Mycology Flashcards
What are the dimorphic fungi?
Histo/Blasto/Cocci/Paracocci
Penicillium
Sporothrix
Chromoblastomycoses broadly
Fungal culture media
Nonselective: SAB, BBHI,
Selective: Mycosel (contains cyclohexamide), birdseed (stains phenol oxidase producers)
Fungal special stains
PAS - Nonselectively stains cell walls GMS - As above Mucicarmine - Crypto, rhinosporidium Fontana-masson - Crypto & other melanin producers India ink - Crypto
Calcofluor white: Chitin/cellulose, nonspecific
Lactophenol cotton blue: Wet preps, nonspecific
Histoplasma
Bird/bat guano. Necrotizing granulomas. Intra-macrophage.
Mold: Tuberculated microconidia (studded wheel)
Yeast: 2-4uM narrow budding
Urine antigen test available
Blastomyces
Mold: Pear-shaped (lollipop) conidia
Yeast: 8-20um double-walled, broad-budding
Coccidioides
Note: Immitis and posadasii are identical.
Mold: Barrel-shaped arthroconidia. DO NOT CULTURE.
Yeast: 50um spherule with endospores (mucicarmine-negative)
Rhinosporium
India, waterborne, mass-forming. Actually a parasite.
200um spherules with endospores (mucicarmine+)
Paracoccidioides
Brazil!
Mold: Pear-shaped conidia
Yeast: 10-20um mother-daughter cysts (Mariner wheel)
Eumycotic mycetoma
Mass-forming cutaneous lesion of usually black molds. Traumatic inoculation. “Madura foot”
Usually actinomyces (clumps of filamentous bacteria) or pseudallescheria (pear-shaped conidia).
Chromoblastomycosis
Subcutaneous infection with dematiaceous fungi (melanin-producers). Granulomatous. `
Usually Fonsecacea, phialophora, or cladosporium.
Yeast: Copper/medlar bodies. Large, septated/multicellular.
Sporothrix
Rose-thorn traumatic inoculation. Lymphangitic spread with buboes.
Mold: Daisy-wheel rosetting conidia.
Yeast: 2-5uM “cigar bodies”
Lobomyces
Keloidal verrucae.
Chains of globose cells.
Cannot be cultured.
Fusarium
Mold: “Banana”/canoe-shaped conidia. In tissue, appears to have swollen hyphal varicosities.
Candida (species!)
Albicans: Most common. Forms germ tubes (CORNMEAL AGAR)
Glabrata: Elderly. Resists fluconazole. No germ tubes. Trehalose assimilation.
Krusei: Resists fluconazole. No germ tubes.
Auris: Multidrug resistant.
Parapsilopsis: Children.
Triphasic morphology with pseudohyphae. May speciate with FISH or biochemical ID panels, or sequencing. UREASE NEGATIVE
Tinea versicolor
Malassezia furfur: Lipophilic organism, only grows with oil. Associated with IV lipids, catheters.
“Spaghetti & meatball” morphology. 2-4um yeast. Urease+
Microsporum
Microsporum canis: Dogs. Macroconidia with tapered ends.
Microsporum gypseum: Rare. Macroconidia with rounded ends.
Trichophyton
Rubrum: Feet, nails. Overall most common dermatophyte.
Tonsurans: Scalp
Microconidia (no macroconidia), “birds on a wire”
Epidermophyton floccosum
Beaver-tail macroconidia
Cryptococcus
Neoformans mainly (Gattii emerging). Bird guano, ubiquitous in soil. Cyclohexamide sensitive.
Yeast only. 2-20uM (variable!). Thick capsule, mucoid colonies.
Mucicarmine, Fontana-Masson.
Hyalohyphomycoses
Tissue infection by hyaline hyphal fungi.
Includes ASPERGILLUS, fusarium, paecilomyces.
Do not try to speciate unless fruiting bodies are present (rare, requires airspace)
Phaeohyphomycoses
Tissue infection with black molds (melanin producing)
Includes alternaria, curvularia, pseudallescheria, scedosporium.
Brown-red. Do not try to differentiate on H&E.
Alternaria
Black mold (pigmented). Inhibited by cycloheximide
Hand-grenade or honey-wand conidia.
Common environmental allergen. Seen in pap smears.
Curvularia
Black mold (pigmented)
Boomerang rounded conidia.
Pseudallescheria
Black mold (pigmented)
Pear-shaped conidia. Nondescript.
Zygomycetes
Rhizopus: Most common, has nodal rhizomes.
Mucor: Next most common, has no rhizomes.
Absidia: Rare, has internodal rhizomes.
Rapid growers (“lid-lifters”). Mince, do not grind.
Urease positive fungi
Cryptococcus
Malassezia
Aspergillus - Diagnosis
Rarely found in blood culture.
Galactomannan immunoassay
Penicillium marneffei
Southeast asia. Opportunist.
In plate: Red diffusible pigment.
Mold: Slender “skeleton-hand” phialide & conidia
Aspergillus species
Fumigatus: Green. Uniseriate phialide, conidia growing “up”. 45C growth. Cyclohexamide sensitive.
Niger: Black. Full circumference, black conidia.
Flavus: Yellow.
Terreus: Brown.
Syncephalastrum racemosum
No phialides
