Question

8. Define the term mycosis, and differentiate between systemic mycosis, subcutaneous mycosis, and superficial mycosis. If a person contracted a fungal disease that was caused by the group of fungi known as dermatophytes, what type of mycosis would this be? Why is this group of fungi able to cause this type of infection and how it is usually transmitted?
   

Answer 1

• Mycoses refers to the infection caused by fungi ( fungal infection) in animals (also including humans).
• Localized colonization of skin by fungus or fungal spore inhalation are most common causes of mycosis.
• Fungal infections affecting outermost layer of skin, epidermis (surface) of hairs and nails are known as superficial or cutaneous mycosis, caused by Tinea versicolor, T. nigra, T. corporis, Masalassezia furfur.
• Heterogeneous group of fungi infect subcutaneous tissue of skin, causing subcutaneous mycoses, with causative agents prevalent in soil, organic material and leaves. Cladophialophora carrioni(Chromoblastomycosis), Wangiella dermatitidis(pheohypomycosis), Sporothrix schenckii (sporotrichosis) are some examples of subcutaneous mycoses.
• When internal organs are infected by fungi, systemic mycoses is caused which in extreme conditions causes multiple organ failure. Immunocompromised patients are more likely to develop systemic mycoses. Causative agents of systemic mycoses include : Histoplasma capsulatum(histoplasmosis), Coccidioides immitis(coccidioidomycosis), and Blastomyces dermatitidis(blastomycosis).
• Dermatophytes also known as Tineas are fungal species which infect the keratinized tissues i.e. cutaneous mycosis usually caused by Tinea cruris and Tinea pedis.
• Dermatophytes colonize skin and keratin, pH of skin activates keratinases and proteases which result in release of polypeptides, which are further cleaved into amino acids by peptidases which provide nutrition to growing fungus and alkalization for prevalence of infection.
• Dermatophyte infection can be transmitted by contaminated soil, brushes and Combes (fomites) and coming in contact with infected individuals.