There are two forms of erythrasma: 1) interdigital and 2) generalized.

Interdigital erythrasma is more common than the generalized variant. It frequently appears on the 3rd and 4th web spaces of the foot, especially the 4th interdigital space [5]. The main characteristics of the lesions are maceration, scaling, and fissuring. These patients usually remain overall asymptomatic. Erythrasma may affect other areas such as the axillae, groin, and perineum. Furthermore, it targets moist regions such as infra breast, abdominal and intergluteal folds. Diabetics and obese women are particularly prone to infection in these areas.

At the onset of erythrasma, skin lesions are well demarcated pink-red scaly patches giving a wrinkled characteristic. They transform into brown-red macular patches and hence, this discoloration is observed in moist body folds. While the infection does not usually manifest in other symptoms, pruritus can occur. Erythrasma lasts from months to years. Some cases involve body-wide distribution such as the trunk and extremities.

Generalized erythrasma is more frequently observed in type 2 diabetics but can also occur in nondiabetics. Lesions extend beyond body folds. They are described as well-circumscribed erythematous patches that may be scaly or smooth. This type of infection is usually pruritic. Since these lesions may be confused with cutaneous dermatophytosis, potassium hydroxide preparation is used to differentiate these two.

Patients with recurrent episodes should be evaluated for diabetes. In fact, identifying and modifying this risk factor is important to prevent recurrence. Of importance, immunosuppressed individuals are susceptible to complications. Patients with erythrasma can also have concomitant infections with other organisms. These must be treated as well. Atypical cases are common and tend to appear with color variations. 

A careful exam of both feet and all body folds can differentiate erythrasma from other corynebacterial skin infections such as pitted keratolysis and trichomycosis axillaris. The clinical presentation of erythrasma is similar to that of tinea and intertrigo. An appropriate work up is key. 

• Intertrigo

  Intertrigo and secondary skin infections. Am Fam Physician. 2014; 89 (7): p.569-73. [amboss.com]

  Intertrigo has a spectrum of infectious and non-infectious causes (5). Skin fungal infections are among the major causes of intertrigo and affect a large scale of people worldwide (6). [ncbi.nlm.nih.gov]

  Risk Factors Similar to risks associated with Intertrigo III. Symptoms Usually asymptomatic May be pruritic in some cases IV. [fpnotebook.com]

  Compare intertrigo, tinea cruris. erythrasma infectious disease A patchy red-brown rash in the axilla and inguinal region, due to the presence of Corynebacterium minutissimum in the stratum corneum er·y·thras·ma ( er'i-thraz'mă ) An eruption of well-circumscribed [medical-dictionary.thefreedictionary.com]

• Eczema

  Essentials of Diseases of the Skin Including the Syphilodermata Arranged in the Form of Questions and Answers Prepared Especially for Students of Medicine (1822-64, eczema marginatum, erythrasma caused by fungus, and herpes zoster) and his successor, [wordnik.com]

  Cancer, Sunscreen Warnings, Acne, Aesthetic Mishaps, Eczema View Issue [practicaldermatology.com]

  […] usually causes no other symptoms apart from change of skin colour. ( sciencephoto.com ) If the patient has diabetes, obesity, or hyperhidrosis, erythrasma takes over complicated with secondary infection of the lesion, the occurrence of diaper rash and eczema [lookformedical.com]

  […] atopicum (dermatitis atopica) + Subacute and chronic (eczem) dermatitis + Microbial eczema + Granuloma gluteale infantum + Toxic contact (irritative) dermatitis, acute + Toxic contact (irritative) dermatitis, chronic + Seborrhoic dermatitis + Pityriasis [atlases.muni.cz]

  GENERALS - DIABETES MELLITUS - accompanied by – eczema ins. GENERALS - DIABETES MELLITUS abrom-a. acet-ac. adren. aether alf. all-s. allox. aloe alumn. am-act. anthraco. apoc. arg-met. arg-n. arist-m. Ars-br. ars. asc-c. aspar. aur-m-n. aur. bar-m. [homeopathyworldcommunity.ning.com]

• Skin Rash

  […] of the skin, rash, diaper rash, skin maceration and friction, lack of personal hygiene. ( diets-doctor.com ) The minute rash like appearance due to erythrasma begins as a slow growth encompassing a large patch of dry skin that is characterized by a fine-grained [lookformedical.com]

  (83.3%) 0.001 Scaling 1(10.0%) 35(97.2%) 3(10.7%) 5(83.3%) <0.001 Pigmentation 10(10.0%) 0 27(96.4%) 0 <0.001 Satellite lesions 1(10.0%) 0 0 3(50.0%) <0.001 Geographic skin rash 3(30.0%) 0 0 0 <0.001 Marginated skin lesions 0 9(25%) 0 0 0.006 Inflammation [ncbi.nlm.nih.gov]

• Vaginal Discharge

  discharge) Obesity Immunodeficiency Friction Lack of air circulation Secondary infection: Intertrigo is often colonized by fungal, viral, or bacterial pathogens, most commonly Candida albicans. [amboss.com]

The workup will include a detailed history and identification of predisposing factors as well as a thorough physical exam of both feet and all body folds. 

Microscopy and culture are both methods to diagnose erythrasma. Scrapings are used for evaluation. Under ultraviolet radiation from Wood light examination, erythrasma will fluoresce a coral red color. This is a characteristic finding of these lesions since corynebacteria produce excess porphyrins that accumulate under the skin [6]. Furthermore, hyphae are not found in skin scrapings unlike in tinea. It must be noted that if the patient has bathed prior to this examination, the characteristic finding may not be present [7].

Specific culture media can be utilized as well. Gram staining is also useful. Erythrasma lesions appear as gram positive filamentous rods. Methylene blue stain can reveal both the curved rods of C minutissimum and fungal spores of pityriasis versicolor in cases where both organisms exist [8]. Of important note, patients with recurrence should raise suspicion for underlying diabetes and a workup may be appropriate.  

• Streptococcus Pneumoniae

  […] pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae.4 Because higher drug concentrations are often achieved in macrophages, it is particularly effective against intracellular pathogens, such as Mycobacterium, Chlamydia, and Legionella.3 We [jamanetwork.com]

• Chlamydia

  […] pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae.4 Because higher drug concentrations are often achieved in macrophages, it is particularly effective against intracellular pathogens, such as Mycobacterium, Chlamydia, and Legionella.3 We [jamanetwork.com]

There are various treatment options available. Eliminating the infection, along with preventing complications and recurrence are the therapeutic goals for these patients.

Antibiotic treatment

One regimen consists of erythromycin (drug of choice) or tetracycline: 250mg taken orally 4 times daily for a duration of 14 days (these are effective for extensive infection). Oral erythromycin is very effective and has cure rates up to 100%. This is more efficient than tetracycline in patients with erythrasma affecting axillae, groin, and interdigital lesions. Chloramphenicol can also be used, but this is associated with potentially severe side effects. To assess the usability of clarithromycin further studies need to be conducted. While C minutissimum is susceptible to numerous antibiotics such as erythromycin, tetracycline, penicillins, cephalosporins, and others, multidrug resistance has emerged [9] [10] [11] [12]. 

Medication particularly effective for interdigital infection and prophylaxis

• Topical erythromycin or clindamycin 
• Fusidic acid cream
• Whitfield ointment
• Antibacterial soap 

Phototherapy

Photodynamic therapy using red light (broadband, peak at 635 nm) is another method to treat erythrasma. In one study investigating the effects of phototherapy on erythrasma in 13 patients, 23% experienced complete clearance, and the remaining patients showed improvement [13]. 

A thorough clinical evaluation is pertinent to identify all organisms as there could be coexisting infections. The clinician should establish treatment to target all of these. Antifungals are used in concomitant yeast infections. It is important to keep the lesions dry since these bacteria flourish in moist environments. The area should be washed with antibacterial soap and topical aluminum chloride. As always when developing a treatment regimen, the clinician should be aware of drug interactions and side effects especially in pregnant women, women on oral contraceptives, and patients with contraindications. Many antibiotics have drug interactions and side effects. 

Erythrasma is typically benign. While the prognosis is very good, there is a possibility for recurrence as long as there are risk factors present. In immunocompromised patients, it may become widespread and invasive, but this is rare. C minutissimum can cause other diseases in these high-risk cases. 

Corynebacterium minutissimum, which is present in the normal skin flora, is the organism responsible for erythrasma. This skin infection can affect anyone but is especially present in individuals with diabetes mellitus, obesity or other underlying diseases [1] [2]. Those residing in warm damp climates are also at higher risk due to production of body moisture. Additional risk factors for erythrasma include hyperhidrosis, poor hygiene, older age, and sensitive skin. Immunocompromised hosts are also susceptible.

The incidence of erythrasma is approximately 4%. While its occurrence is reported globally, it has a higher prevalence in tropical and subtropical regions [3]. One study emerging from Turkey reports that erythrasma was the cause of interdigital foot lesions in 46.7% of patients with this presentation [4]. 

As for patient demographics, this infection is more common in black and dark skinned individuals but can affect anyone. Furthermore, both genders are affected equally (except for crural lesions which are more common in men). However, one particular study reports interdigital erythrasma was more commonly observed in women than men [5]. Finally, erythrasma is found in all ages, but incidence increases with age. Reports indicate that it was even diagnosed in a 1-year-old child. 

When in warm and humid climates, C minutissimum proliferates in the stratum corneum (which is the outermost layer of the epidermis). Hence, this layer becomes thick. Furthermore, the bacteria enter the cells and intercellular spaces subsequently causing break down of the keratin fibrils. This organism is also responsible for porphyrin synthesis, which results in the red fluorescence of scales that appear under examination of Wood light.

Prevention can be achieved through numerous recommendations. First of all, modification of risk factors should be addressed through improvement of glycemic control as well as weight loss. Additionally, patients should maintain good hygiene, use antibiotic soap, wear clean clothing, avoid humid and hot weather if possible, and keep the skin and especially skin folds dry. Prevention of recurrence is also achieved through these measures. The clinician may prescribe prophylactic treatment as well. 

Erythrasma, caused by Corynebacterium minutissimum, is an intertriginous infection usually found in individuals with predisposing factors such as diabetes, obesity, and darker skin. It is most prevalent in tropical or subtropical regions due to humidity and dampness. The culprit of this infection is a component of the normal skin flora. Favorable risk factors allow for this organism to multiply under the skin.

The clinical presentation of erythrasma can be confused with infections such as tinea versicolor and cutaneous dermatophytosis, which are due to other organisms. Therefore, a detailed exam of the body folds and feet is necessary.

This is typically a benign condition. Most patients will have an interdigital infection of the feet but remain asymptomatic. However, diabetics, immunocompromised individuals, and others may also have systemic involvement as the disease is targeting groin, axilla, and other moist folds.

Ultraviolet light is utilized to diagnose erythrasma. It reveals a characteristic coral red emission due to the porphyria produced by this organism. Treatment aims to eradicate the infection and prevent complications and recurrences. Therapy consists of antibiotics and/or antifungals as well, depending on the presence of coexisting organisms. Recognizing and modifying risk factors such as implementing better glycemic control and weight loss are also important in the treatment and prevention of this infection.

Erythrasma is an infection of the skin due to the bacterium Corynebacterium minutissimum. It usually appears as scaling and cracking in the skin between the 4th and 5th toes. The infection can also occur in areas of the body where there are skin folds such as the armpits, the skin below the breasts, or the abdomen. In women, it can appear on the vaginal/anal skin and in men it can be seen on the scrotum.

Erythrasma is common in diabetic and obese patients. Also, there are other factors increasing the risk of infection, for example as excessive sweating in addition to living in hot and humid environments such as tropical regions. 

This mild infection does not usually produce symptoms. Also, there are other skin infections that look very similar. Your doctor will examine your feet and skin carefully. Examination of the infected skin or scrapings from the skin with ultraviolet light will confirm the diagnosis.       

Treatment includes antibiotics such as erythromycin or tetracycline. There are other medications that can be applied to the infected skin. Good results are achieved with the available drugs. Also, it is recommended that some patients use preventative treatment. If there is yeast found on the infected skin, then your doctor will prescribe antifungal treatment in addition. 

Treatment and prevention of future episodes is important. Preventative measures are as follows: wash the skin with antibacterial soap and dry the skin well, practice good hygiene, avoid hot, humid weather if possible, and keep your body dry. Since the risk of infection is higher in patients with diabetes and obesity, improving glucose control and weight loss are also advised. 

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