Laboratory Diagnosis Of Fungi Flashcards by Iseoluwa Ojo

Collection of specimens:

Skin specimens - clean with _________ to remove dirt, oil and surface saprophytes.

Nails - cleaned with ________. It is Usually ______; need to be _______ before inoculating to media.

Hair - obtained from _______________ ; hair can be obtained by ______,______ , or with a _______. A ________ can be helpful in locating infected areas.

Body fluids - normal sterile collection procedures.

70% alcohol

70% alcohol ; clipped; finely minced

edge of infected area of scalp; plucking, brushing; sticky tape; Wood’s lamp

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Preparation of specimens for transport:

Hair & nails sent in a _________ , inside proper container.

Other specimens are usually sent _____ or ______

dry envelope

frozen; on dry ice.

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Packaging of specimens - must meet _____________.

Cultures must be on _____ media (not ____).

Inside labeling information: ______,_____,_______
Outside labeling - _______________

biohazard regulations

tubed; plates

patient ID, specimen source, suspected organism.

WARNING: POTENTIAL PATHOGEN

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Processing of specimen to recover fungus:
Body fluids -

CSF - should be ______ ; examine _____ _____scopically, then ________.

Pleural fluid, sputum, and bronchial aspiration - specimen must be _______ , as _____ would overgrow pathogens such as ________. The Specimens may be refrigerated up to _________

Gastric washings - same as for ______ fluids.

centrifuged; sediment; micro; inoculate media

fresh; saprophytes; H. capsulatum

2 hours.

pleural

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Direct examination of specimens:

Direct exam is required on any biological material sent to lab for fungus culture.

Examine for ____,______,_____,____,____

spores, hyphae, mycelial elements, budding yeast, mycotic granules.

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Direct examination of specimens:

Wet mount - good for ______; examination is done in _____ environment, so that ________ is minimal.

KOH - done on _____,_____,_____,_____,_____ specimens. KOH _____________ so fungal elements may be seen.

yeast

natural; loss of fragile structure

skin scrapings, hail, nails, sputum, vaginal

clears tissue cells

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Processing of specimen to recover fungus:
Body fluids - (continued)

Genito-urinary specimens - _______ specimen preferred; should be _____ and _______ on media.

Blood/bone marrow - _________ to _____ and _____

Wound abscess or drainage - culture _____ if actinomycosis is suspected.

Tissue specimens - examine for _____,______, or ______; mince _____cally, inoculate on media.

first morning ; centrifuged & inoculated

inoculate to BHI broth and BHI slant.

anaerobically

pus, caseous material or granules

asepti

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Staining

______________________ - very popular for quick evaluation of fungal structures; stains chitin in cell walls of fungi.

____________________ - stains polysaccharide in the cell wall of fungi.

_____________________ Stain - silver nitrate outlines fungi in black due to the silver precipitating on the fungi cell wall.

Lactophenol Cotton Blue

Periodic Acid - Schiff Stain (PAS)

Gomori Methenamine Silver

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With Periodic Acid - Schiff Stain (PAS), Fungi stain ______ with ____ nuclei.

pink-red

blue

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Staining
Stains used: (continued)

___________ Stain - extremely specific method of detecting fungi in tissues or fluids.
_________ Stain - good for initial differentiation of dimorphic fungi. Works well on sputum smears.

Fluorescent Antibody

Papanicolaou

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In Gridley Stain - Hyphae and yeast stain _______ or ____ . Tissues stain ________ and background is ______.

dark blue or rose

deep blue ; yellow

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Mayer Mucicarmine Stain - will stain capsules of Cryptococcus neoformans _________

deep rose.

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Gram Stain - generally fungi are gram _______; but ______ and _____ are gram variable.

positive

Actinomyces and Nocardia

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Staining
Stains used: (continued)

Acid-Fast Stain - used to differentiate the __________ from other ________

Giemsa Stain - used for _____ and ______ specimens.

India Ink - demonstrates the _______ of ________ in _____ specimens.

acid-fast Nocardia; aerobic Actinomyces.

blood and bone marrow

capsule of Cryptococcus neoformans; CSF

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Fungal Culturing:
Culture
______ media is used rather than _____ media.

Tubed

plated

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Fungal Culturing:
Culture
Tubed media is used rather than plated media.

Why

Less chance for _______
Less chance for ______.
Easier _______.

spore release into the environment.

dehydration

storage

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The agar in a tube is inoculated in a ________.

Preliminary identification is based on __________ on various media.

straight line

differential growth patterns

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Fungi culture media

__________ agar - classic medium, recommended for most studies.

Sabouraud’s dextrose

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Sabouraud’s dextrose agar with ______ which inhibits bacterial growth

chloramphenicol

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______ agar - a commercially produced agar containing chloramphenicol to inhibit bacterial growth, and _______ to inhibit saprophytic fungi and some yeasts (including C. neoformans).

Mycosel

cycloheximide

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________ and _______ are opportunistic pathogens. Cycloheximide will prevent their growth. Bacteria-like fungi (such as _________ ) are inhibited by chloramphenicol.

Aspergillus and Scopulariopsis

Actinomycetes

BHI- ______

Brain heart infusion

Which is more enriched

BHI or Sab-Dex?

Brain heart infusion slant (BHI) is more enriched than Sab-Dex.

BHI is used For recovery of H. capsulatum.

T/F

______ and _________ agar are used in slide cultures to induce spore formation, which aids in identification.

Potato-dextrose agar (PDA) and Corn-meal

Special media Caffeic Acid Agar - Cryptococcus neoformans will produce ______ resulting in _____ colonies (must protect media from ______). Birdseed Agar - used to _________ from contaminated cultures.

melanin ; black; light isolate Cryptococcus neoformans

Special media KT Medium & Kelley Agar - used to convert dimorphic fungus ________ from _____ to _____ form.

Blastomyces dermatitidis mycelial to yeast

Special media Modified Converse Liquid Medium (Levine's) - used to promote ______ production by _________

spherule Coccidioides immitis.

Incubation Fungal growth requirements - Temperature -____ temperature (__-__C.) for most fungi. Nocardia sp. and some dimorphic organisms grow best at ___ degrees C.

room; 25-30 37

Any fungus capable of growing at 37 C, should be considered potentially __________.

pathogenic

Incubation Atmosphere True fungi is generally _______ but there are some ______ among the _____ fungi

Aerobes Anaerobes; bacteria- like

Incubation time: Generally, cultures are held for ______

4 weeks

Some yeasts grow overnight T/F

Saprophytes are slow growers( several days) T/F

F Fast growers (several days)

Incubation time Paracoccidioides brasiliensis may require ______ weeks

4-5

Incubation time ____ weeks are recommended if Histoplasma capsulatum is suspected.

Colony Morphology Surface topography - some fungal colonies may be ____ growing, covering the _________; others may grow in a ______ manner.

free; entire surface of agar restricted

Colony morphology Surface texture - cottony or wooly (floccose), granular, chalky, velvety, powdery, suede, silky, glabrous (smooth, creamy), or waxy. T/F

Colony Morphology (continued): Pigmentation - Fungi may be colorless or brightly colored. Color may be on ______ itself, on its ______ apparatus, on the _____, or _______of the colony (reverse pigmentation).

fungus sporulating agar; on the bottom

Mycelium - Vegetative mycelium - provides _________. Aerial mycelium –_________.

nutrition reproductive

Biochemical studies - used to ID yeast and yeast- like organisms. Carbohydrate fermentation - ____________ of a carbohydrate under ———— conditions as determined by _____ and _____ production.

Growth and utilization anaerobic acid and gas

Biochemical studies - used to ID yeast and yeast- like organisms. Carbohydrate fermentation - Specimen is inoculated ________. __________ is the indicator. Acid production turns _____ to ______. Gas is detected by ____________ trapped in the fermentation tube. Observe every _______ for ———-

beneath the broth Bromcresol purple purple to yellow. appearance of bubbles 48 hours for 14 days.

Biochemical test Carbohydrate assimilation - Determines ability to ______________

utilize a carbohydrate as sole source of carbon.

Biochemical test Carbohydrate assimilation - Bromcresol purple indicator turns from _____ to ______ Tubes unchanged (as determined by __________) after _____ days are negative.

purple to yellow. comparing to a blank tube; 10

API;_________ for yeast identification

Auxocolor panels

Biochemical studies - (continued) Nitrogen assimilation - Utilizes ____ tubes with differing sources of nitrogen. ___________ is the indicator Color change of _____ to _____ is positive

3 Bromthymol blue blue to yellow

Growth on specific agars: ______________ agar - Urea is hydrolyzed by some yeast to form ammonia (pH increases) which turns media from _______ to _______ ________ medium (must protect media from ____) - Production of melanin by Cryptococcus neoformans resulting in black colonies.

Christensen's urea yellow to dark pink. Caffeic acid; light

Germ tube -_______ and ______ produce germ tubes when incubated in a protein medium.

Candidia albicans & Candidia stellatoidea

Demonstration of chlamydospores - Yeast is inoculated by jabbing appropriate agar (___________ with _______) and observed every 24 hours for 3 days for chlamydospore production.

Cornmeal with tween 80

Serology Hypersensitivity Skin tests - demonstrates _________ to a fungus. Serological tests - demonstrates __________ to a fungus; sera should be drawn in pairs (______ and _____).

T-cell immunity (cellular) B-cell immunity (humoral) acute and convalescent

Serology Hypersensitivity: ( _____ tests and _____ tests)

skin serological

Which is faster, Culture or serology

Serology is Faster compared to culture