Overview

Erythrasma is a common, superficial bacterial skin infection that primarily affects the skin folds, such as the groin, armpits, and under the breasts. It is caused by the bacterium Corynebacterium minutissimum and is characterized by reddish-brown, scaly patches that may be slightly itchy. Erythrasma is more common in adults, especially in warm, humid climates, and among individuals with certain risk factors like obesity and diabetes. Although it can resemble fungal infections, erythrasma is bacterial and responds well to antibiotic treatment.

Causes

The primary cause of erythrasma is the overgrowth of the bacterium Corynebacterium minutissimum, which normally lives harmlessly on human skin. Several factors can trigger or contribute to its overgrowth:

• Warm and humid environments: Excessive heat and moisture encourage bacterial growth, making erythrasma more prevalent in tropical and subtropical regions.
• Poor hygiene: Infrequent washing and excessive sweating can promote the development of erythrasma.
• Obesity: Skin folds in overweight individuals create ideal environments for bacterial overgrowth.
• Diabetes: People with diabetes are more susceptible due to immune system changes and increased skin moisture.
• Tight clothing: Wearing tight or non-breathable fabrics can trap heat and moisture against the skin.
• Age: It is more common in adults than in children.

Symptoms

Erythrasma presents with distinctive features, especially in skin folds. Common symptoms include:

• Reddish-brown patches: Flat or slightly raised patches with a red or brown color, often with well-defined borders.
• Scaly appearance: The affected skin may be dry or finely scaly.
• Itching: Mild itchiness is common, though some individuals may be asymptomatic.
• No pain: Erythrasma usually does not cause pain, unlike fungal infections which may cause irritation or burning.
• Localized to folds: Commonly affects the inner thighs, groin, armpits, under breasts, and between toes.
• Possible odor: In some cases, a mild, unpleasant odor may be present.

Diagnosis

Diagnosis of erythrasma is straightforward and often made by clinical examination, supported by specific diagnostic tools:

• Physical examination: A doctor examines the skin for typical color, location, and scaling patterns.
• Wood’s lamp test: Under ultraviolet light, erythrasma fluoresces with a distinctive coral-red color due to porphyrins produced by the bacteria.
• Skin scraping: Rarely, a skin scraping may be examined under a microscope to rule out fungal infections.
• Bacterial culture: In uncertain cases, a skin swab may be cultured to confirm the presence of Corynebacterium minutissimum.

Treatment

Erythrasma is easily treatable with a variety of approaches aimed at eliminating the bacteria and managing symptoms:

• Topical antibiotics: First-line treatment typically involves topical antibiotic creams or ointments like clindamycin or erythromycin.
• Antibacterial washes: Antibacterial soaps or washes containing benzoyl peroxide can help clear the infection and prevent recurrences.
• Oral antibiotics: In more extensive or resistant cases, oral antibiotics such as erythromycin or clarithromycin may be prescribed.
• Hygiene improvements: Regular cleansing of the affected area and maintaining dryness are important preventive measures.
• Weight management: Losing weight may reduce recurrence in obese individuals by decreasing skin folds.

Prognosis

The prognosis for erythrasma is excellent with appropriate treatment:

• Quick response to treatment: Most cases resolve within one to two weeks of proper antibiotic therapy.
• Low risk of complications: Complications are rare, though untreated cases can persist or spread.
• Risk of recurrence: Erythrasma can recur, especially in individuals with risk factors such as obesity, diabetes, or high sweating.
• Preventable condition: Good hygiene, maintaining a healthy weight, and keeping skin folds dry can significantly reduce the risk of recurrence.

With timely diagnosis and treatment, erythrasma is a minor and manageable skin condition with minimal long-term effects.