Fungi - Key Terminology and Concepts

A set of vocabulary-style flashcards covering major fungal structure, reproduction, classification, pathogens, disease types, and diagnostics based on the provided lecture notes.

Fungi

Eukaryotic organisms in their own kingdom; have a thick cell wall with chitin, glucans, mannans and glycoproteins; include yeasts and molds; cause mycoses (fungal infections).

Eukaryotes

Organisms with a true nucleus and membrane-bound organelles; fungi are eukaryotes.

Chitin

A structural polysaccharide in the fungal cell wall, contributing to rigidity.

Glucans

Polysaccharides in the fungal cell wall that contribute to structure and integrity.

Mannans

Polysaccharides in the fungal cell wall involved in cell wall function.

Glycoproteins

Proteins with carbohydrate groups that are part of the fungal cell wall/membrane machinery.

Mycoses

Infections caused by fungi (yeasts or molds).

Hyphae

Tubular, branching filaments of fungal cells forming the body of most molds.

Septa

Cross-wwalls in hyphae; hyphal divisions that are typically porous.

Pseudohyphae

Hyphae-like filaments formed by chains of budding yeast cells that remain attached.

Mycelium

The vegetative network of hyphae that forms the body of a fungus.

Sporangia

Sporangia are sacs that produce spores in some fungi.

Spores

Haploid reproductive particles formed on hyphae or mycelium; can be produced sexually or asexually.

Sporangiophore

Hyphal stalk bearing sporangia (spore-producing structure).

Conidia

Asexual spores produced on conidiophores; can bud in clusters or chains.

Conidiophore

Hypha bearing conidia (where asexual spores form).

Germ tube

Outgrowth from a spore during germination; lacks constrictions at origin.

Anamorph

Asexual reproductive state of a fungus.

Teleomorph

Sexual reproductive state of a fungus.

Microconidium

Small asexual fungal spore.

Macroconidium

Large asexual fungal spore.

Yeasts

Unicellular fungi, usually reproduce by budding or fission; form smooth, creamy colonies.

Molds

Multicellular fungi with hyphae forming a mycelium and fuzzy colonies; produce spores.

Dimorphic fungi

Fungi that grow as molds at ~20°C and yeasts at ~37°C (temperature-dependent form).

Candida albicans

Common yeast species; opportunistic pathogen; can form pseudohyphae and cause candidiasis.

Cryptococcus neoformans

Encapsulated yeast; causes cryptococcosis and meningitis; detected by India ink and CrAg tests.

Malassezia furfur

Lipophilic yeast; causes pityriasis versicolor (tinea versicolor).

Aspergillus fumigatus

Mold with septate hyphae that branch at ~45°; opportunistic pathogen; some species produce aflatoxins.

Dermatophytes

Keratinophilic fungi causing superficial and cutaneous infections; genera include Trichophyton, Microsporum, Epidermophyton.

Trichophyton rubrum

A common dermatophyte species associated with tinea corporis, tinea pedis, and tinea unguium.

Microsporum canis

Dermatophyte often causing tinea capitis and other dermatophytoses.

Epidermophyton

Dermatophyte genus implicated in tinea infections, especially tinea cruris and pedis.

Tinea corporis

Ringworm of the body caused by dermatophytes (e.g., Trichophyton).

Tinea capitis

Ringworm of the scalp; commonly caused by Trichophyton or Microsporum species.

Tinea pedis

Athlete’s foot; dermatophyte infection of the foot.;

Tinea cruris

Jock itch; dermatophyte infection of the groin.

Pityriasis versicolor

Malassezia furfur infection causing hypo- or hyperpigmented patches on the trunk.

Wood lamp fluorescence

Fluorescence pattern used in dermatophyte identification: Trichophyton (yellow-green), Microsporum (partial blue-green), Epidermophyton (no typical fluorescence).

Histoplasma capsulatum

Dimorphic fungus causing histoplasmosis; often seen in soil with bird/bat droppings.

Blastomyces dermatitidis

Dimorphic fungus causing blastomycosis; ranges from cutaneous to systemic disease.

Coccidioides immitis

Dimorphic fungus causing coccidioidomycosis (valley fever) with spherules in tissue.

Paracoccidioides brasiliensis

Dimorphic fungus causing paracoccidioidomycosis, mainly in the Americas.

Sporothrix schenckii

Dimorphic fungus causing sporotrichosis (rose gardener’s disease).

Aflatoxins

Toxins produced by some Aspergillus species; potent carcinogens affecting liver.

Ergot alkaloids

Toxins produced by Claviceps purpurea; cause ergotism; historically linked to medieval outbreaks.

Amanitins

Toxins (amatoxins) in Amanita mushrooms; potent hepatotoxins causing severe liver injury.

Ergosterol

Fungal membrane sterol; target of many antifungal drugs (azoles, polyenes).

Squalene epoxidase

Enzyme in ergosterol synthesis; inhibited by terbinafine (allylamine class).

14-α-demethylase

Cytochrome P450 enzyme in ergosterol synthesis; inhibited by azole antifungals.

Sabouraud agar

Culture medium with low pH, selective for fungi; contains antibiotics to inhibit bacteria.

KOH prep

Microscopic method using potassium hydroxide to clear skin/hair samples for fungal elements.

India ink

Negative stain used to visualize capsules, especially Cryptococcus neoformans in CSF.

Gomori methenamine silver (GMS)

Histopathology stain that highlights fungal elements in black on green background.

Periodic acid–Schiff (PAS)

Stain that highlights fungal cell wall polysaccharides in magenta/pink.

Beta-D-glucan

Fungal cell wall component measured in serum; marker for invasive fungal infections.

Galactomannan

Fungal polysaccharide antigen used to detect Aspergillus infections (serology).

Cryptococcal antigen (CrAg)

Serum/CSF antigen test for Cryptococcus neoformans; supports diagnosis of cryptococcosis.

PCR

Molecular method to detect fungal DNA; useful but not universally standard in all settings.

Superficial mycoses

Fungal infections limited to outer skin, hair, and nails surface. (e.g., tinea versicolor, dermatophyte infections of skin/hair)

Cutaneous mycoses

Fungal infections of the skin, hair, and nails; typically dermatophyte infections.

Subcutaneous mycoses

Infections involving deeper skin and subcutaneous tissue, often after trauma.

Systemic mycoses

Fungal infections affecting internal organs and systems; can be disseminated.

Opportunistic mycoses

Fungal infections that mainly affect immunocompromised hosts.

Capsule

Protective polysaccharide capsule; notably in Cryptococcus neoformans, contributing to virulence.