Erythrasma overview

# Overview
Erythrasma is a dermatological disease caused by Corynebacterium minutissimum. Erythrasma was first officially identified by Burchardt in 1859. Corynebacterium minitissium was first isolated and discovered to be the cause of Erythrasma in 1961. Erythrasma usually presents with erythematous lesions, maceration, and reddish-brown scales indicative of hyperkeratosis. The lesions are usually found in skin folds, and also commonly present in the interdigital regions in hands and feet. Symptoms include reddish-brown scaly patches, itching, pain if irritated, skin shedding, blisters, softening and whitening of the skin, foul odor, and thickening and yellowing of the toenails. Erythrasma develops when Corynebacterium minitissium infiltrates the stratum corneum and proliferate. Hyperkeratosis leads to the formation of reddish-brown lesions characteristic of erythrasma. Microscopic pathology of erythrasmas includes thickening of stratum corneum, decreased electron density around intracellular bacteria and those in direct contact with the cell wall, and widening of intracelluar space, allowing bacterial invasion, and separation of the horny cells. Erythrasma is most commonly found in women over 40 years old, in individuals living in humid and tropical/subtropical climates, and in military personnel. Risk factors for erythrasma include individual and environmental conditions predisposing bacterial infection and proliferation. This includes overweight and obesity, diabetes, immunocompromise, and hyperhidrosis. Erythrasma must be differentiated from other dermatological conditions that present with reddish-brown scales and itching, as well as other diseases resulting from corynebacteria infection. Diagnostic laboratory tests performed for suspected Erythrasma include those that confirm a Corynebacterium minitissimum infection. The most common laboratory test is a Wood's lamp examination; coral-red fluorescence is indicative of Corynebacterium minitissimum. The mainstay of erythrasma medical therapy is topical and systemic antibiotic therapy. The primary antibiotics used for local and widespread infection include fusidic acid, clindamycin, clarithromycin, and erythromycin, respectively. Additionally, there are studies that display efficacy of systemic administration of tetracycline and chloramphenicol. There is evidence that fusidic acid therapy is more effective than topical clarithromycin and systemic erythromycin, but may be indicated less due to poorer efficiency and patient compliance. Administration of chloramphenicol is limited due to its suppression of bone marrow and heightening risk of developing neutropenia, agranulocytosis and aplastic anaemia. Effective measures of preventing erythrasma are preventative of Corynebacterium minutissimum infection and proliferation. Secondary prevention of erythrasma involves prophylactic use of antibacterial soap on the previously affected region.

# Historical Perspective
Erythrasma was first officially identified by Burchardt in 1859. Corynebacterium minitissium was first isolated and discovered to be the cause of Erythrasma in 1961.

# Classification
There is no classification system established for erythrasma.

# Pathophysiology
Erythrasma develops when Corynebacterium minitissium infiltrates the stratum corneum and proliferates. Hyperkeratosis leads to the formation of reddish-brown lesions characteristic of erythrasma. Microscopic pathology of erythrasma includes thickening of stratum corneum, decreased electron density around intracellular bacteria and those in direct contact with the cell wall, and widening of intracelluar space, allowing bacterial invasion, and separation of the horny cells. Erythrasma is associated with dermatological conditions, including additional corynebacterium pathologies.

# Causes
Erythrasma is caused by Corynebacterium minutissimum.

# Differentiating Erythrasma from Other Diseases
Erythrasma must be differentiated from other dermatological conditions that present with reddish-brown scales and itching, as well as other diseases resulting from corynebacteria infection.

# Epidemiology and Demographics
Global epidemiological and demographical information for erythrasma is not well documented. Among diagnosis of dermatomycoses, the incidence of erythrasma was approximated as 4,500 per 100,000 individuals in 1951. Studies on erythrasma prevalence have found high rates in military populations. Erythrasma is most common in individuals over 40 years old. Women are more commonly affected by erythrasma than men. There is no known racial predisposition to erythrasma. Erythrasma of the groin is more commonly found in humid, tropical or subtropical regions; interdigital erythrasma does not have a geographic predisposition.

# Risk Factors
Risk factors for erythrasma include individual and environmental conditions predisposing bacterial infection and proliferation.

# Screening
There is no diagnostic screening procedure for erythrasma.

# Natural History, Complications, and Prognosis
Upon Corynebacterium minitissium infection, the affected region of the epidermis becomes erythematous and present with pruritus. As hyperkeratosis and keratolysis occurs, the red-pink lesions becomes reddish-brown and begins to scale and shed. Without treatment, the lesions usually remain and spreading occurs concurrent with the spread of bacterial infection. Complications of erythrasma result from persistence of symptoms or spread of infection. Without treatment, the prognosis for erythrasma varies based on the emergence and presence of complications. With treatment, the prognosis for erythrasma is good; complete resolution of symptoms and recovery is expected.

# Diagnosis

## History and Symptoms
Erythrasma usually presents with reddish-brown scaly patches, itching pain if irritated, skin shedding, blisters, softening and whitening of the skin, foul odor, and thickening and yellowing of the toenails. Erythrasma patients should be examined for history of overweight or obesity, diabetes, and hyperhidrosis.

## Physical Examination
Erythrasma presents with erythematous lesions, maceration, and reddish-brown scales indicative of hyperkeratosis. The lesions are usually found in skin folds, and also commonly present in the interdigital regions in hands and feet. Erythrasma patients are usually well-appearing, barring complications.

## Laboratory Findings
Laboratory tests performed for suspected erythrasma include those that confirm a Corynebacterium minitissimum infection. The most common laboratory test is a Wood's lamp examination; coral-red fluorescence is indicative of Corynebacterium minitissimum. A culture may be performed to specify the pathogen; Corynebacterium minutissimum will present as non-hemolytic smooth colonies that are 1-1.5mm in size. Gram stain analysis of Corynebacterium minitissimum may reveal slightly curved bacterial rods that display violet or blue coloration, indicative of gram positive.

## Imaging Findings

### Electrocardiogram
There are no diagnostic electrocardiogram findings for erythrasma.

### X Ray
There are no diagnostic x ray findings for erythrasma.

### CT
There are no diagnostic CT findings for erythrasma.

### MRI
There are no diagnostic MRI findings for erythrasma.

### Echocardiography or Ultrasound
There are no diagnostic echocardiography or ultrasound findings for erythrasma.

### Other Imaging Findings
A Wood Lamp examination is commonly performed on patients with suspected Erythrasma to determine a Corynebacterium minitissimum infection. Coral-red fluorescence is indicative of Corynebacterium minitissimum, as a result of produced coproporphyrin III.

# Treatment

## Medical Therapy
The mainstay of erythrasma medical therapy is topical and systemic antibiotic therapy. The primary antibiotics used for local and widespread infection include fusidic acid, clindamycin, clarithromycin, and erythromycin, respectively. Additionally, there are studies that display efficacy of systemic administration of tetracycline and chloramphenicol. There is evidence that fusidic acid therapy is more effective than topical clarithromycin and systemic erythromycin, but may be indicated less due to poorer efficiency and patient compliance. Administration of chloramphenicol is limited due to its suppression of bone marrow and heightening risk of developing neutropenia, agranulocytosis and aplastic anaemia.

## Surgery
Surgical intervention is not recommended for the management of erythrasma.

## Primary Prevention
Effective measures of preventing erythrasma are prevention of Corynebacterium minutissimum infection and proliferation.

## Secondary Prevention
Secondary prevention of erythrasma involves prophylactic use of antibacterial soap on the previously affected region.