Fungal infection of toenails or onychomycosis is an infectious disease and a very common pathology.The prevalence of toenail injuries 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 a cosmetic problem.It poses a serious threat to the human body, since the products (xanthomegnin, viomelain, 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-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 toenails and fingernails, as well as 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 it affects the skin around the nails, and then penetrates the nail plate itself);
- molds (up to 1%) - Fusarium and Alternaria (more often found in immunodeficiency states).
Isolated onychomycosis is rare;more often, simultaneous lesions on the skin of the feet, scalp and smooth skin are observed.
Infection occurs through household items: bathroom rug, slippers, towel, manicure accessories;as well as when visiting a bathhouse, sauna or swimming pool.Men are more susceptible to this pathology than women.Mainly adults suffer from onychomycosis;among children, cases of nail mycosis are rare.
The risk group includes bathhouse attendants, military personnel, athletes, regular visitors to bathhouses and saunas and miners.
The source of infection is the skin on 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.Furthermore, mushrooms release substances that are toxic to the human body.
Predisposing factors for infection are lesions on the skin of the feet and nails that occur when the toes are squeezed by tight shoes;humid and hot environment created by some low-quality shoes made from unnatural materials;the presence of serious illnesses, immunodeficiency states, old age.
Symptoms of the disease
Based on 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 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 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 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 deformity, in which one toe covers the adjacent one.The nail plate becomes dystrophic, collapses and has a grayish or brownish color, but the matrix and bed epithelium are not affected and there are no inflammatory phenomena in the skin.
- 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, extensive 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 subungual or, much less frequently, the proximal subungual, and also occurs in chronic subcutaneous candidiasis.With this form, the entire nail is affected with its total destruction;the nail fold is absent or pathologically thickened, while a normal nail plate cannot form.
All onychomycosis must be differentiated 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 the pathogen in special identification media.
Treatment of onychomycosis
When prescribing treatment to a patient with onychomycosis, several 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 tablet types of antimycotics 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 are not always able to penetrate the nail bed, where the most persistent fungi are located.In such 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 because of the duration of the process, as it requires careful adherence to the treatment regimen throughout the entire period of growth of a healthy nail plate.In this case, ointments should be applied daily and varnishes only once a week.
- Systemic therapy is more effective and reliable in treating onychomycosis;is used when local treatment fails.Indications for prescribing systemic medications are the late stages of lateral and proximal distal subungual onychomycosis, as well as total onychomycosis.
The choice of medication for systemic treatment must be justified, taking into account the pharmacokinetics, spectrum of action and antifungal activity of each medication.It should not be forgotten that any medication can provide a pronounced therapeutic effect if prescribed correctly.