Fungus – Erythrasma

Erythrasma is a rather uncommon infection, which I may frequently in my the Woodlands dermatology and Conroe dermatology clinics.  It is a bacterial infection that arises from a normal skin flora inhabitant,Cornybacterium minutissimum, which overgrows in areas of warmth, heat and moisture such as the intertriginous folds under the arms and in the groin.  The bacteria grows in the stratum corneum and usually remains very superficial.  Only in rare cases, would Cornybacterium minutissimum become invasive and result in an abscess or a fatal septicemia.  Clinically. eryhrasma results in a rash that forms a circular brown/red plaque that may mimic a fungal rash.  On diagnostic workup, the KOH is negative under microscopy but a Wood’s lamp can be illuminated on the rash revealing a coral red fluorescence.  This is a diagnostic finding as the bacteria produces a porphyrin, which is a chemical that fluoresces under certain lights.  Sometimes this fluorescence is not visible if a patient has bathed just prior to coming into clinic, as soap and water can wash away the porphyrin.  Erythrasma is easily treated with either a topical or oral antibiotic such as clindamycin or erythromycin.  In patients who have recurrent bouts of erythrasma, an underlying condition such as diabetes may be suspected.