Erythrasma - Causes, Symptoms, Diagnosis, and Treatment

What Is Erythrasma?

Erythrasma is a chronic superficial skin infection borne out of a bacterial origin. First described in 1859, the discoverer Burchardt hypothesized a fungal origin. It was pinned with actual etiology and anointed the name by Von Barensprung three years later in 1862, along with naming the bacterium. The manifestations are usually seen within folds of the skin, like under the arms, in the groin, and between the toes.

Who Is Susceptible to Erythrasma?

The reported incidence of erythrasma is about four percent. Globally found, but the incidences are more concentrated in the subtropical and tropical regions of the world. The prevalence is seen highest among college students residing in dormitories, barrack-posted soldiers, and senior homes.

The reported incidences increase with progressing age, but all ages are susceptible to the infection, with the youngest case being as young as one year infant. According to some studies conducted in the Middle East, erythrasma rates were as high as 46.7 percent, presenting as lesions between the toes. They accounted for about 35 percent of superficial skin folding infections, ranking second after dermatophytosis. The toe-web space incidences were followed by the groin and axillary vaults. The involvement of palm is a rare and unique occurrence.

The reported incidences were higher in black individuals. Although there is no overall gender predilection, men were more affected by the crural form of erythrasma, where interdigital erythrasma is 83 percent more likely to occur in women than in men. The studies also reported an association with body weight, with more than 62 percent of the caseload being prevalent in individuals with BMI (body mass index) greater than 23 and 50 percent of patients with a history of diabetes.

What Are the Types of Erythrasma?

Erythrasma can be categorized into three types:

• Interdigital Erythrasma: This mostly occurs in the toe webs, especially between the last two toes. This bacterial infection may be accompanied by a dermatophyte or candida fungal infection. The lesion leads to maceration and scaling with no major symptoms, just itching. Assessment of co-existing infection is done by s KOH (potassium hydroxide) preparation.

• Intertriginous Erythrasma: This type affects regions of friction like the armpit, groin, under breasts, buttocks crease, belly button, or thighs. This can occur in regions of folds of excess fat on the stomach, legs, or regions of skin chaffing. Most commonly seen in the diabetic population and may be asymptomatic or mild itching. The lesions show up as patches or plaques and result in a “cigarette paper” like appearance with fine scales.

• Disciform Erythrasma: Also known as “generalized erythrasma,” this is the most uncommon variant of the three and can affect any body part. Often seen in black women living in tropical climates and is characterized by well-defined scaly plaques over the trunk and proximal parts of the appendages. These lesions glow coral-red fluorescent under Wood’s lamp illumination.

What Causes Erythrasma?

Erythrasma is caused due to infection of Corynebacterium minutissimum bacteria. This is a gram-positive, catalase-positive, and non-sporing bacterium. The bacteria onsets erythrasma in individuals living in humid conditions, having excessive sweating, diabetes, poor hygiene, advanced age, coexisting skin conditions, and obesity. Under favorable conditions, the bacteria flourish in the upper levels of the stratum corneum, producing coral-red fluorescence under Wood’s light examination due to the presence of coproporphyrin III.

What Are the Clinical Features of Erythrasma?

Cutaneous changes are the most characteristic and observable clinical signs of erythrasma. The skin can have:

• Red patchy regions.

• Pink patchy regions.

• Brown, patchy regions.

• Scaly appearance.

• Cracked skin (especially on the feet).

• Softened or macerated skin.

• Wrinkly skin.

• Darker skin can have “loss-of-color” patches with darker edges.

• Burning sensation.

• Itching.

How to Diagnose Erythrasma?

A proper medication history, clinician’s observation, and presenting skin symptoms are sufficient to establish a differential. This can be followed by evaluation studies. First, the lesion can be observed under Wood’s light. Positive cases have lesions that glow up coral-red due to the presence of coproporphyrin III produced by the bacteria.

Rarely, biopsy studies may be indicated. Visualization is difficult with hematoxylin and eosin staining, so Periodic Acid-Schiff and Giemsa stains are indicated. Microscopic examination can show rod-like organisms in the horny layer of the skin. The organisms may be coccoid and the layer may be hyperkeratotic with some degree of lymphohistiocytic infiltration around the vessels of the superficial skin later. Gram-staining turns positive but is not acid-fast and produces dextrose, sucrose, and maltose, but not lactose. In-vitro, the organism shows sensitivity to Erythromycin but resistance to Penicillin.

How to Treat Erythrasma?

Erythrasma can be effectively treated with topical and oral antibiotics therapy, but the rate of occurrence is high. Topical ointments containing Fusidic acid, Clindamycin, or Erythromycin can be applied. Fusidic acid is used outside of the United States and acts by blocking aminoacyl-tRNA transfer to protein in bacteria. Fusidic acid ointment, according to studies, was found to be superiorly effective than oral Clarithromycin and Erythromycin. This superiority may be attributed to the acid’s ability to remove coproporphyrin III from the stratum corneum.

What Is the Prognosis of Erythrasma?

The outcomes are usually excellent, especially when a combination of oral and topical antibiotic therapies is used. Side effects and adverse effects like nausea, abdominal pain, hearing loss, metallic taste, ventricular arrhythmias, cholestatic jaundice, and toxic epidermal necrolysis may be expected from oral Clarithromycin and Erythromycin therapies. Additionally, favorable factors need to be eliminated; otherwise, recurrence may be expected. Erythrasma shows no residual sequelae in healthy individuals, but the infection may spread rapidly in predisposed immunocompromised individuals.

What Is the Differential Diagnosis of Erythrasma?

The differential diagnosis of erythrasma include:

• Seborrheic dermatitis.

• Inverse psoriasis.

• Candidiasis.

• Dermatophytosis.

• Tinea versicolor.

• Parapsoriasis.

• Pityriasis Rotunda.

What Are the Complications of Erythrasma?

The complications of erythrasma:

• Endocarditis.

• Abscess formation.

• Intravascular catheter infection.

• Cellulitis.

• Pyelonephritis.

Conclusion:

The skin changes may remain asymptomatic and first get observed by healthcare professionals during regular checkups, upon which they may be referred to dermatologists. Recurrence is a common association with this infection. The patients need to be educated on lifestyle modulations to reduce the recurrence risk. Additionally, they must be aware of the possible side effects and adverse effects of oral pharmacotherapy. Patients may use talcum over the body to prevent dampness, and humid environments must be managed with cooling solutions and clothing choices. Additionally, predisposing host factors must be eliminated along with dietary changes.