Mycosis - Introduction, Classification, Superficial, Subcutaneous, Systemic, Opportunistic
Introduction to Mycosis
Mycosis is a human infection caused by fungus. Pathogenic fungi may or may not produce toxins and regularly induce hypersensitivity to the host and their chemical constituent.
Since fungi are soil saprophytes, their ability to adapt to the host tissue environment and elicit diseases is extremely variable.
Mycoses are not usually transmitted sexually like viral, bacterial, or parasitic diseases. Balanoposthitis, caused by Candida spp. May, however, be transmitted by sexual contact.
Clinical classification of mycosis
Based on clinical manifestations, mycosis can be classified into the following types:
Superficial or cutaneous mycosis
Subcutaneous mycosis
Systemic mycosis
Opportunistic mycosis
Miscellaneous mycosis
Superficial or cutaneous mycosis
Mycosis of keratin of skin, nails, mucosa, and hair shaft is called superficial or cutaneous mycosis. These infections are common and troublesome.
It is strictly a surface infection where no living tissue is invaded. As deeper tissue is not infected, host cellular response is not observed. Pathological changes are elicited.
Eg: Exophiala weerenckii (Tinea Nigra)
Piedraia hortae (Black piedra)
Trichosporon beigelii (White piedra)
Candida albicans (Candiasis of skin, mucous membrane, nails)
Microsporum audouinii (Tinea capitis)
Microsporum canis (Tinea capitis)
Trichophyton rubrum (Tinea pedis, Tinea unguium, Tinea cruris, Tinea manum, Tinea barbae)
Trichophyton mentagrophytes (Tinea pedis, Tinea unguium, Tinea corporis)
Trichophyton verucasum (Tinea corporis)
Epidermophyton flocossom (Tinea pedis, Tinea cruris, Tinea manum, Tinea barbae)
Subcutaneous mycosis
Subcutaneous mycosis are chronic, localized infection of the skin or cutaneous tissue after a traumatic implant. Such infection may progress into local diseases resulting in tissue destruction and sinus formation. As mycosis progresses, the lesions may spread slowly via lymphatics.
Eg: Sporothrix schenckii (Sporotrichosis)
Phialophora spp. (Chromoblastomycosis)
Cladosporium spp. (Chromoblastomycosis, Phaeophyphomycosis)
Exophiala spp. (Phaeophyphomycosis, Mycotis mycetoma)
Wangiella spp. (Phaeophyphomycosis)
Bipolaris (Phaeophyphomycosis)
Pseudallescheria spp. (Mycotis mycetoma)
Madurella spp. (Mycotis mycetoma)
Acermonium spp. (Mycotis mycetoma)
Rhizopus spp. (Mucor mycosis)
Mucor spp. (Mucor mycosis)
Rhizomucor spp. (Mucor mycosis)
Rhinosporidium seeheri (Rhino sporidiosis)
Loboa loboi (Lobomycosis)
Systemic mycosis
Systemic mycosis is caused by dimorphic fungal pathogens which are normally soil fungi. Such infections are caused by inhalation of the spores and are mostly asymptomatic. These fungi are geographically restricted.
The primary site of infection is usually pulmonary due to inhalation of spores/conidia. Although lung infections are self-limited, in symptomatic cases, dissemination may occur to any organ. Cryptococcosis can be seen in the central nervous system (CNS).
Eg: Cryptococcus neoformans (cryptococcosis)
Blastomyces dermatitisis (blastomycosis)
Coccoidiodes immitis (coccidiodomycosis)
Paracoccidioides brasiliensis (paracoccidioidomycosis)
Histoplasma capsulatum (histoplasmosis)
Opportunistic mycosis
Opportunistic mycosis is found in patients with compromised immune systems – either by disease or by therapy.
Eg: Candida albicans (candiasis)
Aspergillus fumigatus (aspergillosis)
Geotrichum spp. (geotrichosis)
Cryptococcus neoformans (cryptococcosis)
Pneumocystis carinii (pneumocytosis)
Penicillum marneffei (Penicilliosis)
Pseudallescheria boydii (Pseudallescheriasis)
Miscellaneous mycosis
Miscellaneous mycosis includes:
Otomycosis – fungal infection in the ear canal
Osteomycosis
Keratomycosis – a fungal infection of the corneal stroma