Erythrasma: What It Looks Like and How to Get Rid of It

Erythrasma is a superficial skin infection caused by a bacteria called Corynebacterium minutissimum. The infection causes a discolored patch, mainly in skin folds such as the armpits or groin.

There are two types:

• Interdigital erythrasma, which mainly develops between the toes
• Generalized erythrasma, which is more widespread and associated with immunosuppression

The rash itself is not serious but may be an early warning sign of a more serious condition. The treatment may involve improved hygiene and topical or oral antibiotics if the condition is severe.

This article describes the symptoms, cause, diagnosis, and treatment of erythrasma. It also offers tips on how to avoid this generally harmless skin infection.

What Does Erythrasma Look Like?

Erythrasma mainly occurs in so-called intertriginous areas of the body where two skin areas touch or rub together. These include the armpits, groin, navel, under the breasts, and between the toes. This is where moisture can become trapped, creating the ideal environment for bacterial growth.

Symptoms of erythrasma include:

• A slightly raised, pinkish patch that quickly darkens and turns scaly
• Mild itchiness
• Regular or irregular borders
• Fine scaling or flaking

Most people experience interdigital erythrasma, mainly in the webbing of the third, fourth, and fifth toes.

Generalized erythrasma is more widespread and will often move beyond intertriginous areas to the trunk and torso.

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While complications are rare, erythrasma can co-occur with contact dermatitis, a fungal skin infection, or an unrelated bacterial infection (such as a staph infection). In rare cases, the infection can spread to deeper tissues, causing an abscess (pocket of pus) or potentially serious skin infection known as cellulitis.

How Do You Get Erythrasma?

Erythrasma is caused specifically by C. minutissimum. This is a relatively harmless bacteria found on the skin that the immune system is usually able to control. However, under the right conditions, the bacteria can overgrow, particularly if there is excessive moisture and/or a person's immune system is impaired.

Risk factors for C. minutissimum overgrowth include:

• Living in a humid tropical or subtropical climate
• Poor hygiene
• Abnormal sweating (hyperhidrosis)
• Having obesity and/or heavy skin folds
• Older age (associated with lower immune function)
• Immunosuppressive disorders like HIV or type 2 diabetes
• Immunosuppressant drugs (including those used to prevent organ transplant rejection)
• Chemotherapy

People who live in shared living spaces (such as residential nursing homes, student dorms, and barracks) are also more likely to get erythrasma.

How Can You Tell if You Have Erythrasma?

Erythrasma can often be diagnosed by appearance alone. The characteristic brown patch with fine scaling distinguishes it from fungal infections like tinea cruris (jock itch) which are redder, have thicker edges, and heavier scaling or peeling.

If in doubt, your healthcare provider can use a specialized light, known as a Wood's lamp, to confirm the diagnosis. Under the ultraviolet light, the patch will turn a fluorescent coral-pink color.

A Wood's lamp can help differentiate erythrasma from other skin conditions:

• Microsporum fungal infections, such as ringworm, turn a dull blue under a Wood's lamp.
• Pseudomonas bacterial infections, such as hot tub folliculitis, turn green.
• Malassezia fungal infections, also associated with folliculitis, turn a bluish-white.
• Intertrigo rash, caused by skin-to-skin friction, also turns green.
• Inverse psoriasis, a type of psoriasis found in skin folds, turns more red.
• Tinea versicolor, a fungal infection, turns a copper-orange.

If the infection is severe or recurrent, a scraping of skin can be cultured in the lab to see if there are any co-existing fungal or bacterial infections.

Recurrent or widespread erythrasma may warrant a blood glucose test to check for type 2 diabetes or an HIV test to check for HIV.

How Do You Get Rid of Erythrasma?

Erythrasma is typically self-limiting and will often resolve on its own without treatment. If needed, washing with antibacterial soap can help bring the bacteria back under control.

If the infection is widespread, a topical antibiotic or microbicide can be prescribed, such as 2% clindamycin, Fucidin ointment (sodium fusidate), and Whitfield's ointment (benzoic acid plus salicylic acid). These medications are typically applied twice daily for one to two weeks. Side effects include rash, redness, drying, itching, and nausea.

Serious infections may require oral antibiotics like clarithromycin, erythromycin, tetracycline, or chloramphenicol. Treatment may only require a single dose (for clarithromycin) or up to five daily doses (for erythromycin). Side effects include rash, nausea, stomach ache, diarrhea, loss of appetite, and vomiting.

How to Prevent Erythrasma

Erythrasma is sometimes difficult to avoid if you live in a hot, humid climate. This is especially true if you work outdoors.

Even so, there are a few simple ways to avoid erythrasma and other opportunistic skin infections:

• Wash regularly with a mild antibacterial soap or cleanser, paying extra attention to the groin, armpits, toes, and other areas where moisture accumulates.
• Dry your skin thoroughly after bathing. Pay extra attention to your toes. If you can't reach your toes, you can dry them with a hairdryer on a low setting.
• Change into fresh socks every day.
• Check that your shoes are dry before putting them (or alternate shoes every day so they have a chance to dry).
• If you are prone to sweating, use an over-the-counter antiperspirant and foot product (like Gold Bond foot powder or ZeroSweat lotion).
• In hot temperatures, use a fan or air conditioner to keep you cool while sleeping.
• Weight loss should be explored if you are overweight.

If you have recurrent bouts of erythrasma, speak with your healthcare provider about a topical antifungal like Micotin (miconazole) which can help prevent recurrence without the risk of antibiotic resistance.

Summary

Erythrasma is a bacterial skin infection that causes darkened, itchy patches, mainly in skin folds. The infection is caused by a relatively harmless bacteria known as Corynebacterium minutissimum. People who live in hot, humid climates, have obesity, or are immunosuppressed are at greatest risk.

Erythrasma can usually be diagnosed by appearance alone, though a Wood's lamp can help differentiate C, minutissimum from other bacterial or fungal causes. Erythrasma can usually be cleared with improved hygiene. Severe cases may require topical or oral antibiotics.