Onychomycosis
Onychomycosis means fungal infection of the nails. It represents up to 20% of all nail disorders.
Onychomycosis may affect toe- or fingernails, but toenail infections are particularly common.
- The most common type of onychomycosis (80-90%), caused by dermatophytes, is known as tinea unguium (tinea of the nails).
It can result in
- discoloration,
- thickening,
- chalkiness,
- crumbling of the nails and is often treated by powerful oral medications
Classification of Onychomycosis
Onychomycosis is classified according to the clinical pattern of nail bed involvement. The main types are:
- Distal and lateral subungual onychomycosis (DLSO); The most common form of tinea unguium usually caused by Trichophyton rubrum, which invades the nail bed and the underside of the nail plate.
- Superficial white onychomycosis; Caused by fungal invasion of the superficial layers of the nail plate to form “white islands” on the plate. Accounts for only 10 percent of onychomycosis cases.
- Proximal subungual onychomycosis; Fungal penetration of the newly formed nail plate through the proximal nail fold. It is the least common form of tinea unguium in healthy people but found more commonly when the patient is immunocompromised.
- Endonyx onychomycosis; Fungal penetration through the full thickness of the nail from directly under the skin. The nail bed is not infected. Commonly found in immunocompromised conditions.
- Total dystrophic onychomycosis; Total destruction of the nail plate. It is the end result of any of the above four types.
Causes of Onychomycosis
- Dermatophytes are the fungi mostly responsible for onychomycosis
- Trichophyton rubrum is the most common dermatophyte fungi.
- Others include, Trichophyton interdigitale and Epidermophyton floccosum, can be causes as well.
- The dermatophytes are identified in 90% of the toenail and 50% of fingernail onychomycosis.
- Candida albicans accounts for 2% of onychomycosis, occurring especially in fingernails.
- Yeasts mainly cause fingernail onychomycosis in people whose hands are often submerged in water.
Risk Factors
- Age; The most common risk factor for onychomycosis is aging. Reason may be due to nail trauma, poor nail care, poor peripheral circulation e.t.c.
- Family history of onychomycosis
- Warm and moist conditions of the fingers like wearing tight fitting shoes
- Walking with barefoot in public places such as swimming pool, public baths and showers.
- Nail conditions such as tinea pedis, nail injury, nail damage, psoriasis .
- Conditions that are related with poor peripheral circulation such as diabetes or peripheral arterial disease.
- Immunodeficient conditions like cancer , post transplant care , HIV , patients on chemotherapy and radiotherapy
Clinical Presentation.
- Always presents with distorted nails .
- Change in nail texture and discoloration.
- The nail plate can have a thickened, yellow, or cloudy appearance.
- The nails can become rough and crumbly, or can separate from the nail bed.
- Malodor; slight foul smelling of the infected nail.
Complications.
- Cellulitis
- Sepsis
- Osteomyelitis
- Tissue damage
- Loss of nail
Management / Treatment of Onychomycosis
Oral medications such as Oral antifungal medications such terbinafine , itraconazole and fluconazole , Treatment Options
Preferred treatment regimen:
Terbinafine 250 mg orally OD (children <20 kg: 67.5 mg/day, 20–40 kg: 125 mg/day, >40 kg: 250 mg/day) for 6 weeks OR Itraconazole 200 mg orally O.D for 3 months OR Fluconazole 150–300 mg orally weekly for 6–12 months
Fungal laser therapy; Laser treatments aim at either stopping fungal reproduction (fungistatic) or killing fungus (fungicidal).
Prevention of Onychomycosis
- Wear appropriate fitting shoes. Both, shoes that are too tight and or too loose can cause trauma to the toenails, creating a portal of entry for fungal organisms.
- Avoid being barefoot in public or communal areas that are shared by other barefoot people. These areas may include public swimming pools, locker rooms, showers, and hotel rooms.
- Do not pick or tear at your toenails. Use clean instruments to cut the toenails straight across, avoiding rounding the edges. Trauma or aggressive cutting can create portals of entry for fungus.
- Thoroughly dry your feet, including between your toes after showering.
- Maintain dry feet throughout the day and do not wear damp shoes.
- If you have family members with foot or toenail fungal infections, avoid sharing common spaces barefoot.
- If you have diabetes or reduced blood flow to the feet, maintain foot exercises and guidelines from the healthworker.
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