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 ranges from 18 to 45%.Onychomycosis often occurs in the elderly, cancer patients and patients with diabetes, Kaposi's sarcoma and ichthyosis.
Onychomycosis is not only a cosmetic problem.It poses a serious threat to the human body, because the products (xanthomegnin, viomelein, substances similar to antibiotics 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-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 (damages the nails of the feet and hands, as well as 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.(it first affects the skin around the nails, and then penetrates the nail plate itself);
- molds (up to 1%) - Fusarium and Alternaria (most often found in immunodeficiency states).
Isolated onychomycosis is rare;simultaneous lesions of the skin of the feet, scalp and smooth skin are more often observed.
Infection occurs through household items: bathroom carpet, slippers, towel, manicure accessories;as well as when visiting the bathroom, sauna or swimming pool.Men are more susceptible to this pathology than women.Mostly adults suffer from onychomycosis;cases of mycosis of the nails are rare among children.
The risk group includes bathers, military personnel, athletes, people who regularly visit baths and saunas, miners.
The source of infection is the skin of the infected person's feet;sometimes entire families are affected.
Pathogenesis
Onychomycosis is a source of fungal infection that can cause sensitization of the organism.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 that occur when the toes are pinched with a tight shoe;humid and warm environment created by some low-quality shoes made of unnatural materials;the presence of serious diseases, immunodeficiency conditions, old 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 mold.In this type of lesion, the fungus in the nail bed enters from 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 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 caused by Trichophyton mentagrophytes, which causes the formation of white spots on the surface of the nail plate;as the process progresses, these points converge.This type of onychomycosis occurs in elderly patients with toe deformity, in which one toe covers the adjacent toe.The nail plate becomes dystrophic, crumbles, is colored grayish or brownish, but the matrix and epithelium of the bed are not affected, and there are no inflammatory phenomena on the skin.
- Proximal subungual onychomycosisthe rarest type in which the pathogen, usually red trichophyton, 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 separation of the nail plate is observed.With secondary bacterial contamination, the nail plate changes color.
- Total dystrophic onychomycosisit develops as a complication of distal lateral or, much less often, proximal subungual, and it also occurs in chronic subcutaneous candidiasis.With this form, the entire nail is affected by its complete destruction;the nail fold is either absent or pathologically thickened, while the normal nail plate cannot be formed.
All onychomycosis should be distinguished from psoriasis, eczema, lichen planus and other skin diseases.To confirm the diagnosis, it is necessary to perform microscopy of the pathological material from the lesion and culture of the pathogen on special identification media.
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 patient's general condition and his financial capabilities.
- Topical 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 in whom antimycotic tablets 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 they are not always able to penetrate to the nail bed, where the most persistent fungi are found.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 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 that 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 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 it is prescribed adequately.