Mycology Review: Yeasts, Molds, Dermatophytes, and Subcutaneous Mycoses (Fill-in-the-Blank)

Fill-in-the-blank flashcards covering key concepts from the lecture notes on yeasts, molds, dermatophytes, and subcutaneous mycoses.

yeasts

Fungi grow in two forms: and molds.

2 to 10

Hyphae are branching cylindric tubules varying in diameter from μm.

downward

Aerial Mycelia extend to the surface; Vegetative Mycelia extend .

fission

Mode of reproduction in yeasts includes budding and .

fuzzy/wooly

Molds often have a appearance.

rarely

Hyphae of Mucorales are septated.

conidia

The most helpful phenotypic features for identifying molds are the ontogeny and morphology of the asexual spores, or .

moose antlers

Antler Hyphae / Favic Chandelier are branching tips resembling .

club

Racquet Hyphae are shaped.

tight

Spiral Hyphae show coils.

comb-like

Pectinate Bodies are structures.

root

Rhizoids are -like structures.

Aseptate

Septate Hyphae have frequent cross-walls; Hyphae lack septa.

irregular

Sparsely Septate Hyphae have few cross-walls at intervals.

non-pigmented

Pigmentation of hyphae is based on melanin on the cell wall: Hyaline (moniliaceous) hyphae are pigmented; Phaeoid (dematiaceous) hyphae are darkly pigmented.

tissue phase (spherule)

Dimorphism is the ability of a fungus to exist in two forms depending on growth condition; at 37°C with increased CO2 the growth form is the (tissue) phase.

mycelial/mold

Room temperature (22–25°C) promotes the mold form or phase.

Exophiala

Polymorphism means both yeast and mold forms occur in the same culture; example species: spp.

phialoconidia

Phialides are vase-like structures that produce .

annelloconidia

Annellides are ringed structures that produce .

fertile

Arthroconidia are formed by fragmentation of hyphae.

sexually; asexually

Teleomorph refers to fungi reproducing ; Anamorph is .

anamorph

Synanamorph means more than one is present for the same teleomorph.

Fungi Imperfecti

Deuteromycota is another name for the group known as .

asexual

Mucorales reproduce primarily by an ; sporangiospores.

ascospores

Ascomycota produce sexual spores called within a sac called an ascus.

basidium

Basidiomycota produce sexual spores on a club-shaped .

21

Sabouraud’s dextrose agar is a traditional mycological medium with pH 7.0; incubation for fungal cultures is typically days at 30°C.

non-sterile

Inhibitory Mold Agar (IMA) contains antibiotics such as Gentamicin, Chloramphenicol, and Cycloheximide to suppress bacteria and saprophytic molds, allowing isolation of clinical fungi from specimens.

lipids

Malassezia furfur causes Pityriasis versicolor and is a lipophilic yeast requiring in the medium for growth.

Malassezia furfur

Direct microscopy of scrapings treated with 10–20% KOH is used for diagnosing infections caused by ; Malassezia is lipophilic.

(color not specified in notes)

Wood’s lamp examination can aid in the diagnosis of Malassezia infections by causing characteristic fluorescence.

Malassezia furfur

Pityriasis versicolor is caused by (Malassezia furfur).

Trichosporon

White Piedra is caused by species of the genus (e.g., Trichosporon spp.).

Piedraia

Black Piedra is caused by hortae.

Hortaea werneckii

Tinea nigra is caused by (formerly Hortaea werneckii).

Trichophyton; Microsporum

Tinea capitis has two forms: gray patch ringworm (ectothrix) and black dot ringworm (endothrix); causative agents include species of the genus and .

Chromoblastomycosis

Favic Chandelier hyphae are diagnostic features seen in Chromoblastomycosis or other infections?

copper pennies

Chromoblastomycosis is caused by dematiaceous fungi such as Fonsecaea compactum, F. pedrosoi, Phialophora verrucose, Cladophialophora carrionii, and Rhinocladiella aquaspersa; a key histopathologic finding is the presence of sclerotic bodies, also called .

extremities

Sporotrichosis is a chronic mycosis of the skin and subcutaneous tissues caused by traumatic inoculation and is usually confined to the .

Anthropophilic

Dermatophytes are categorized by habitat into Geophilic (soil), Zoophilic (animals), and (humans).

dermatophytosis (tinea corporis)

Dermatophyte infections of the glabrous skin (body) are collectively referred to as ; common sites include the trunk, limbs, and groin.

ectothrix; endothrix

The species causing tinea capitis can show either ectothrix infection (hair shaft exterior) or endothrix infection (hair shaft interior); the former is called and the latter .

Trichophyton schoenleinii

The dermatophyte causing tinea nigricans (hair-bearing skin) is often associated with the family of fungi that include Tinea favosa/favus; the causative agent for favus is .

Sporotrichosis

Subcutaneous mycoses include chromoblastomycosis, eumycotic mycetomas, phaeohyphomycosis, and ; the typical organism for sporotrichosis is Sporothrix schenckii.

sporotrichoid spread

Sporotrichosis is usually acquired by trauma and presents as nodular lesions along lymphatic channels, termed lymphocutaneous .