An Overview of Erysipelas (St. Anthony's Fire)

Cousin of Cellulitis Causes by a Specific Bacteria

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Erysipelas is a bacterial infection of the skin outer's layers. In addition to causing pain, redness, and rash, erysipelas will usually be accompanied by fevers, chills, and malaise. Erysipelas is similar to cellulitis, another bacterial infection that involves deeper layers of skin. Although potentially serious, erysipelas can usually be treated with a course of antibiotics.

In addition to the skin, erysipelas can cause the swelling and blockage of the superficial vessels of the lymphatic system. The role of the lymphatic system is to collect and isolate disease-causing agents so that the immune system can neutralize them. In addition to the lymph vessels, the lymphatic system consists of lymph nodes and lymph fluid.

Erysipelas is referred to by some as St. Anthony's Fire, an apt description given the rash's fiery appearance.

Erysipelas was identified as 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.

Symptoms

Erysipelas is characterized by well-demarcated areas of bright red skin that are typically rough, raised and leathery. It mainly affects the face but can also involve the hands, arms, legs, or feet. The rash will have clearly defined borders with raised edges and a shiny, orange-peel-like texture. Warmth, pain, and swelliing are common features.

A range of symptoms typically precedes the appearance of the rash by anywhere from four to 48 hours. They may include:

  • Fever
  • Chills
  • Fatigue
  • Anorexia
  • Vomiting

The appearance of the rash is generally rapid and fast-spreading. The infection may extend beyond the superficial layers and cause the formation of tiny, fluid-filled blisters (vesicles) and pinpoint blood spots (petechiae). The lymph nodes nearest the infection may also become swollen, as can the skin overlying the lymph nodes.

Lymphedema is a common feature of erysipelas wherein the obstruction of the lymphatic system causes fluid to overload tissues, leading to swelling (edema) of a limb, neck, or face.

Complications

Erysipelas can cause the disruption of the skin's barrier function and allow the bacteria to enter the bloodstream through tiny cracks. In some cases, this can lead to a systemic bacterial infection, known as bacteremia. If this happens, the infection can disseminate (spread) and begin to affect joints, bones, the heart, and the brain.

If bacteremia persists, it can trigger a potentially deadly, whole-body inflammatory response known as sepsis (particularly in people with a weakened Immune system). Sepsis is characterized by fever, difficulty breathing, rapid heart rate, and mental confusion. In rare instances, it can lead to septic shock.

In rare cases, the dissemination of bacteria throughout the body can lead to endocarditis (a heart infection), septic arthritis, gangrene, and post-streptococcal glomerulonephritis (a kidney condition mainly affecting kids).

Causes

Erysipelas is caused by a specific type of bacteria known as Streptococcus pyogenes. In addition to erysipelas, Streptococcus pyogenes can also cause pharyngitis (sore throat) and strep throat. The face and hands are most commonly affected because a person with strep throat can cough and launch the virus onto the skin.

Erysipelas generally occurs when the bacterium enters a cut, abrasion, or other types of break in the skin. Once it enters, the bacteria can quickly multiply and spread via tiny lymph vessels situated just beneath the surface of the skin. In an attempt to neutralize the bacteria, the immune system will launch an inflammatory assault, causing local blood vessels to dilate and tissues to swell.

In some cases, the bacterium can penetrate uncompromised skin if there is pre-existing lymphedema (such as following a radical mastectomy where lymph nodes are removed). Without a lymphatic system to isolated disease-causing microorganisms, the skin is more vulnerable to local infections.

While lymphedema can increase the risk of erysipelas, erysipelas can also cause lymphedema, increasing the risk of reinfection and recurrence.

Risk Factors

Erysipelas is most commonly seen in the elderly and infants who have weaker immune systems and are less able to fight local infections. With that said, anyone can be affected, espeically those with certain risk factors. These include:

Diagnosis

As it is so distinctive, erysipelas can usually be diagnosed by the appearance of the rash alone. Skin biopsies and cultures generally do not help with the diagnosis. Certain blood tests, like a white blood cell (WBC) count and C-reactive protein (CRP), may be useful in detecting immune activation and inflammation, but they cannot diagnose erysipelas.

To make a definitive diagnosis of erysipelas, the doctor would need to exclude other possible causes. The differential diagnoses may include:

Erysipelas vs. Cellulitis

Cellulitis is very similar to erysipelas in that it can be caused by Streptococcus pyogenes (as well as other streptococcal and staphylococcal bacterium). However, there are key differences between the two skin infections.

Erysipelas affects the upper layers of the skin, whereas cellulitis affects deeper tissues. Because of this, erysipelas is more likely to form vesicles and release clear serous fluid, while cellulitis is more likely to form abscesses and release pus.

Cellulitis is typically slower to develop than erysipelas. With cellulitis, the affected skin is not nearly as red and rarely has well-defined borders. It is because erysipelas develops so quickly, overloading the skin will inflammation, that the fiery redness and demarcated rash occur.

Still, because there is much room for overlap, clinical judgment may be needed to differentiate between erysipelas and cellulitis.

Treatment

Erysipelas is standardly treated with antibiotics, the options of which include:

  • Penicillin
  • Cephalosporin-class antibiotics
  • Clindamycin (brand names Cleocin, Clindacin, Dalacin)
  • Dicloxacillin (brand names Dycill, Dynapen)
  • Erythromycin (brand names Erythrocin, E-Mycin, Ery-Tab)
  • Azithromycin (brand names Zithromax, AzaSite, Z-Pak)

Penicillin generally remains the first-line treatment option for streptococcal infections. Other antibiotics may be used if there is an allergy to penicillin.

Most cases can be treated with oral rather than intravenous (IV) antibiotics. Any pain, swelling, or discomfort can be treated with rest, a cold compress, and elevation of the affected limb. Nonsteroidal anti-inflammatory drugs like Advil (ibuprofen) or Aleve (naproxen) can be used to relieve pain and fever.

If the face is involved, chewing should be minimized to avoid pain. In some cases, a mechanical soft diet may be recommended during the healing phase.

Treatment is often monitored by marking the borders of the rash with a marker pen. Doing so can make it easier to see if the rash is receding and the antibiotics are working.

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

Even after the appropriate treatment, erysipelas can recur in 18% to 30% of cases, especially in those with a compromised immune system.

People with recurrent infections may need a prophylactic (preventive) dose of an antibiotic, taken daily, to prevent a recurrence.

A Word From Verywell

Erysipelas is a fairly common skin infection that, fortunately, is easily treated in most cases and rarely leads to complications. Still, if you have symptoms of erysipelas, you should call your doctor right away. Quick treatment prevents the worsening of your condition and helps ease discomfort.

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Article Sources

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