatic system (the system which transports immune cell through the body), the infection itself can increase the risk of recurrence.

People with recurrent infections may need to be treated with a daily course of low-dose antibiotics.

Source

  • Kirmani, N.; Woeltje, K.; and Babcock, H. The Washington Manual of Infectious Disease Subspecialty Consult. Lippincott Williams & Wilkins Publishers; 2012; ISBN 9781451113648.

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