Intertrigo

Inflammation of opposed skin surfaces in body folds (axillae, groin, inframammary, inguinal creases, abdominal folds, interdigital spaces, neck folds in infants and natal cleft), caused by friction, heat, moisture and maceration.

• Secondary infection is frequent. The organisms are Candida albicans, dermatophytes, S. aureus, group A streptococci, Corynebacterium minutissimum (erythrasma), and Pseudomonas aeruginosa in moist or macerated folds.
• Risk factors: obesity, diabetes mellitus (including SGLT2 inhibitor use), hyperhidrosis, tight or occlusive clothing, immobility, incontinence, hot humid climates, poor hygiene, and in infants deep skin creases.
• It is a descriptive diagnosis that needs the cause identified, because treatment differs by cause.

• Symmetrical, well demarcated, erythematous, moist, macerated patches in the fold, with a glazed surface, a central fissure, and odour. Burning, itching and soreness are common.
• Candida produces a beefy red base with satellite papules and pustules beyond the edge. Erythrasma gives a dry, brown red, finely scaling patch (bright coral red under Wood lamp light). Dermatophyte infection gives a scaly, raised edge with central clearing. Bacterial infection gives yellow crusts, weeping and pustules.
• Differential diagnosis: inverse psoriasis, seborrhoeic dermatitis, contact dermatitis, hidradenitis suppurativa, Hailey-Hailey disease, Langerhans cell histiocytosis in infants, extramammary Paget disease (a chronic unilateral patch not responding to treatment), glucagonoma (necrolytic migratory erythema), zinc deficiency and tinea.
• Complications: secondary infection, cellulitis, fissuring and post-inflammatory hyperpigmentation.

• Clinical. Skin scrapings for potassium hydroxide preparation and fungal culture, bacterial swab, and Wood lamp (coral red fluorescence in erythrasma, green or blue green in Pseudomonas) are used when the cause is unclear or treatment fails.
• Check HbA1c or fasting glucose in all adults, and HIV status if recurrent or severe.
• Biopsy for non-responding or unilateral persistent disease to exclude Paget disease and other dermatoses.

• Fold care is the foundation:
  • Wash with a gentle soap free cleanser and dry thoroughly, including with a hairdryer on a cool setting.
  • Keep folds separated using absorbent cotton or moisture wicking fabric, and avoid tight clothing.
  • Apply zinc oxide paste or a barrier cream to inflamed non-infected skin, once or twice daily.
  • Control diabetes, lose weight, treat hyperhidrosis (aluminium chloride 20% hexahydrate solution at night to dry skin).
• Inflammation without clear infection: hydrocortisone 1% cream twice daily for no more than 7 days, combined with an antifungal if Candida is suspected (a combined preparation such as clotrimazole 1% with hydrocortisone 1% twice daily for 7 days).
• Candida: clotrimazole, miconazole 2% or ketoconazole 2% cream twice daily for 2 to 4 weeks. Nystatin 100,000 units/g cream 2 to 3 times daily is an alternative.
• Dermatophyte: terbinafine 1% cream once or twice daily for 1 to 2 weeks, or clotrimazole 1% twice daily for 2 to 4 weeks.
• Erythrasma: topical clindamycin 1% lotion or fusidic acid 2% cream twice daily for 2 weeks. Extensive or recurrent disease needs erythromycin 250 mg orally 6 hourly for 14 days (child 30 to 50 mg/kg per day in divided doses), or clarithromycin 1 g orally as a single dose.
• Bacterial (staphylococcal, streptococcal) infection: mupirocin 2% ointment three times daily for 5 to 7 days, and flucloxacillin 500 mg orally 6 hourly for 7 days (child 12.5 to 25 mg/kg 6 hourly) if extensive or with cellulitis.
• Pseudomonas: acetic acid 1% soaks twice daily, or topical gentamicin or silver sulfadiazine 1% cream. Oral ciprofloxacin 500 mg 12 hourly for 7 days if severe (adults only).
• Wet, weeping disease: potassium permanganate 1:10,000 soaks for 10 to 15 minutes twice daily for 2 to 3 days, or aluminium acetate 5% solution soaks, until dry.
• Special groups:
  • Infants: frequent diaper and fold care, zinc oxide barrier, miconazole 2% or nystatin for Candida, and avoid potent steroids.
  • Pregnancy: use barrier creams, topical clotrimazole or nystatin, and topical clindamycin. Avoid oral azoles and fluoroquinolones.
  • Diabetes: treat promptly, review SGLT2 inhibitor use if recurrent genital or fold Candida.
  • Immobile and elderly: nursing care to keep folds dry, with barrier creams.
• Follow up: review at 2 to 4 weeks. Refer to dermatology if there is no response, recurrent infection, or if hidradenitis, psoriasis or Paget disease is suspected.