Fungal infection of the toenails or onychomycosis is an infectious disease and is a fairly common pathology.The prevalence of toenail lesions in all countries of the world varies from 18 to 45%.Onychomycosis is common 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, viomelin, antibiotic-like substances and penicillin) of the vital activity of the fungus lead to long-term persistence in the affected nails and can lead to the development of hepatopathy, drug 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, as well as the skin), Trichophytonmentagrophytes (affects the nails of the first and fifth fingers and the skin of 3-4 interdigital folds), Epidermophytonfloccosum (nails of the first and fifth fingers);
- yeast (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;simultaneous lesions of the skin of the legs, scalp and smooth skin are more often observed.
Infection occurs through household items: bath rug, slippers, towel, manicure accessories;as well as when visiting a bath, sauna or swimming pool.Men are more susceptible to this pathology than women.Mostly adults suffer from onychomycosis;Among children, cases of mycosis of the nails are rare.
The risk group includes paramedics, military personnel, athletes, people who regularly visit baths and saunas, 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 are injuries to the skin of the feet and nails, which occur when the toes are pressed by tight shoes;moist and warm environment created by some low-quality shoes made of unnatural materials;the presence of serious diseases, conditions of immune deficiency, advanced age.
Symptoms of the disease
Based on the differences in symptoms, four forms of onychomycosis are distinguished:
- Distal lateral (subungual) onychomycosisthe most common.The causative agents are trichophyton red, candida and very rarely molds.In this type of lesion, the fungus in the nail bed enters from the skin through the free edge of the nail and spreads to the matrix.In this case, the nail plate, due to hyperkeratosis, gradually moves away from the bed and acquires a yellowish color.Thickening of the nail plate can occur and bacterial contamination gives the nail different colors ranging from greenish to dirty brown.
- White superficial onychomycosismost often it is caused by Trichophyton mentagrophytes, which causes the formation of white spots on the surface of the nail plate;as the process progresses, these spots merge.This type of onychomycosis occurs in elderly patients with a toe deformity in which one toe covers the adjacent toe.The nail plate becomes dystrophic, crumbles and turns grayish or brownish, but the matrix and epithelium of the bed are not affected and there are no inflammatory phenomena of the skin.
- Proximal subungual onychomycosisthe rarest type, in which the pathogen, most often trichophyton red, penetrates the nail plate from the skin or from the periungual fold, then spreads along it and reaches the matrix and distal parts of the nail plate.As a result, extensive detachment of the nail plate is observed.With secondary bacterial contamination, the nail plate changes color.
- Total dystrophic onychomycosisdevelops as a complication of the distal lateral or, much less often, the proximal subungual, and also occurs in chronic subcutaneous candidiasis.In this form, the entire nail is affected with its complete destruction;the nail fold is either absent or pathologically thickened, while a normal nail plate cannot form.
Any onychomycosis must be distinguished from psoriasis, eczema, lichen planus and other skin diseases.To confirm the diagnosis, it is necessary to perform microscopy of pathological material from the lesion and the culture of the pathogen on a special identification medium.
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 spread of the process, the general condition of the patient and his financial capabilities.
- Local means 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 in whom tablet types of antifungals 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 act effectively on the surface of the nail plate, but they 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 is continued.This method is inconvenient only because of the length of the process, as it requires careful adherence to the treatment regimen during the entire time that a healthy nail plate is growing.In this case, ointments should be applied daily, and varnishes - only once a week.
- Systemic therapy is more effective and reliable in the treatment of onychomycosis;used in case of failed local treatment.Indications for prescribing systemic drugs are the late stages of distal lateral and proximal subungual onychomycosis, as well as general onychomycosis.
The choice of drug for systemic treatment should be justified, taking into account the pharmacokinetics, spectrum of action and antifungal activity of each drug.It should not be forgotten that any drug can provide a pronounced therapeutic effect if it is prescribed adequately.