Erythrasma is a superficial skin infection that causes brown, scaly skin patches. It is caused by Corynebacterium minutissimum bacteria, a normal part of skin flora (the microorganisms that are normally present on the skin). There are two types of erythrasma: generalized and interdigital. Interdigital is the most common bacterial infection of the feet and normally does not show any symptoms. Not only is this an aesthetically unappealing condition, but there is evidence to support that disciform erythrasma can be an early sign of type 2 diabetes mellitus. The generalized erythrasma is most commonly seen in type 2 diabetes mellitus where the lesions go beyond the areas of the body where skin is rubbing together. It is prevalent among diabetics and the obese, and in warm climates; it is worsened by wearing occlusive clothing. The presence of erythrasma is approximately 4% and is more likely to be found in the subtropical and tropical areas compared to the rest of the world. It is found more commonly in African Americans due to the darker skin and  even though both sexes are affected, it is usually found more frequently in males for the thigh and leg regions. A great contributor to this infection is a weakened immune system which comes with aging, therefore the elderly are more susceptible to this disease than the young; this does not mean the young cannot be affected. The epidemiology background of erythrasma remains partially unsolved.
Erythrasma is often mistakenly diagnosed as dermatophytic infection which is a fungal infection and not a bacterial infection. The difference here is that fungi are multicellular and eukaryotes while bacteria are single celled prokaryotes. This is vital to differentiate because of the way they reproduce will indicate how the infection will spread throughout the human body. Mechanism
Corynebacterium minutissimum is the bacterium that causes this infection, often club shaped rods when observed under a microscope following a staining procedure, which is a result of snapping division which makes them look like a picket fence. This bacterium is gram positive, which means it has a very thick cell wall that cannot be easily penetrated. Electron microscopy confirms the bacterial nature of erythrasma, it shows decreased electron density in keratinized cells at the sites of proliferation. This means that the bacterium causes erythrasma by breaking down keratin Fibrils in the skin. Corynebacterium minutissimum consumes carbohydrates such as glucose, dextrose, sucrose, maltose, and mannitol.Erythrasma manifests mostly in slightly webbed spaces between toes (or other body region skin folds like the thighs/groin area) in warm atmospheric regions, and is more prevalent in dark skinned humans. As a person ages, they are more susceptible to this infection. This bacterium is not only found in warm atmospheric regions, but also warm and sweaty parts of the human body. Corynebacterium minutissimum survives the best here due to the encouraged fungal growth in these regions and allows it to replicate. It is more prevalent in African Americans due to their skin pigmentation.