What Is the Erythrasma Skin Infection?

Discover the Cause of Erythrasma, How to Spot It, and How It's Treated

Erythrasma is an infection that's caused by the bacteria Corynebacterium minutissimum. It generally strikes the area between the third and fourth toes, but it can also be found in the groin region, in the armpits, and under the breasts—moist areas where there tend to be skin folds. Erythrasma is more common in the elderly, people who are overweight, people with diabetes and people who live in warm.

moist climates.

What Erythrasma Looks and Feels Like

Erythrasma starts as a patch that's pink or red in color and has well-defined edges. This patch has a finely wrinkled appearance and a very fine scale on top. Over time, the rash fades to brown. This consistent brown color with the fine scale distinguishes it from jock itch and other fungal infections, which are typically redder around the edges and have thicker scaling on the edges. The patch may also itch a little.

Other Rashes That May Look Like Erythrasma

As mentioned earlier, jock itch is sometimes confused with erythrasma. Other skin conditions that can look similar include:

How Erythrasma Is Diagnosed

Now and then, a physician can diagnose erythrasma based solely on its appearance. But more often, a doctor will need to perform other tests to be sure. The best way for a doctor to tell the difference between erythrasma and a fungal infection is to do something called a Wood's lamp examination on the rash.

Under the UV light of a Wood's lamp, erythrasma turns a bright coral red, but fungal infections do not. Other tests that may assist in diagnosis include:

  • Gram Stain: This is a way to identify bacteria by looking at a sample of the scale. 
  • KOH Test: This is a test that's used to identify fungi. 
  • Skin Biopsy: This removes a sample of tissue so it may be examined under a microscope. If there are bacteria present, they will be located in the specimen's upper layer. 

    How Erythrasma Is Treated

    Since it is a bacterial infection, erythrasma is best treated with antibiotics, and, fortunately, several antibiotics fit the bill. A doctor may start you with an antibacterial soap or gel to put directly onto the skin area, but if a case is particularly severe, an oral antibiotic (taking a pill by mouth) may be necessary. Treatment should eliminate the rash, but it's possible for it to recur. The following are antibiotics that are typically prescribed for erythrasma:

    • Topical antibiotics like clindamycin or erythromycin, twice a day for two weeks
    • Erythromycin: 250 milligrams four times a day for five days
    • Clarithromycin: 1 gram single dose

    How to Help Prevent Erythrasma

    To reduce your risk of developing erythrasma, try to maintain a healthy weight, shower frequently and then fully dry your skin, and avoid hot temperatures and damp locations when possible.

    Sources:

    Blaise, G et al. "Corynebacterium-associated skin infections." International Journal of Dermatology. 47(2008): 884-90.

    Habif, Thomas. "Bacterial Infections." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 236-62.

    Continue Reading