# A New In Vitro Model to Evaluate Anti-Adhesive Effect against Fungal Nail Infections
## 1 Introduction  
Fungi are present in the air, soil, plants and water. There are approximately 1.5-5.0 million different species of fungi on Earth, some of which cohabitate with humans, but only a few hundred of them may induce diseases. Fungal infections are ignored by social and political communities, but they affect more than a billion people; they cause approximately 11.5 million life-threatening infections and more than 1.5 million deaths annually [1]. Fungal infections can be mainly associated with two types of microorganisms: molds and yeasts. Dermatophyte infections are broadly present among fungal diseases all over the world [2]. They are filamentous fungi predisposed to infect keratin-rich tissues and contain three genera: _Trichophyton_ spp., _Microporum_ spp. and _Epidemophython_ spp. [3]. Dermatophytes can also be subdivided into three groups based on the source of infection: the anthrophilic group, where infection is transmitted from one human to another through the direct contact; the zoophilic group, where transfer occurs from animals to humans or other animals; and the geophilic group, consisting of dermatophytes transmitted to humans after contact with contaminated soil [2]. Dermatophytes in particular are hyaline-settled molds. The hyphae of these mycelial organisms penetrate the stratum corneum of the skin and nails. Fungal cells produce keratinocyte proteases that provide them with entry into the host [4]. Some dermatophyte species, which are basically soil saprophytes and which have acquired the ability to digest keratin debris in the soil, have evolved to be able to parasitize animal keratin tissues [5]. The term dermatapthytosis is used to describe infections by members of the genera _Microsporum_, _Trichophyton_ and _Epidernophyton_. At present, it has been recognized that dermatophyltosis includes the most common fungal infections worldwide, affecting 20-25% of the world population [3]. Until today, _Trichophyton rubrum_ has been the leading pathogen for skin and nail fungal infections. In fact, this dermatophytic fungus is the one most commonly encountered in temperate zones and in about 80% of cases [6], while _Microsporum canis_, _T. tonsurans_ and _T. violaceum_ are present as the predominant dermatophytes involved in tinea capitis [3]. Even if dermatophytes are the most common etiologic agents, yeasts and non-dermato phytee molds similarly constitute a substantial number of cases, depending on the geographical area [7,8]. In fact, in temperate countries, _Candida albicans_ infections have been shown to be recurrent since it can be isolated as frequently as dermatophytes [9]. Non-dermatophyte microorganisms can infect healthy skin and nails that have suffered some form of trauma, and they can aggravate existing dermatophyte infections. These include _Candida_, _Apergillus_ and _Alternaria_ species. _C. albicans_ infects fingernails, especially when people's hands are immersed in water regularly. Moreover, _C. albicans_ differs from other strains because it penetrates the nail plate only after the infection of the soft tissue around the nail has spread. The majority of these fungal infections are localized, but they could cause extensive necrosis of the involved tissue [10]. Non-dermatophytic molds cause 1.5-6% of cases of onychomycosis, mostly seen in the toenails of elderly individuals with a history of trauma (4 di cutils). Onychomycosis affects 5.5% of the world population and represents 20-40% of all onychopathies and approximately 30% of cutaneous mycotic infections [7]. Onychomycosis can be divided into three classes. The first class is represented by distal subungal onychomycosis (DSO), which is the most common form of onychomycosis. The fungus invades the nail bed and the lower part of the nail plate, starting from the hyponymcium.