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62 Cards in this Set

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Describe the 2 broad groups of fungi
Yeast: Single cells; round; reproduce by budding or fission

Mold: Germinate to branching fibers (hyphae); ends of hyphae have round forms that are NOT yeast but conidia, or spores

Dimorphic species are coded as molds
Name the 5 phyla of the kingdom Fungus: (and their corresponding sexual spores)
Ascomycetes (ascospores)

Basidiomycetes (basidiospores)

Zygomycetes (zygospores)

Chytridiomycetes or chytrids (oospores) (not a human pathogen)

Fungi Imperfecti (asexual)
Name the fungus
Candida albicans.

On cornmeal agar, chlamydospores are diagnostic for C albicans (see on tips).
Also can see blastoconidia arranged in dense clusters on pseudohyphae

On chromagar: C alb colonies are yellow-green to blue-green
Name the fungus
Candida.

Forms filamentous extensions (FEET or SPIDERS) on blood agar
You see a small creamy colony on culture. Next step?
Think yeast. Unicellular. Plate to cornmeal agar for initial categorization based on morphology. Some biochemical tests can help.

Growth on PFA & Mycosel: think candida --> germ tube test, + is albicans
Gr on PFA not mycosel: possible crypto, do urease test.

pfa = potato flake agar
mycosel = chloramphenicol & cycloheximide
You see a large fuzzy colony on culture. Next step?
Major considerations:
-Hyaline septate molds
-Pigmented/dematiaceous septate molds
-Aseptate molds
-Dimorphic fungi (will present as a mold. R/O with yeast conversion)

Consider rate of growth, type of hyphae, pigmentation, and type of sporulation (instant pattern recognition)
Rapid growers
ZYGOMYCETES ('lid lifters")

yeasts
C immitis
Aspergillus spp
Slow growers
Dimorphic fungi
Dematiaceous fungi

(>1 wk)
How to ID a dimorph?
Must demonstrate capacity for conversion
Grow as mold at 25-30C
Grow as yeast 37C (TISSUE FORM)
Some need coaxing (H caps - BHI; B dermatitidis - BHI; C immitis never converts)

Exoantigan test largely replaced conversion tests. Performed on culture.
Name the fungus
Aspergillus fumigatus
Aspergillus fumigatus

-Rapid grower
-Cx: Blue-green with white apron
-Morph: Conidia terminate in swollen vesicle
A fumigatus: single row of phialides (vs penicillium - branches; vs A terreus - double row)
A niger: heavy pigment
A flavus: lollipop. circumferential phialides
Aspergillus niger

- Cx: black on one side, yellow on other vs dematiaceous fungi - black both sides
Aspergillus terreus

- cinnamon colonies
- Double row of phialides (vs A. fumigatus - single row)
Aspergillus flavus

Circumferential phialides
LOLLIPOP
Aspergillus
Penicillium
Geotricum
Trichophyton

Microsporum
Epidermophyton
Rhizopus
Aspergillus: Major diseases & identifying characteristics
Usually A. fumigatus
-ABPA (allx bronchopulm asp - colonizes airway and elicits allx response. Dx serology IgE)
-IBPA (invasive bp asp - invades. immunocompromised host)
-Aspergilloma (non-invasive. upper lobes)

ID:
- Tissue: hyaline septate mold (i.e. clear with hyphae), 45 degree branching (not specific)
- Cx: Rapid growth, colonies with distinct margin & white apron, FRUITING HEADS
What grows on Mycosel?
Dimorph or dermatophyte (slow growers)

Mycosel contains cycloheximide that inhibits contaminants, as well as Zygomycetes, Aspergillus, and Crypto.
dermatophyte chart
Candida
Cryptococcus

May mimic broad/narrow based budding
** Characteristic variation in size! **
3-15 um
Cryptococcus

India ink preparation

Lack of staining = CAPSULE
Malassezia

Causes tinea versicolor & seborrheic dermatitis

Lipophilic

SPAGHETTI & MEATBALL hyphae

BOTTLE SHAPED YEAST ~wobbles
Microsporum

(this is M. gypseum)

Pear-shaped macroconidia

M.gypseum: flat tan cx.
M.canis: fluffy; yellow reverse cx. Tinea capitis.
Trichophyton mentagrophytes

causes athletes foot
colonies: white fuzzy on front, brownish on back

BIRDS ON A FENCE (characteristic microconidia; can have cigar-shaped macroconidia)
(more jax-like than T rubrum)

Dermatophyte (with microsporon, epidermophyton)
BIRDS ON A FENCE

Trichophyton rubrum

#1 cause jock itch, athlete's foot, onychomycosis
(dermatophyte)
(reddish colonies)
Microsporum canis

Dermatophyte (along with trichophyton & epidermophyton)

Spindle-shaped macroconidia with pointed ends & transverse septa

Causes SCALP infection (tinea capitis)

Microsporon do NOT infect nails
Microsporum gypseum

Dermatophyte

Oval-shaped macroconidia with BLUNT ends (vs M canis) and transverse septa
Epidermophyton floccosum

Dermatophyte
Club-shaped macroconidia with transverse septa; NO microconidia
Morphology of aspergillus vs. penicillium
Aspergillus: Toilet brush: Has a circle, then spikes

Penicillium: Paintbrush: Bristles emanate directly from surface
Penicillium

"paintbrush"

hyaline mold (~aspergillus, fusarium)
GREEN COLONIES
common bread mold. ubiquitous
Fusarium

PINKISH Hyaline mold (~aspergillus, penicillium)
Unique to hyaline filamentous molds in that produces micro & macro conidia (micro are small and ~acremonium; macro are canoes)

May cause opportunistic infection
Important plant pathogen (the banana killer!)
Histoplasmosis of the lung

2-5um yeasts, narrow-based budding, seen in tissue within histiocytes

OH & MS river valleys
GUANO
Dimorphic fungus
Slow grower
Histoplasmosis


-Grows as yeast in tissue; mold at <30C

Hyaline septate mold with lollipop-like smooth microconidia & spiked macroconidia (in more mature colonies. Early may mimic birds on a fence)

Grows within histiocytes in tissue, 2-5um, narrow based budding. necrotizing granulomas.
Blastomyces dermatitidis

8-12um

BROAD BASED BUDDING

MS & OH river valley; dogs.

lung --> skin & bones
Blastomyces

LOLLIPOP CONIDIA
DDx for LOLLIPOP CONIDIA in fungal culture:
Blastomyces dermatitidis
Histoplasma capsulatum (older colonies develop spiked macroconidia)
Paracoccidioides
Scedosporium & Chrysosporium
Sepedonium (~histopl)
Sporothrix schenkii

2-5um elongated cigar-shaped yeasts with NARROW budding

Purulent background

Rose thorn puncture --> subcutaneous mycosis
Sporothrix schenckii

Dimorphic fungus, NOT spread by inhalation (rose thorn puncture)

Mold form: hyphae with DAISY conidia
Dimorphic fungus; more rapid growth (7d)
Coccidioides immitis

Granulomas with large 50-200um spherules with thick walls; enclose tiny 2-5um endospores

California - Valley fever

DDx: Rhinosporidium (nasal lesion), P wickerhami (olecranon bursitis). Endospores may look like histopl but DO NOT BUD
Coccidioides immitis

Barrel-shaped arthroconidia
Rapid growth (7d) vs other dimorphs

Inhaled
What blood group is more susceptible to infection with coccidoides? What are other risk factors?
Blood group B

Third trimester pregnancy

Immunosuppression
Dimorph; v slow growth (10-30d)
Paracoccidioides braziliensis

Tissue: diagnostic 10-15um yeast with circumferential budding = MARINER'S WHEEL

Cultures: identical to blastomyces (lollipop conidia)

Central & S America. Inhaled spores --> dissemination to reticuloendothelial system, bowel, liver.
- hyaline mold
- slow growth (unlike other hyalines)
Acremonium

- plant & soil; may be opportunisic infection
- source of cephalosporins

Filamentous hyphae with simple 1-celled conidia
Name the hyaline molds
Aspergillus
Penicillium
Fusarium
Acremonium
dermatophytes
...
Name the dematiaceous molds
Alternaria
Bipolaris
Cladosporium
Exophiala
Fonsecaea
Wangiella
Phialophora

(pigmented, slow-growing)
More commonly cause allergic fungal sinusitis vs aspergillus
Name the dermatophytes
Trichophyton
Microsporon
Epidermophyton
Name the zygomycetes (aseptate molds)
Mucor
Rhizomucor
Rhizopus
Cunninghamella
Absidia
Alternaria

Dematiaceous mold

Large conidia with ALTERNATING transverse & longitudinal crosswalls
Bipolaris

(a dematiaceous mold)

Bipolar = can form germ tubes from both poles

Colonies: white --> black. Rapid. Woolly.

Knobby (GENICULATE) zigzag conidia on microscopy
Curvularia

(a dematiaceous mold)

Woolly gray black colonies. rapid.
Geniculate (knobby) conidia with 4 cells (3rd cell larger & curved)

Cause of sinusitis, keratitis, pulm infxn, dissemination
Name this skin condition & the most common pathogen associated with it
Chromoblastomycosis
- Chronic skin infection of the legs
- Tropical regions

Most common cause is: Fonsecae (a dematiaceous mold). KOH skin scrapings show COPPER PENNY bodies
Absidia

(zygomycete)

Woolly, rapid.

Hershey's kiss columella; Pear-shaped sporangia
Rudimentary rhizoids

Growth 25-42C. Can be human pathogen, causing pulmonary, rhinocerebral, or disseminated infection.
Rhizomucor

Zygomycete (woolly, fast)

short sporangiophores; tufts; branched. Some rhizoids.

Growth up to 55C
Yeast colonies growing on culture; germ tube test is positive. Possibilities?
Candida albicans
Candida dublinensis

(Must VITEK if sterile site)
Hyaline molds characterized by production of conidia in chains
Penicillium sp
Paecilomyes sp
Scopulariopsis sp
Hyaline molds producing conidia in clusters
Acremonium sp
Fusarium sp
Gliocladium sp
Trichoderma sp
Paecilomyces

Long tapered phialides
Oval irregular conidia

DDX: PENICILLIUM (but never green)
-blunt phialides
Scopulariopsis

radial rugae

chains of conidia

soil; can cause onychomycosis
Penicillium

Characteristic green
Fusarium

Characteristic pink color

Woolly
Not growing on mycosel
White yeast not growing on mycosel: Think cryptococcus. Candida albicans grows on mycosel. Do germ tube test & urease.
Name some candida non-albicans
C. glabrata: UTIs. Slower growth (72h). Budding yeast, NO pseudohyphae

C. krusei: resistant to ketoconazole. matchstick blastoconidia
C. dubliniensis: res to fluconazole. Very ~albicans - must ID on VITEK