Adv. Microbiology Unit 7 - Mycology Introduction and Yeasts

Long strands of fungal cells.

hyphae

Hyphae found above the surface of an inoculated media.

aerial

__________ fungi exists as a mold at ___________°C and as a yeast at __________°C.

dimorphic; 22-25; 37

Hyphae found below the surface of an inoculated media.

vegetative

Term to describe lightly pigmented hyphae.

hyaline

Term for hyphae with cross-walls.

septate

Term for hyphae without cross-walls.

aseptate

Term to describe darkly pigmented hyphae.

dematiaceous

Term for fungi that reproduce sexually.

fungi perfecti

Term for fungi that reproduce asexually.

fungi imperfecti

This reproductive structure has a 'budding' appearance.

blastoconidia

This reproductive structure has thick-walled structures for food storage.

chlamydoconidia

This reproductive structure involves the nuclei of a male cell passing through a bridge into a female cell.

ascospores

This reproductive structure appears as 'vase-like structures'.

phialoconidia

This reproductive structure appears as barrel-shaped cells that align single file.

arthroconidia

This reproductive structure is large and septated.

macroconidia

This reproductive structure is smaller and aseptated.

microconidia

This reproductive structure is formed by the fusion of compatible hyphae using clamps

basidiospores

Term for a sac containing sporangiospores.

sporangium

Term for the 'roots' associated with sporangiospores.

sporangiophores

This reproductive structure appears as thin stalks with sacks at their ends.

sporangiospores

This reproductive structure appears as two hyphae extending 'arms' toward eachother.

zygospores

What are the three reproductive structures for fungi that reproduce sexually.

zygospores/ascospores/basidiospores

What are the two basic nutrient agars used for culturing suspected fungal specimens?

SAB/SDA

Which agar contains extra nutrients intended for culturing suspected fungal specimens?

SABHI

This agar has added antibiotics to help inhibit opportunistic pathogens when culturing for suspected fungal specimens.

SAB C&C

In a positive result, dermatophyte test medium changes from ___________ to ____________.

yellow; red

This media is used to identify reproductive structures for term tube negative organisms.

cornmeal agar

What is the optimal temperature for incubating fungal cultures?

30C

Media inoculated with suspected fungal specimens must be held for ___________ before discarding?

6 weeks

What test would you perform if you suspect a fungal infection in CSF?

india ink

What fungal species can cause meningitis in immunocompromised patietns?

cryptococcus

When looking for hairs suspected of fungal infections, select hairs that __________ or appear ___________.

fluoresce; broken or scaly

Before doing a direct exam on cutaneous specimens suspected of fungal infections, you should treat the specimen with _________.

KOH

How does yeast appear on a wet mount?

refractile

What kind of direct exam would you use for a genital discharge specimen suspected of fungal infection?

wet mount

What type of direct exam should you use on wounds/lesions suspected of fungal infection?

gram stain/calcofluor

What is the purpose of phenol in an LPCB?

kills any organisms present

What is the purpose of lactic acid in an LPCB?

preserves fungal structures

What is the purpose of cotton blue in an LPCB?

stains the chitin in fungal cell walls

LPCB should be performed on __________ organisms.

isolated

How do yeast appear in a gram stain?

gram positive (2-3X larger than GPC)

A tech should examine a fungal media for growth at least __________.

weekly

Term used to describe a fungal colony with high mycelium

cottony

Term used to describe a fungal colony with low mycelium

velvety

Term used to describe a fungal colony with flat, crumbly mycelium.

granular

Term used to describe a fungal colony with a smooth surface.

glabrous

Term used to describe a fungal colony that has deep furrows radiating from the center of the colony.

rugose

Term used to describe a fungal colonythat has a 'button-like' elevation in the center.

umbonate

Term used to describe a fungal colony that has a wrinkled surface.

verrucose

A ____________ uses LPCB to view reproductive structures separated on a slide using a needle/loop.

tease mount

The germ tube test determines the presence/absence of __________.

C. albicans

What is the reagent for the germ tube test?

rabbit serum

Describe the appearance of a positive germ tube test result.

parallel sides/aseptate/no constriction point at site of attachment

Fungi can be differentiated using carbohydrate _________.

assimilation

What is the most commonly isolated yeast?

Candida albicans

This species of yeast produces single or small clusters of blastoconida on a cornmeal agar.

Candida tropicalis

What species of yeast can cause endocarditis or nail infectiosn?

Candida parapsilosis

This species of yeast produces single or short chains of blastoconidia on cornmeal agar.

Candida parapsilosis

This species of yeast is present in bird droppings and can be inhaled.

Cryptococcus neoformans

This species of yeast is india ink and urease positive.

Cryptococcus neoformans

This species of yeast produces round blastoconidia with a capsule.

Cryptococcus neoformans

How does Cryptococcus neoformans appear on a birdseed agar?

dark brown

This species of yeast produces arthroconidia on cornmeal agars.

Geotrichum candidum