Subcutaneous and Systemic Mycoses Lecture

Comprehensive practice flashcards covering subcutaneous and systemic mycoses, yeast identification, and opportunistic fungal pathogens as described in the lecture notes.

Subcutaneous Mycoses

Fungal infections that penetrate the epidermis and the dermis to infect deeper tissues, often resulting from traumatic skin puncture from thorns or vegetation.

Saprobe

An organism, especially a fungus, that lives on decaying organisms; also referred to as a saprotroph or saprophyte.

Chromoblastomycosis

A subcutaneous mycosis caused by dematiaceous fungi characterized by verrucoid lesions and the histological presence of muriform cells or "copper pennies."

Muriform cells

Also called sclerotic bodies or "copper pennies," these are dark-colored, septate cells with perpendicular septations characteristic of Chromoblastomycosis.

Mycetoma

A chronic, suppurative, and granulomatous subcutaneous mycosis that is destructive of contiguous bone, tendon, and skeletal muscle, often featuring draining sinuses and colored granules in pus.

Actinomycotic mycetoma

A form of mycetoma resulting from infection with aerobic actinomyces such as Nocardia, Actinomadura, and Streptomyces.

Sporotrichosis

A subcutaneous infection caused by Sporothrix schenckii, often acquired through trauma from thorny plants and typically spreading along cutaneous lymphatic channels.

Dimorphic fungus

A fungus that exhibits both a yeast phase (invasive phase in host tissue at $35^\text{o}\text{C}$ to $37^\text{o}\text{C}$) and a mycelial phase (saprophytic phase at $25^\text{o}\text{C}$ to $30^\text{o}\text{C}$).

Phaeohyphomycosis

Infections caused by dematiaceous (darkly pigmented) fungi with septate hyphae, excluding cases specific to chromoblastomycosis and mycetoma.

Phialophora verrucosa

A cause of chromoblastomycosis known as the "shallow cup bearer" due to its flask-shaped phialides with collarettes that resemble a vase of flowers.

Exoantigen testing

A serological method for identifying dimorphic fungi where soluble antigens extracted from mycelial elements are reacted with homologous fungal antibodies.

Blastomyces dermatitidis

The causative agent of Blastomycosis (Gilchrist’s disease), appearing in tissue as round to oval yeast cells with thick walls and broad-based, single budding.

Coccidioides immitis

A highly infectious fungus that causes Valley Fever, characterized by the formation of large, thick-walled spherules containing endospores in tissue.

Histoplasma capsulatum

A fungus saprobic in soil enriched by bird or bat droppings that causes infections acquired through inhalation; small yeast cells may be seen within monocytes or neutrophils.

Paracoccidioides brasiliensis

A fungus causing chronic granulomatous disease, characterized by multiple budding yeast cells that resemble a "mariner's wheel."

Penicillium marneffei

A dimorphic fungus that causes systemic penicilliosis in immunocompromised hosts, often isolated from the intestines of the Bamboo rat in Southeast Asia.

Blastoconidia

Asexual fungal spores produced through budding from a mother cell without separation.

Germ tube

A hyphal-like extension of a yeast cell with no constriction at the point of origin; produced by Candida albicans in sterile serum within $1$ to $3$ hours at $35-37^\text{o}\text{C}$.

Chlamydoconidia

Round, thick-walled spores produced by C. albicans and C. dubliniensis that function as organs of perennation.

Cryptococcus neoformans

An encapsulated yeast associated with bird droppings that can cause meningitis; visualized via India Ink preparation or capsular antigen testing.

Rhodotorula

A yeast found in human skin and the environment that produces orange or orange-red pigments and is Urease positive.

Geotrichum candidum

The agent of geotrichosis, characterized by true hyphae segmenting into rectangular arthroconidia that may show a "hockey stick" appearance.

Zygomycetes

A group of rapidly growing molds (including Rhizopus and Mucor) known as "lid lifters," featuring branching, ribbon-like, non-septate hyphae.

Aspergilloma

A "fungus ball" consisting of a tangled mass of Aspergillus hyphae that typically grows in pre-existing lung cavities.

Dematiaceous

A term for fungi that produce melanin in their cell walls, giving them a characteristic brown or black color.

Niger Seed Agar

A specialized medium used to identify Cryptococcus neoformans by its production of maroon to brown-black colonies through phenol oxidase activity.