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InfectionCommon DDxICD-10 L08.1

Erythrasma

Corynebacterium minutissimum infection

Erythrasma is a chronic superficial bacterial infection of the intertriginous areas caused by Corynebacterium minutissimum. It produces well-demarcated red-brown patches with fine scale in flexural skin. Coral-red fluorescence under Wood's lamp is pathognomonic, due to bacterial porphyrin production. UK clinical relevance is principally as a DDx for tinea, candidiasis, inverse psoriasis, seborrhoeic dermatitis and extramammary Paget disease.

CurrentLast reviewed 16 May 2026
Clinical image of Erythrasma
Erythrasma. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Microbiology

  • Corynebacterium minutissimum: gram-positive aerobic rod; commensal of skin (intertriginous sites).
  • Overgrowth in warm, moist intertriginous environment.
  • Produces porphyrins → coral-red Wood lamp fluorescence.
  • Risk factors: obesity, diabetes, hyperhidrosis, occlusion, immunosuppression, poor hygiene, hot humid climate.

Clinical features

  • Well-demarcated red-brown patches with fine scale and slight wrinkling.
  • Sites:
    • Toe webs (commonest in temperate climates).
    • Groin (vs tinea cruris).
    • Axillae.
    • Inframammary.
    • Intergluteal cleft.
    • Genitocrural.
  • Mild itching or asymptomatic.
  • Chronic, indolent.
  • Generalised erythrasma in immunocompromised / chronic disease.

Differentials

  • Tinea cruris — advancing scaling edge; KOH+; no coral-red fluorescence.
  • Cutaneous candidiasis — beefy red; satellite pustules.
  • Inverse psoriasis — sharply demarcated; bright red; lacks scale; family / personal history of psoriasis.
  • Seborrhoeic dermatitis — greasy scale; nasolabial / scalp also affected.
  • Hailey-Hailey disease — flexural maceration; family history.
  • Extramammary Paget disease — chronic, refractory, biopsy if persistent.
  • Acanthosis nigricans (intertriginous).
  • Pitted keratolysis on plantar / toe-webs — pits + odour.

Investigations

  • Wood lamp: coral-red fluorescence (porphyrins) — pathognomonic when present; may be absent if recent washing.
  • KOH: negative for fungal hyphae (excludes tinea / candidiasis).
  • Gram stain: filamentous Gram-positive rods.
  • Culture rarely needed.
  • Bloods: HbA1c, BMI assessment, immune status if generalised.

Management

  • Topical:
    • Clindamycin 1% solution BD for 2-4 weeks.
    • Erythromycin 2% solution.
    • Fusidic acid 2% cream.
    • Topical imidazoles (clotrimazole, miconazole) effective due to overlapping spectrum.
    • Whitfield ointment (salicylic + benzoic acid) for adjunct keratolysis.
  • Oral for extensive / refractory disease:
    • Erythromycin 250-500 mg QDS for 7-14 days.
    • Clarithromycin 500 mg BD.
    • Doxycycline 100 mg OD.
  • General:
    • Treat hyperhidrosis (aluminium chloride).
    • Loose breathable clothing.
    • Weight management; glycaemic control.
    • Antibacterial soap or chlorhexidine wash to flexures.
  • Counsel:
    • Recurrence common with predisposing factors.
    • Persistent disease warrants re-examination and biopsy to exclude EMPD.

References

  1. Holdiness MR. Management of cutaneous erythrasma. Drugs. 2002;62:1131-1141.
  2. Morales-Trujillo ML et al. Interdigital erythrasma: clinical, epidemiologic, and microbiologic findings. Actas Dermosifiliogr. 2008;99:469-473.
  3. British Association of Dermatologists. Erythrasma — patient information leaflet. London: BAD; 2023.
  4. Sariguzel FM et al. Antimicrobial susceptibilities of Corynebacterium minutissimum isolated from erythrasma. J Eur Acad Dermatol Venereol. 2014;28:1377-1380.

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