LABORATORY METHODS IN MEDICAL MYCOLOGY Flashcards by Luis Manuel Ramos

Hair & nails specimens are sent in a ____ ____.

dry envelope

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What is the appropriate processing of skin, nails, and hair for fungus isolation?

Direct exam following KOH preparation

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What is the appropriate processing of CSF for fungus isolation?

Centrifuged; examine sediment microscopically, inoculate media

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What is the appropriate processing of pleural fluid, sputum, and bronchial aspiration for fungus isolation?

Specimen must be fresh as saprophytes would overgrow pathogens such as H. capsulatum. Specimens may be refrigerated up to 2 hours.

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What is the appropriate processing of Gastric washings for fungus isolation?

Same as for pleural fluids

Specimen must be fresh as saprophytes would overgrow pathogens such as H. capsulatum. Specimens may be refrigerated up to 2 hours.

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Genito-urinary specimens are preferably collected in what timeline?

First morning

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What is the appropriate processing of blood/bone marrow for fungus isolation?

Generally inoculated directly to BHI broth and BHI slant

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What is the appropriate processing of wound abscess or drainage for fungus isolation?

Should be cultured anaerobically, especially if actinomycosis is suspected

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What is the appropriate processing of tissue speciments for fungus isolation?

Examine for pus, caseous material or granules; mince aseptically, can use small amount of sterile saline and the supernatant inoculated

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This type of direct examination method is good or yeast; examination is done in natural environment, so loss of fragile structure is minimized.

Wet mount prep

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This type of direct examination is done on skin scrapings, hail, nails, sputum, vaginal specimens, etc. The ____ clears the specimen’s tissue cells, mucous, etc., so fungal elements can be seen.

KOH prep

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This stain is very popular for quick evaluation of fungal structures; will stain the chitin in cell walls of fungi.

Lactophenol Cotton Blue (LPCB)

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This stain dyes certain polysaccharide in the cell walls of fungi. Fungi stain pink-red with blue nuclei.

Periodic Acid - Schiff Stain (PAS)

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This stain outlines fungi in black due to the silver precipitating on the fungi cell wall. Internal structures are deep rose to black; background is light green.

Gomori Methenamine Silver Stain

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This stain dyes the hyphae and yeast dark blue or rose. Tissues stain deep blue and background is yellow.

Gridley stain

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This stain will dye the capsules of Cryptococcus neoformans deep rose.

Mayer Mucicarmine stain

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This stain is simple, sensitive, and specific. Applications for many different fungal organisms.

Fluorescent Antibody Stain

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This stain is good for initial differentiation of dimorphic fungi. Works well on sputum smears.

Papanicolaou Stain

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Most fungi are gram ____; ____ and ____ are gram varibale.

positive; Actinomyces and Nocardia

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This stain differentiates acid-fast Nocardia from other aerobic Actinomyces.

Modified Acid-fast Stain

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This stain demonstrates the capsule of Cryptococcus neoformans in CSF specimens.

India Ink

In fungal culturing, tubed media is used rather than plated media because ?

there is less chance for spore release into the environment
less chance for dehydration
ease of storage

Incubation should be aerobic if Actinomycetes are suspected. True or False?

False, anaerobic

Most fungi requires anaerobic incubation. True or False?

False, aerobic

What temperature should dimorphic fungi be suspected?

37 C

Most fungal cultures are kept for ____ weeks.

Systemic fungal pathogens often require ___ days to ___ weeks for culturing.

10 days to 2 weeks

It is the classic medium for fungal isolation and it is recommended for most studies.

Sabouraud's dextrose agar (Sab-Dex)

In fungal isolation, ____ is added to inhibit bacterial growth.

Chloramphenicol

This medium is commercially available and contains **chloramphenicol** to inhibit bacterial growth; **cycloheximide** to inhibit saprophytic fungi and some yeasts (including C. neoformans).

Mycosel agar

This medium is more enriched than Sab-Dex agar and is used to recover H. capsulatum.

Brain heart infusion slant (BHI)

This medium is used in slide cultures; these induce spore formation, which greatly aids in identification

Potato-dextrose agar (PDA) and Corn-meal agar

Within this medium, Cryptococcus neoformans will produce melanin resulting in black colonies (protect media from light during incubation).

Caffeic Acid Agar

This medium is used to isolate Cryptococcus neoformans from contaminated cultures.

Birdseed agar

This medium is used to convert dimorphic fungus Blastomyces dermatitidis from mycelial to yeast form.

KT Medium & Kelley Agar

This medium is used to promote spherule production by Coccidioides immitis,

Modified Converse Liquid Medium (Levine's)

With this medium, urea is hydrolyzed by some yeast to form ammonia. The pH increases turning the media from yellow to dark pink .

Christensen's urea agar

Glabrous means ?

smooth and/or creamy

Floccose means ?

Cottony or wooly

Reverse pigmentation happens when ?

Pigmentation resides on the bottom of the colony

The top pigment produced by fungi is called ?

Obverse

Type of microscopic evaluation where the part of the colony is removed to a slide with inoculating needle. **Lactophenol cotton blue stain** often used.

Teased preparations

This type of microscopic evaluation provides a view of undisturbed microscopic morphology.

Slide Culture techniques

This type of microscopic evaluation utilized clear cellophane tape to life parts of a colony to a microscope slide.

Transparent Tape Preparation

Give the biochemical study used to ID yeast and yeast-like organisms with the given data: * Measures utilization of a carbohydrate under anaerobic conditions as determined by **acid and gas production**. * Specimen is inoculated **beneath** broth. * **Bromcresol purple** is the indicator. Acid production turns purple broth to yellow. Gas is detected by appearance of bubbles trapped in a fermentation tube. Observe every 48 hours for 14 days.

Carbohydrate assimilation & fermentation

Give the biochemical study used to ID yeast and yeast-like organisms with the given data: * Utilizes 3 tubes with different sources of nitrogen. **Bromothymol** blue is the indicator (blue to yellow is positive).

Nitrogen assimilation

Candidia albicans & Candidia stellatoidea produce germ tubes when incubated in a _____ medium.

protein

Give the procedures on how to demonstrate chlamydospores.

* Yeast is inoculated by jabbing the appropriate agar (Cornmeal agar with tween 80). * Cultures are observed every 24 hours for 3 days looking for chlamydospore production

Skin tests demonstrate what immunity against a fungus?

T-cell immunity

Serological tests demonstrate what immunity to a fungus?

B-cell immunity

Enumerate some of the serological tests used in mycology.

* Complement fixation * Agglutination tests * Precipitin tests * Immunofluorescence * Immunodiffusion techniques * Counterimmunoelectrophoresis