The condition is common and occurs regularly among patients. However, it is even more common in warmer and tropical regions of the world.
Erythrasma is most common among adolescents and adults and occurs more frequently in men than women. Elderly patients, overweight individuals, diabetics, and patients with weakened immune systems are at greater risk for such skin infections.
In erythrasma, reddish-brown and well-defined skin changes are observed in the armpits, groin, and skin folds. Often, the skin changes start as faint reddish patches and then progress to a stronger rust-red colour. The characteristic colour is due to specific pigments (porphyrins) produced by the bacteria involved.
Sometimes the infection is localized to one area (e.g., one armpit), but typically it is symmetrically distributed (both armpits). The skin changes can also be present in multiple skin folds at the same time (e.g., armpits, under the breasts, and groin).
The skin changes generally cause few or no symptoms other than the visible skin alterations. A few individuals experience mild irritation and dry, scaly skin corresponding to the rash itself. Some may notice a slight odour or increased sweating. This is due to sulphur-like, foul-smelling substances produced by the bacteria.
The diagnosis of erythrasma is based on the appearance of the skin changes. In addition, a UV lamp (Woods lamp) can be used, which causes the skin changes to fluoresce with a strong coral-red colour in the dark. This fluorescence occurs because the bacteria's pigments absorb light from the UV lamp and then emit their own light waves.
In the vast majority of cases, swab cultures for bacterial growth and biopsies (tissue samples) are not necessary.
The skin infection is caused by a type of Corynebacterium bacteria (Corynebacterium minutissimum). This bacterium is normally present on the skin surface.
In erythrasma, the bacteria have favourable growth conditions over time (such as warm and moist skin), allowing them to multiply, produce abundant pigments, and eventually cause the characteristic skin changes.
The condition is treated with antiseptic wash or liquid antibiotics (liniment). In cases of extensive skin changes, oral antibiotic capsules may be necessary. In addition to the mentioned treatment, it is important to dry the affected skin areas well after showering. Erythrasma can usually be treated successfully, although many individuals may experience recurrences.
Erythrasma can closely resemble superficial fungal skin infections, which often occur in the groin area. Other skin conditions observed in skin folds, including intertrigo, psoriasis, and seborrheic dermatitis, can also resemble erythrasma.
