MLSCI340 Mycology Flashcards by Tatjana Obias

Fungal organism associated with meningitis

Cryptococcus neoformans

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Stain used in mycology that requires a fluorescent microscope

Calcofluor

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Group of organisms commonly isolated from hair, skin, and nail specimens

Dermatophytes

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Fungi showing two different morphologies

Dimorphic

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Stain that binds to carbohydrates in the fungal cell wall staining them magenta

PAS; periodic acid schiff

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Term for ringworm infecting the body

Tinea corporis

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Viewed through reverse side of the colony to help identification

Topography

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Previously classified as a protozoan and was associated with PCP

Pneumocystis jirovecii

PCP - pneumocystis pneumoniae in immunocompromised patients

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Which specimen is required for diagnosis of disseminated fungal infections ?

Blood culture

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General purpose isolation media

Sabouraud dextrose

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Silver stain used to demonstrate fungi

Grocott Methenamine Silver

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Stain used to demonstrate large capsule of Cryptococcus neoformans in CSF

India Ink

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Selective differential media for yeast

Candida Chromagar

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Dimorphic organism associated with guano

Histoplasma capsulatum

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What is used for direct examination with hair, skin, and nail specimens ?

10% KOH

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Commonly added antimicrobial that can inhibit some fungal pathogens

Cycloheximide

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Level III pathogen found in the desert

Coccidioides immitis

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Most common fungal organism isolated from urine specimens

Yeast

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Submission container for hair, skin, and nails

Envelope

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SDA: use and ingredients

Sabouraud Dextrose Agar:
- ENRICHED
- recovery of fungi
- sabouraud dextrose + BHI agar

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SDA w/ antimicrobials: use and ingredients

Sabouraud Dextrose Agar:
- SELECTIVE and ENRICHED
- inhibits certain fungi
- sabouraud dextrose + BHI agar + antimicrobials

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BHI: use and ingredients

Brain Heart Infusion:
- ENRICHED
- recovery of saprobes (bacteria or fungi)
- BHI, enzymatic digest, casein, dextrose, NaCl

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BHI w/ antimicrobials: use and ingredients

Brain Heart Infusion:
- SELECTIVE and ENRICHED
- recovery of fungi
- BHI, enzymatic digest, casein, dextrose, NaCl, antibiotics

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Mycosel: use and ingredients

SELECTIVE
recovery of dermatophytes
inhibits bacteria/ other fungi
CYCLOHEXIMIDE, chloramphenicol, dextrose

PHY/ PYA: use and ingredients

PHYTONE YEAST EXTRACT AGAR: - SELECTIVE - recovery of yeast from contaminated specimens - yeast extract, K2PO4, chloramphenicol

Source, Mode of Transmission, Infection: Candida sp

human flora contact respiratory, skin, GI

Source, Mode of Transmission, Infection: Cryptococcus neoformans

birds, feces, soil inhalation lungs, skin, meningitis

Source, Mode of Transmission, Infection: Malassezia furfur

human flora contact skin

Source, Mode of Transmission, Infection: Dermatophytes

humans, animals, soil contact skin, hair, nails

Source, Mode of Transmission, Infection: Aspergillus sp.

ubiquitous, plants inhalation lungs, eyes, skin, nails

Source, Mode of Transmission, Infection: Penicillium sp.

ubiquitous inhalation skin, respiratory, sinusitis

Source, Mode of Transmission, Infection: Pneumocystis jirovecii

humans inhalation pneumocystis pneumonia (PCP) in immunocompromised patients

Source, Mode of Transmission, Infection: Blastomyces dermatitidis

soil inhalation lungs, skin, long bones

Source, Mode of Transmission, Infection: Coccidioides immitis

soil from arid regions inhalation respiratory, meningitis

Source, Mode of Transmission, Infection: Histoplasma capsulatum

bat/bird feces inhalation guano: respiratory, bone marrow, blood,

Fungi vs bacteria: incubation period

Fungi: 4 wks Bacteria: 3 days

Fungi vs bacteria: temperature

Fungi: 22°C, 30°C, 37°C Bacteria: 37°C

Fungi vs bacteria: atmosphere

Fungi: O2 only Bacteria: O2, CO2, *

Fungi vs bacteria: agar depth

Fungi: thicker (>6mm) Bacteria: 2-4mm

Fungi vs bacteria: method of inoculation

Fungi: single touch away from edge of plate Bacteria: 4-quadrant streak

How does GMS stain fungi ?

Grocott Methenamine Silver: - black and silver outline - cyan background

why is 10% KOH added to hair, skin and nail specimens ?

breaks down keratin and skin layers to visualize fungi better

what can be added to KOH stain specimens to help with ID ?

calcofluor white

when is lactophenol cotton blue used ?

- with tape/ tease mounts - with KOH = fungi stains blue

how does calcofluor work ?

binds to cellulose of fungi cell wall = fluoresce mint green

what is india ink/ nigrosin stain used for ?

examine CSF for Cryptococcus neoformans

what type of stain is india ink/ nigrosin ?

negative stain= capsule is visualized as a clearing

Organisms associated with yeast infections

- Candida sp - Cryptococcus neoformans - Malassezia furfur

Organisms associated with superficial mycoses

- Trichophyton sp* - Microsporum sp* - Epidermophyton sp* - Malassezia furfur - Candida sp *needs keratin

Organisms associated with opportunistic mycoses

- Aspergillus sp - Cryptococcus neoformans - Penicillium sp - Candida sp - Pneumocystis jirovecii

Organisms associated with systemic mycoses

- Coccidioides immitis - Histoplasma capsulatum - Blastomyces dermatitidis

Systemic mycoses are considered level __ organisms

Systemic mycoses are considered level THREE organisms

How is topography observed in fungi ?

since aerial hyphae interferes with topography, observe reverse side of plate

Define topography

designs of hills and valleys seen on fungal cultures

what is rugose topography ?

- irregular furrows radiating from center of culture NOTE: looks like a steam bun !

what is umbonate topography ?

button-like elevation in the center of plate with possible rugose

what is verrucose topography ?

wrinkled, convoluted surface NOTE: think varicose veins !