Updated: Sep 10, 2018
  • Author: Abdul-Ghani Kibbi, MD, FACP; Chief Editor: William D James, MD  more...
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Erythrasma is a chronic superficial infection of the intertriginous areas of the skin. The incriminated organism is Corynebacterium minutissimum, which usually is present as a normal human skin inhabitant. In 1996, Corynebacterium afermentans was reported in one case. [1]

In a more recent study, two colonies of Corynebacterium aurimucosum and Microbacterium oxydans were isolated from the interdigital web of the left foot in a 78-year-old woman indicating that other species of microorganisms may be responsible for this condition. [2]



Corynebacteria invade the upper third of the stratum corneum; under favorable conditions such as heat and humidity, these organisms proliferate. The stratum corneum is thickened. The organisms that cause erythrasma are seen in the intercellular spaces as well as within cells, dissolving keratin fibrils. The coral-red fluorescence of scales seen under Wood light is secondary to the production of porphyrin by these diphtheroids.



C minutissimum, a member of the normal skin flora, is the causative agent of erythrasma. The bacterium is a lipophilic, gram-positive, non–spore-forming, aerobic, and catalase-positive diphtheroid. C minutissimum ferments glucose, dextrose, sucrose, maltose, and mannitol.

Predisposing factors for erythrasma include the following:

  • Excessive sweating/hyperhidrosis

  • Delicate cutaneous barrier

  • Obesity

  • Diabetes mellitus

  • Warm climate

  • Poor hygiene

  • Advanced age

  • Other immunocompromised states




The incidence of erythrasma is reported to be around 4%. This infection is observed all over the world; the widespread form is found more frequently in the subtropical and tropical areas than in other parts of the world. [3]

In a study conducted in Turkey, the rate of erythrasma was found to be 46.7% among 122 patients with interdigital foot lesions. [4]


The incidence of erythrasma is higher in black patients.


Both sexes are equally affected by erythrasma; however, the crural form of erythrasma is more common in men. A 2008 study found that interdigital erythrasma was more common in women (83% of 24 patients). [5]


The incidence of erythrasma increases with age, but no age group is immune to the disease. The youngest patient reported to have erythrasma is a 1-year-old infant.



The prognosis for erythrasma is excellent; however, the condition tends to recur if the predisposing factors are not eliminated.

Erythrasma is usually a benign condition. However, it may become widespread and invasive in predisposed and immunocompromised individuals; this is very rare in immunocompetent hosts. In such individuals, this organism has caused infections other than erythrasma. These include abscess formation (3 cases), [6] intravascular catheter–related infections (2 cases), [7] primary bacteremia (3 cases), peritoneal catheter–related infections (2 cases), [7, 8] endocarditis (2 cases), [9, 10] pyelonephritis (2 cases), [11, 12] cellulitis (1 case), [13] endophthalmitis (1 case), [14] arteriovenous fistula infection (1 case), cutaneous granuloma (1 case), [15] and meningitis (1 case). [16]

The first case of postoperative intraabdominal infection caused by Corynebacterium minutissimum in an immunocompetent adult host was reported and has been successfully treated with intravenous amoxicillin/sulbactam. [17]


Patient Education

Patients with erythrasma should be instructed to keep the area dry.