Fungal Candidiasis and Its Role in Superficial and Systemic Infections

External parts of the body such as the skin, hair and nails are susceptible to infections caused by this yeast because it possesses two types of enzymes: protease and keratinase. These enzymes facilitate the yeast's ability to infect the keratinised outer layer. The incidence of fungal infections has increased in recent years due to increasing resistance to antifungal agents and the limited availability of antifungal treatments, which are often associated with numerous side effects. Yeasts belong to important genera classified in the phylum Deuteromycotina (Imperfect Fungi). They are single-celled, eukaryotic organisms that reproduce asexually by budding. They lack a sexual phase and have oval cells with a diameter of 3 to 6 micrometres. Yeasts can occur as single cells or form pseudohyphae in host tissues where they develop germ tubes - a precursor to invasion of host tissues. Colonies are smooth, soft, white to yellowish in colour and often give off a yeasty odour. Due to the absence of chlorophyll, yeasts exhibit nutritional heterogeneity and dimorphism, allowing them to grow in either hyphal or yeast form depending on environmental conditions. The species Candida albicans is one of the most important pathogenic yeasts responsible for candidiasis, a fungal infection that can be primary or secondary and is caused by different species within the genus Candida. The infection can be acute, subacute or chronic, causing localised lesions in the mouth, throat, skin, vagina, fingers, nails and trachea. In some cases, the infection can spread systemically, affecting the lungs and gastrointestinal tract (Dignani et al, 2009).