Update on Fungal Disease: From Establish Infection to Clinical Manifestation

Abstract

Fungal diseases have emerged as an important cause of morbidity and mortality, especially among immunocompromised patients. Pathogenic fungi have evolved an array of virulence factors to survive within the host and to outwit immune defenses. Fungi may cause a wide range of diseases in humans that range in extent from superficial to disseminated infections. Generally, the site of infections classifies the type of fungal disease, which can be divided into superficial, cutaneous, subcutaneous and systemic. In addition, the fungal virulence factors determine whether the infection will become established in the host. A primary pathogen may infect an immunologically normal host, whereas, an opportunistic pathogen requires some compromise of the host immune defenses in order for the infection to become established. This article covers the main fungi that are responsible for the increase of the fungal infections.Keywords: Fungal infections; Virulence; Yeast; Opportunistic infections; Endemic mycosis Fungal InfectionsFungal diseases have changed constantly in the last years. The virulence of these microorganisms has been adapted according to the human host, promoting a range of clinical manifestation. Several are the ways by which fungi promote a disease depending on human body part involved by the microorganism and the immunologic system of the host [1].In this review, we discuss the main fungal pathogens responsible for causing several diseases, highlighting on their virulence associate to clinical manifestation and the difficulty to accomplish the treatment. Superficial and cutaneous fungal diseasesSuperficial and cutaneous fungal infections are very common and occur worldwide affecting millions of people, especially immunocompromised patients. The most common types of these infections are dermatophytosis (tinea or ringworm), pityriasis versicolor (formerly tinea versicolor) and candidiasis (moniliasis). These occur by fungal invasion into the skin, keratinized tissues and mucous membranes [2]. Trichosporon and Fusarium species also cause superficial fungal infection, but also may be considered an invasive pathogen that may cause a systemic infection [3,4].Dermatophytosis: Dermatophytes are fungi that invade keratinized structures of humans and animals producing a condition called dermatophytosis or, more commonly, tinea [5,6]. These fungi belong to three main genera Trichophyton, Microsporum and Epidermophyton, of these T. rubrum is the most prevalent species worldwide [7,8]. The mechanisms of pathogenicity of these fungi are not yet well understood. There are several studies focusing on keratinolytic proteases (keratinases) produced by dermatophytes, but it is not known how these fungi regulate the use of these proteases to obtain nutrients from the stratum corneum substrate they invade, and whether there are additional roles of these proteins in adhesion and immunomodulation [9].To establish the infection, the contact of arthroconidia or hyphal fragmens with the host skin is essential. The fungi express spe...