Fungal infection of toenails or onychomycosis is an infectious disease and is a fairly common pathology.The prevalence of toenail lesions in all countries of the world ranges from 18 to 45%.Onychomycosis often occurs in the elderly, cancer patients, and patients with diabetes mellitus, Kaposi's sarcoma, and ichthyosis.
Onychomycosis is not just an aesthetic problem.It poses a serious threat to the human body, since the products (xanthomegnin, viomellein, 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 liver disease, 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 toenails and fingernails, 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 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 (more often present 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: bath 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.Mostly adults suffer from onychomycosis;cases of nail mycosis are rare among children.
The risk group includes lifeguards, military personnel, athletes, people who regularly visit bathhouses and saunas, and miners.
The source of the 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 lesions of the skin of the feet and nails that occur when the toes are crushed by tight shoes;humid and hot environment created by some low-quality shoes made from non-natural materials;the presence of serious diseases, immunodeficiency states, old age.
Symptoms of the disease
Based on the differences in symptoms, four forms of onychomycosis are distinguished:
- Distal lateral (subungual) onychomycosis.the most common.The causative agents are red trichophyton, candida and, very rarely, molds.With this type of lesion the nail bed fungus enters the skin through the free edge of the nail and spreads towards the matrix.In this case, the nail plate, due to hyperkeratosis, gradually moves away from the bed and takes on 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 causes the formation of white spots on the surface of the nail plate;as the process progresses, these points merge.This type of onychomycosis occurs in elderly patients with toe deformities, in which one toe covers the adjacent one.The nail plate becomes dystrophic, crumbles and takes on a grayish or brownish color, but the matrix and epithelium of the bed are not affected and inflammatory skin phenomena do not occur either.
- Proximal subungual onychomycosisthe rarest type in which the pathogen, most often red trichophyton, penetrates the nail plate from the skin or periungual fold, then spreads along it and reaches the matrix and distal parts of the nail plate.As a result, a large detachment of the nail plate is observed.With secondary bacterial contamination, the nail plate changes color.
- Total dystrophic onychomycosisit develops as a complication of the distal lateral or, much less frequently, proximal subungual region and also occurs in chronic subcutaneous candidiasis.With this form the entire nail is affected with its complete destruction;the nail fold is absent or pathologically thickened, while a normal nail plate cannot form.
All onychomycosis should be differentiated 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 culture of the pathogen on special identification media.
Treatment of onychomycosis
When prescribing treatment to a patient suffering from onychomycosis, it is necessary to take into account a number of factors: 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 tablet types of antifungals are contraindicated.The most effective topical preparations include creams and paints.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 are not always able to penetrate to the nail bed, where the most persistent fungi are found.In these cases, the affected nail plate is removed surgically or with the help of special chemicals - keratolytics, and local treatment is continued.This method is inconvenient only due to the duration of the process, since it requires careful adherence to the treatment regimen for the entire time during which a healthy nail plate grows.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;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 can provide a pronounced therapeutic effect if prescribed properly.