They are generally caused by dermatophyte fungi or yeasts or molds able to penetrate the superficial layers of the skin and nails and colonize them permanently.
Their presence is not harmless: as they multiply and grow, these microorganisms progressively destroy the epidermis, the lamina, the bed or the nail matrix, altering its structure, functions and appearance, with aesthetic results that are anything but pleasant and, sometimes, causing damage such as to lead to the complete detachment of the nail.
Dermatophyte fungi
Dermatophyte fungi, so called because they are able to grow easily on human skin and its appendages (in particular, nails and hair), include a large group of microorganisms capable of infecting both animals and humans.
Of the twenty known species, only three are able to destroy keratin, the main protein present in the epidermis and nails, and to cause onychomycosis.
These are, in particular, Trichophyton rubrum, responsible for about 85% of dermatophytic nail infections, Trichophyton mentagrophytes, at the origin of about 12% of cases and Epidermophyton floccosum, highlighted in 2-3% of infected nails.
All these fungi are made up of elongated, ovoid cells, which are arranged in neat and branched rows like the crown of a tree, until they build intricate “mycelia” at the level of the nail and epidermis.
Each cell is externally protected by a rigid wall, which makes the fungus very resistant to external aggressions (including the action of soaps and detergents).
Below the wall, there is a plasma membrane, similar to the one surrounding human cells, which mediates the exchange of nutrients and metabolic waste between the inside and outside of the fungal cell, ensuring its survival.
Inside it, there are the cytoplasm (where all the vital reactions of the fungus take place) and the nucleus (containing the genetic material, essential to direct cellular functions and to allow the multiplication of the microorganism).
Candida albicans & co.
Among the yeasts, to cause nail infections are mainly those of the genus Candida and, in particular, the Candida albicans.
Contrary to dermatophyte fungi, it cannot be considered in all respects a pathogenic microorganism, since many people host it permanently on skin and mucous membranes without any problem, at least as long as the general immune defenses are efficient.
Episodes of colonization of mucous membranes (mouth, pharynx and vagina), skin (skin folds) and nails can occur, however, in situations of temporary immunosuppression, as often happens after antibiotic therapy or while taking corticosteroid drugs, and more often in the elderly.
Yeasts of the genus Candida consist of roundish cells that line up in branched rows, similar to dermatophyte fungi.
In general, they do not directly attack the nails, but the tissues that surround them, causing above all two clinical pictures: the “perionissis” (which affects the nails of the hands and is manifested by redness, swelling and disappearance of the cuticle at the base of the nail plate, generally, accompanied by pain and purulent secretions) and the “onychosis from Candida” (which gives the lamina a yellowish-gray color, sometimes associated with erosion and flaking of the nail).
How to counteract them
Dermatophyte fungi and yeasts love humid and warm environments, and are not afraid of the dark. For this reason they proliferate very easily on sweaty skin or not perfectly dried after normal washing, especially if covered by clothing or footwear.
For the same reason these microorganisms love skin folds, the spaces between the fingers and the small cracks that surround the nails, as well as the nails themselves. The first precaution to avoid seeing them proliferate is, therefore, to keep skin and fingers as dry as possible and exposed to air.
To specifically counteract the growth of fungi and yeasts that cause mycosis, drugs can be used to be applied locally (or, in severe cases, to be taken by mouth) containing substances capable of altering the functions and / or structure of their cells.
Among the most used compounds for this purpose are the “azolic” derivatives (imidazoles and triazoles), so defined for the characteristics of their molecule. All azoles share the ability to inhibit a specific enzyme present in fungi and yeasts, called “14α-methyl-lanosterol-demethylase”, essential for the synthesis of ergosterol (a phospholipid), the main component of the cell membranes of fungi and yeasts.
Without ergosterol, pathogenic microorganisms cannot survive and reproduce effectively, being gradually completely eliminated from skin and nails.
Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.
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