Fungal nail infection (onychomycosis)
Causes
Onychomycosis is infection of the nails of the fi ngers or toes caused by dermatophytes (fungi that live on the outer keratinous layer of the skin), yeasts or moulds.
90% of toenail and 50% of fi ngernail infections are caused by the same Trichophyton and Epidermophyton species that cause athlete’s foot.
Predisposing factors include: increasing age, male gender, diabetes, nail trauma, excessive sweating, peripheral vascular disease, poor hygiene, athlete’s foot, immunodefi ciency and chronic exposure of the nails to water.
Epidemiology
Onychomycosis accounts for one-third of all fungal skin infections.
Prevalence in adults is estimated at between 3 and 8% and there are more than 1 million sufferers in the UK.
Infection rates in children are about 30 times lower than in adults, and in patients with diabetes about three times higher. Immunosuppressed and immunocompromised individuals also have a high susceptibility to infection.
The main form of fungal nail infection is distal and lateral subungual onychomycosis (DLSO). It is 20–30 times more common on toenails than fi ngernails.
Signs and symptoms
The nail is thickened and has turned yellow or white.
Changes usually start at the top of the nail but may spread across to the sides and down towards the nail base.
Debris created as a result of the infection accumulates under the nail.
There is scaling and distortion of the nail.
The nail may become brittle and some or all of it may break off.
Differential diagnosis
Psoriasis of the nails may appear similar to DLSO but it is also usually present at other skin sites. There is usually fi ne pitting on the nail surface, small salmon-coloured ‘oil drops’, and fi ngernails on both hands are affected.
(onychomycosis)
Lichen planus is an infl ammatory skin condition, the main features of which are itchy, fl at-topped papules, usually on the inner surfaces of the wrists and the lower legs. Nail involvement occurs in about 10% of patients (usually in more serious cases) and fi ne ridging or grooving can be seen, with severe dystrophy or even complete destruction of the nail bed.
Contact dermatitis occasionally resembles onychomycosis. Asking the patient about contact with possible irritants and fi nding the presence of contact dermatitis elsewhere on the body should differentiate the condition from DLSO.
Nail trauma: repeated damage to the nail can cause distal onycholysis (loosening of the nail, starting at the free edge and spreading to the root). This leads to colonisation by microorganisms and pigmentation of the area. If the onycholytic nail is clipped and the nail bed examined, it will appear normal with no subungual debris.
Yellow-nail syndrome is characterised by yellow nails and is commonly associated with lung disorders. The nails lack a cuticle, grow slowly and are loose or detached. All nails are affected.
Symptoms and circumstances for referral
Patients:
– with conditions that predispose to fungal infections (e.g. immunosuppression, diabetes, peripheral circulatory disorders)
– under 18 years of age
– with nail conditions other than clearly identifi ed DLSO
– with more than two infected nails
– with nail dystrophy or a destroyed nail
– showing no improvement after 3 months’ treatment.
Pregnant or breastfeeding women.
Treatment
Onychomycosis is one of the most diffi cult fungal infections to treat because of the time it takes for the nail to grow, the hardness of the nail plate and location of the infectious process (between the nail bed and plate).
Prescription treatments
Oral therapies. Terbinafi ne and itraconazole are considered the systemic treatments of choice.
Tioconazole 28% cutaneous solution is licensed for topical treatment of onychomycosis, but there is little clinical evidence of its effectiveness.
Non-prescription treatment: amorolfi ne 5% nail lacquer
Amorolfi ne 5% nail lacquer is licensed for pharmacy sale for the treatment of mild cases of DLSO, affecting up to two nails, in patients aged 18 years or over.
Amorolfi ne is a morpholine derivative, used topically as an antifungal, with a broad spectrum of activity against dermatophytes, other fungi and yeasts. Its fungicidal action is based on ergosterol depletion and the accumulation of ignosterol in fungal cytoplasmic membrane, which causes the fungal cell wall to thicken and chitin to be deposited.
The nail lacquer formulation builds a non-water-soluble fi lm on the nail plate that remains at the application site for a week, acting as a depot for the drug.
The product must be used weekly for up to 9 months, until all the infected nail has grown out and been replaced by healthy nail tissue.
A clinical trial demonstrated an overall cure in nearly 50% of patients after weekly treatment for 6 months, with overall improvement in a further 25%.
Adverse effects are rare and minor, amorolfi ne is not systematically absorbed and there are no known interactions with other drugs.
Additional advice
A cure cannot be achieved overnight. It is important that treatment is continued and directions are followed.
Wash and thoroughly dry feet every day.
To prevent the infection spreading to other toes, avoid tight-fi tting or occlusive shoes.
Rest shoes periodically to limit exposure to infectious fungi.
Use antifungal powders once a week to help keep shoes free from pathogens.
Exercise good nail care and be alert for infection recurrence.
Visit a podiatrist regularly.
Infection can be passed to others through contamination of shared facilities, so do not go barefoot in the family bathroom or public places.
Causes
Onychomycosis is infection of the nails of the fi ngers or toes caused by dermatophytes (fungi that live on the outer keratinous layer of the skin), yeasts or moulds.
90% of toenail and 50% of fi ngernail infections are caused by the same Trichophyton and Epidermophyton species that cause athlete’s foot.
Predisposing factors include: increasing age, male gender, diabetes, nail trauma, excessive sweating, peripheral vascular disease, poor hygiene, athlete’s foot, immunodefi ciency and chronic exposure of the nails to water.
Epidemiology
Onychomycosis accounts for one-third of all fungal skin infections.
Prevalence in adults is estimated at between 3 and 8% and there are more than 1 million sufferers in the UK.
Infection rates in children are about 30 times lower than in adults, and in patients with diabetes about three times higher. Immunosuppressed and immunocompromised individuals also have a high susceptibility to infection.
The main form of fungal nail infection is distal and lateral subungual onychomycosis (DLSO). It is 20–30 times more common on toenails than fi ngernails.
Signs and symptoms
The nail is thickened and has turned yellow or white.
Changes usually start at the top of the nail but may spread across to the sides and down towards the nail base.
Debris created as a result of the infection accumulates under the nail.
There is scaling and distortion of the nail.
The nail may become brittle and some or all of it may break off.
Differential diagnosis
Psoriasis of the nails may appear similar to DLSO but it is also usually present at other skin sites. There is usually fi ne pitting on the nail surface, small salmon-coloured ‘oil drops’, and fi ngernails on both hands are affected.
(onychomycosis)
Lichen planus is an infl ammatory skin condition, the main features of which are itchy, fl at-topped papules, usually on the inner surfaces of the wrists and the lower legs. Nail involvement occurs in about 10% of patients (usually in more serious cases) and fi ne ridging or grooving can be seen, with severe dystrophy or even complete destruction of the nail bed.
Contact dermatitis occasionally resembles onychomycosis. Asking the patient about contact with possible irritants and fi nding the presence of contact dermatitis elsewhere on the body should differentiate the condition from DLSO.
Nail trauma: repeated damage to the nail can cause distal onycholysis (loosening of the nail, starting at the free edge and spreading to the root). This leads to colonisation by microorganisms and pigmentation of the area. If the onycholytic nail is clipped and the nail bed examined, it will appear normal with no subungual debris.
Yellow-nail syndrome is characterised by yellow nails and is commonly associated with lung disorders. The nails lack a cuticle, grow slowly and are loose or detached. All nails are affected.
Symptoms and circumstances for referral
Patients:
– with conditions that predispose to fungal infections (e.g. immunosuppression, diabetes, peripheral circulatory disorders)
– under 18 years of age
– with nail conditions other than clearly identifi ed DLSO
– with more than two infected nails
– with nail dystrophy or a destroyed nail
– showing no improvement after 3 months’ treatment.
Pregnant or breastfeeding women.
Treatment
Onychomycosis is one of the most diffi cult fungal infections to treat because of the time it takes for the nail to grow, the hardness of the nail plate and location of the infectious process (between the nail bed and plate).
Prescription treatments
Oral therapies. Terbinafi ne and itraconazole are considered the systemic treatments of choice.
Tioconazole 28% cutaneous solution is licensed for topical treatment of onychomycosis, but there is little clinical evidence of its effectiveness.
Non-prescription treatment: amorolfi ne 5% nail lacquer
Amorolfi ne 5% nail lacquer is licensed for pharmacy sale for the treatment of mild cases of DLSO, affecting up to two nails, in patients aged 18 years or over.
Amorolfi ne is a morpholine derivative, used topically as an antifungal, with a broad spectrum of activity against dermatophytes, other fungi and yeasts. Its fungicidal action is based on ergosterol depletion and the accumulation of ignosterol in fungal cytoplasmic membrane, which causes the fungal cell wall to thicken and chitin to be deposited.
The nail lacquer formulation builds a non-water-soluble fi lm on the nail plate that remains at the application site for a week, acting as a depot for the drug.
The product must be used weekly for up to 9 months, until all the infected nail has grown out and been replaced by healthy nail tissue.
A clinical trial demonstrated an overall cure in nearly 50% of patients after weekly treatment for 6 months, with overall improvement in a further 25%.
Adverse effects are rare and minor, amorolfi ne is not systematically absorbed and there are no known interactions with other drugs.
Additional advice
A cure cannot be achieved overnight. It is important that treatment is continued and directions are followed.
Wash and thoroughly dry feet every day.
To prevent the infection spreading to other toes, avoid tight-fi tting or occlusive shoes.
Rest shoes periodically to limit exposure to infectious fungi.
Use antifungal powders once a week to help keep shoes free from pathogens.
Exercise good nail care and be alert for infection recurrence.
Visit a podiatrist regularly.
Infection can be passed to others through contamination of shared facilities, so do not go barefoot in the family bathroom or public places.
No comments:
Post a Comment