Fungal infection of toenails, or onychomycosis, is an infectious disease and a fairly common pathology.The prevalence of toenail lesions ranges from 18 to 45% in all countries of the world.Onychomycosis often occurs in the elderly, cancer patients and patients with diabetes mellitus, Kaposi's sarcoma and ichthyosis.
Onychomycosis is not just a cosmetic problem.It poses a serious threat to the human body, since the products (xanthomegnin, viomellein, antibiotic-like substances and penicillin) of the fungus's vital activity lead to long-term persistence in the affected nails and can lead to the development of hepatopathy, drug-induced toxicoderma and even Lyell's syndrome.
Etiology and epidemiology
The causative agents of onychomycosis are represented by three groups of fungi:
- Dermatophytes (up to 95%) – Trichophyton rubrum (causes damage to the nails of the feet and hands and the skin), Trichophytonmentagrophytes (affects the nails of the first and fifth toes and the skin of 3-4 interdigital folds), Epidermophytonfloccosum (nails of the first and fifth toes);
- Yeast fungi (up to 4%) – Candida spp.(first affects the skin around the nails and then penetrates the nail plate itself);
- Molds (up to 1%) – Fusarium and Alternaria (most common in immunodeficiency states).
Isolated onychomycosis is rare;more often, simultaneous lesions of the skin of the feet, scalp and smooth skin are observed.
Infection occurs through household items: bathroom carpet, slippers, towel, manicure accessories;as well as when visiting a bathhouse, sauna or swimming pool.Men are more susceptible to this pathology than women.Adults in particular suffer from onychomycosis;Cases of nail mycosis are rare in children.
The risk group includes bathhouse attendants, military personnel, athletes, people who regularly visit bathhouses and saunas, and miners.
The source of infection is the skin of the feet of an infected person;sometimes entire families are affected.
Pathogenesis
Onychomycosis is a source of fungal infection that can cause sensitization of the body.In addition, mushrooms release substances that are toxic to the human body.
Predisposing factors for infection include injuries to the skin of the feet and nails that occur when the toes are pinched by tight shoes;humid and warm environment caused by low-quality shoes made from non-natural materials;the presence of serious diseases, immunodeficiency states, age.
Symptoms of the disease
Based on different symptoms, four forms of onychomycosis are distinguished:
- Distal lateral (subungual) onychomycosismost frequently.The pathogens are Trichophyton red, Candida and, very rarely, mold.In this type of lesion, the fungus in the nail bed invades from the skin through the free edge of the nail and spreads towards the matrix.In this case, due to hyperkeratosis, the nail plate gradually moves away from the nail bed and acquires a yellowish color.Thickening of the nail plate may occur and bacterial contamination gives the nail a variety of colors ranging from greenish to dirty brown.
- White superficial onychomycosismost often caused by Trichophyton mentagrophytes, which leads to the formation of white spots on the surface of the nail plate;As the process progresses, these spots merge.This form of onychomycosis occurs in older patients with a toe deformity in which one toe covers the adjacent toe.The nail plate becomes dystrophic, crumbles and turns grayish or brownish in color, but the matrix and epithelium of the nail bed are not affected and no inflammatory phenomena of the skin appear.
- Proximal subungual onychomycosisThe rarest form, in which the pathogen, most commonly red trichophyton, penetrates the nail plate from the skin or periungual fold, spreads along it and reaches the matrix and distal parts of the nail plate.This results in large-scale detachment of the nail plate.With secondary bacterial contamination, the nail plate becomes discolored.
- Total dystrophic onychomycosisdevelops as a complication of distal-lateral or, much less commonly, proximal-subungual candidiasis and also occurs in chronic subcutaneous candidiasis.In this form, the entire nail is affected and is completely destroyed;The nail fold is missing or pathologically thickened, while a normal nail plate cannot form.
Any onychomycosis should be differentiated from psoriasis, eczema, lichen planus and other skin diseases.To confirm the diagnosis, microscopy of the pathological material from the lesion and culture of the pathogen on special identification media is required.
Treatment of onychomycosis
When prescribing treatment for a patient with onychomycosis, a number of factors must be taken into account: the type of pathogen, the prevalence of the process, the general condition of the patient and his financial capabilities.
- Local agents are often used in the treatment of distal and lateral subungual onychomycosis when no more than 3 nails are affected, as well as in patients for whom antifungal drugs in tablet form are contraindicated.The most effective topical preparations include creams and varnishes.They are often combined to achieve a faster therapeutic effect.The preparations contain high concentrations of active ingredients;They work effectively on the surface of the nail plate, but cannot always penetrate to the nail bed, where the most stubborn fungi are located.In such cases, the affected nail plate is removed either surgically or with the help of special chemicals - keratolytics - and local treatment continues.This method is inconvenient only due to the length of the process, as it requires careful adherence to the treatment plan throughout the entire period of growing a healthy nail plate.In this case, ointments should be applied daily and varnishes only once a week.
- In the treatment of onychomycosis, systemic therapy is more effective and reliable;It is used when local treatment fails.Indications for prescribing systemic drugs are the late stages of distal-lateral and proximal subungual onychomycosis, as well as total onychomycosis.
The choice of drug for systemic treatment must be justified taking into account the pharmacokinetics, spectrum of action and antifungal activity of each drug.It should not be forgotten that any drug, when prescribed appropriately, can have a pronounced therapeutic effect.