Exam 1 Flashcards
Are fungi classified as eukaryotic or prokaryotic?
eukaryotic
What is the structural element that comprises a fungus?
hyphae
Which class of fungi has a non-septate mycelium?
Zygomycetes/phycomycetes
Why are certain fungi classified as “Fungi Imperfecti”?
lack sexual phase, or their sexual phase is unknown
How does the function of reproductive mycelia differ from that of vegetative mycelia?
vegetative mycelium grow below the surface of the medium and anchor the fungus secretes enzymes making them able to absorb nutrients; reproductive mycelium project above the surface of the medium, this is where spores are located
To which class do most pathogenic fungi belong?
Deutermycetes
What term best describes the nutritional characteristics of fungi?
saprophytic/saprotrophic
Are fungi aerobic or anaerobic?
aerobic
What is the best single medium for the primary isolation of fungi?
Sabouraud’s dextrose agar (SBA/Sabs)
What is the purpose of corn meal agar?
nutritionally deprives the organisms so that sporulation will occur
How long should routine fungal cultures be held before being discarded?
minimum of four weeks
What three things does the mounting medium lactophenol cotton blue do?
preserves fungal structures, reduce contamination of the environment, and stains the hyaline fungal structures
When a systemic mycosis has spread to various organs, what term is used to describe it?
disseminated
What organism is best described as a thick-walled yeast cell with buds attached by a broad base?
Blastomyces
Which systemic fungus is always a yeast?
Cryptococcus
How is histoplasmosis acquired?
inhalation of spores from a free-living fungus
Name the five species of dimorphic (diphasic) fungi
Blastomyces, Histoplasma, Coccidiodes, Paracoccidiodes, Sporothrix
Which systemic fungus produces thick-walled yeast cells with multiple buds in tissue?
Paracoccidiodes
Which fungus can be observed as a non-budding, thick-walled spherule containing endospores in a direct smear from the body?
Coccidiodes
Which fungus produces spiny, tuberculate macroconidia when cultured, but in the body can be seen as intracellular, yeast-like cells with a large vacuole in the cells of the RE system?
Histoplasma
Cryptococcosis is usually seen as a disease of which body system?
pulmonary
Which systemic fungus is the most fastidious in the laboratory?
Histoplasma
What systemic fungus causes San Jacquain Valley Fever?
Coccidiodes
Which systemic fungus causes South American blastomycoses?
Paracoccidiodes
Which stain is best to use to demonstrate Cryptococcus neoformans in CSF?
India ink
Which systemic fungus is endemic in Piedmont, NC and can produce a primary pulmonary infection or a primary skin infection which resembles ringworm?
Blastomyces
Which systemic fungus produces chains of arthrospores and can be confused with the saprophytic fungus Geotrichum candidum?
Coccidiodes
What is the macroscopic appearance of Sporothrix scheneckii at 37C?
Creamy, yeast colony
List several species of dematiaceous fungi?
Cladosporium, Phialophora, Fonsecaea
Which subcutaneous infection produces yeast-like brown cells in clusters in the body?
Chromomycoses; divides in all four planes; brown, sclerotic bodies
What is the most common cause of maduromycosis?
Petriellidium boydii
What color are the granules that are frequently found in the pus?
yellow to whitish granules
What fungus produces tear-shaped condo arranged in rosettes at 25C and yeast cells when grown at 37C and causes a disease common among gardeners which is referred to as “rose fever”?
Sporothrix schenkii
Name several species that can be responsible for chromomycosis.
Phialophora, Fonsecaea, Chlamydosporium
Which organisms can cause mycetomas?
Actinomyces, Madurella, Petriellidieum
An organism which produces brown, branching septet hyphae would be classified as what type of fungus?
Dematiaceous
What are dermatophytes?
organism that only invades keratinized areas (hair, skin, and nails)
What device can be used as an aid to select hairs infected with ringworm?
Fluorescent light
What type of hair infection is characterized by empty areas or tunnels where the hyphae have degenerated visible throughout the entire length of the hair?
Favic
What combination of fungal media would be best to use to culture dermatophytes?
Sabouraud’s and mycosel
Which three genera of fungi all cause ringworm of the skin?
Microsporum, Trichophyton, Epidermophyton