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173 Cards in this Set
- Front
- Back
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Describe how fungi differ from prokaryotes in terms of
reproduction size cell wall composition cytoplasmic organization |
reproduction-asexual and sexual
size- much larger, discrete nucleus cell wall composition-contains sterol cytoplasmic organization-structual units like mitochondria and endoplasmic reticulum |
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Describe the two macroscopic variations of fungi
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yeast-opaque, creamy conlonies
mold-cottony, wooly or powedery aerial growths |
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define blastoconidia
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blastoconidia-an asexual spore produced by budding from true yeasts and yeast like fungi
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define pseudohyphae
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pseudohyphae- fragile hypha-like chains of blastoconidia which elongate but fail to detach from the parent cell. They are constricted at the point of attachment but true hyphae are not
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T/F yeast can reproduce sexually
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true, two cells fuse
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Describe the incidence of yeast in clinical specimens
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the incidence of yeasts in clinical specimens in high but not always significant
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What factors have lead to the increase in the incidence of yeast infections
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steroid use, braod spectrum antibiotics, antitumor agents, AIDS
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What are the two genera of medically important yeasts
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Candida and Cryptococcus
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Are Candida normal flora?
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Yes. Candida species can be found in low numbers as indigenous flora of the mouth, throat, large intestine, and vagina
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What diseases are cause by candida species
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oral thrush, vaginitis, cutaneus infections
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T/F C. albicans can cause blood stream infections
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true
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Where can Crytococcus neoformans be found?
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lives naturally in soil containimnated with bird droppings particularly from pigeons
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What is the most common disease associated with Crytococcus neoformans infection?
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Meningitis
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Give an example of a unique cellular component of Cryptococcus neoformans that is important for identification
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large polysaccharide capsule, detected with india ink test
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What is the difference between a vegetative and aerial hyphae
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vegetative- secures the fungus to the substrate, absorb nutrients
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define conidia
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an asexual spore borne externally on the hyphae or on a conidiophore
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What are the three groups of molds we learned about
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1. opportunistic filamentous molds
2. dimorphs- systemic mycoses 3. dermatophytes- superficial and cutaneous mycoses |
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List three opportunistic molds
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Zygomycetes, Aspergillus, Alternaria
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Define saprobic
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soil loving
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Describe the growth patterns of dimorphic fungi
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most develop as yeasts when grown at 37 and molds at 25
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How is infection with a dimorphic fungi obtained
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inhlabtion of conidia (blastomycosis and histoplasmosis) or arthorconidia (coccidiomycosis)
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What is unique about the location of infections with dimorphic fungi
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infections can disseminate to internal organs of the body, bone, skin
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What organism causes Histoplasmosis?
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Histoplasma capsulatum
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What cells does histoplasma capsulatum infect
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cellls of the reticuloendothelial system= macrophage (intracellular parasite)
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How would a human aquire an infection with Histoplasma capsulatum
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Inhalation of conidia (microconidia) that are found in soil contaminated wit hbrid and bat droppings (guano)
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Where is Histoplasma capsulatum endemic
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eastern and central United States
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What organism causes Blastomycosis
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Blastomyces dermatitidis
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Where is Blastomyces dermatitidis endemic
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Misssissippi Valley region
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How is Blastomycosis obtained and what it the progression of the infection
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obtained through inhalation of conidia from moist soils, spreads and involves lungs, bone, and cutaneous tissue
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What organism causes coccidioidomycosis
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Coccidioides immitis
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Describe the disease associated with Coccidioides immitis
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generally acute, self limiting respiratory tract infection, less than 0.5% of people infected ever become seriously ill
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Where is Coccidioidomycosis endemic
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semi arid regions in southwestern US and northern Mexico
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how do humans aquire coccidioidomycosis
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inhalation of barrel shaped conidia (arthroconidia) from contaiminated soil, especially in the dry season
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Describe the association of dermatophyte infection with host tissue
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the fungi invade and digest the keratin in the skin, nails, and hair. There is no penetration into deeper tissue or invasion of the body
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Describe the sxs associated with dermatophye infection
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range from minimal to severe
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how is infection with a dermatophyte obtained
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contact with infected induviduals or animals or by contact with soil in which the dermatophyte is present
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what are two other names for dermatophyte infections
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tinea or ringworm
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What are the three genera of dermatophytes that can cause mycoses
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Microsporum, Trichophyton, Epidermophyton
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How should a direct exam of a dermatophyte infection be preformed
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Skin scraping using a KOH mount
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How can a dermatophyte be cultured
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use DM or SDA to isolate. then view the microscopic morphology of the hyaline growth with LPCB
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How can the histology of mycotic infections be observed
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use HE, PAS or Silver stains
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What is the purpose of the KOH in KOH mounts
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-breaks down extrneous debris and softens deratin
-does not damage the fungal cell wall -fungi are easily visible but unstained |
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Describe the purpose of the calcofluor white stain
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nonspecific fluorochrome dye used for direct detection of fungal elements in clinical materials. The dye binds chitin and appears apple green when exposed to UV light.
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What does calcofluor white bind
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chitin
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why is the gram stain less often used in mycology
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the cell wall of mycotic organisms, which is composed of chitin, glucan, and mannan, does not always bind the stain
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For definitive identificatino fungi must be...
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cultured and observed
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what media is most commonly used for fungal culture
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Sabouraud dextrose agar
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What medium should be used to culture clinical fungal samples from non sterile sites
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selective media containing cyclohexamine
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What is the purpose of each component of LPCB
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lactic acid- preserves the fungal structures
phenol- kills the fungi cotton blue- stains |
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What is the disadvantage of a tease mount
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manipulating the fungi may disrupt the delicate microscopic structures (relationship betweeen conidia and hyphae)
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Describe how to prepare a slide culture
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-tease hyphal elements and spore from edge of mold growth
-inoculate the top and side of the four edges of the potato flake agar block -place a sterile cover slip on top of the block -transfer 3mL sterile water into bottom of Petri dish to saturate filter paper -the fungus will grow on the sides of the agar and out on to the slide and coverslip |
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Describe how to harvest a slide culture
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-romve the coverslip from the culture
-place drop of LPCB onto clean slide -lay the coverslip onto the slide, do not press down!! -observe hyphal growth from the block edge around the square void -for permanent preps, rim the slide with clear nail polish |
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describe how a mycology slide should be viewed
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-reduced light
-10x or 40x not 100x -no oil |
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Describe how the chlamydospore production test is carried out
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-used to Dx C.albicans
-plate on cornmeal tween 80 agar -innoculate plates at 30C for 24 to 48 hours -look for pseudohyphae, cltusters of arthroconidia, blastoconidia, or think walled round chlamydosproes at the terminal end of the hyphae |
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List two morphological tests that can be used to Dx C. albicans
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-chlamydospore production on cornmeal tween 80 agar
-germ tube formation in serum |
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Describe how a germ tube test is preformed
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-colony of yeast in suspended in rabbit or human serum
-tube incubated at 37C for NO MORE THAN 3 HOURS -use wet prep to look for prescence of germ tube |
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What is a germ tube
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nonseptate extension 1/2 the width and 3-4 times the length of the yeast cell. Characteristic of C. albicans
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What is the india ink test primary used to identify
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Cryptococcus neoformans, ID pased on large polysaccharide capsule
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How does the india ink test work?
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small drop of ink is placed on glass slide then small amount of specimen is mix in
prep is viewed under 10 then 40x abscence of stain is positive for a capsule (negative staining technique) |
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draw a picture of microsporum macroconidia
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oval shpaed with tapered ends
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Draw a picture of microsporum microconidia
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few, slightly clubbed
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Draw a picture of trichophyton microconidia
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numbers, club shaped, singly or in grape like clusters
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Describe the macro and micro scopic morphology of zygomycetes
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macro- "Don King" aerial growth, fuzzy, white, hyaline
micro-"lolipops" sporgangium on |
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Describe the macro and micro scopic morphology of Aspergillus
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macro- yellow. greeenish, hyaline growth
micro-Joanne's hat, vesicle with beadead conidia |
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Describe the macro and micro scopic morphology of alternaria
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macro-black on top and bottom, dematiaceous
micro- oval shapled conidia continuous within the conidiophores |
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describe the morphology of a C. albicans chlamydospore
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thick walled, spherical swelling at the terminus of the pseudohyphae
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compare the mold forms of the dimorphic fungi
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coccidiodes- rectangular sections
blastomyces- lolipop histoplasma- spike ball |
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What type of organism would you suspect if a direct exam revealed:
-budding yeast forms only -yeast and pseudohyphae -hyphae only |
budding yeast only= yeast
yeast and pseudohyphae= Candida albicans hyphae only= filamentous mold |
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what is the full name of SDA agar?
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sabouraud dextrose agar
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Houw might the two hyaline filamentous molds be differentiated microscopically
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aspergillus- septate hyphae, branched conidia
zygomycetes- aseptate hyphae, sporangiophores with spores |
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what types of infections are usually associated with zygomycetes, a hyaline opportunistic filamentous mold
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rhinocerebral, gastric, cutaneous
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What types of infections are usually associated with aspergillus a hyaline opportunistic filamentous mold
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allergies, pulmonary, cutaneous
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Compare the growth rates of the three different type of fungi that we studied
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aspergillus or zygomycete 2-5 days
dermatophytes 7-14 days dimorphic molds- more than 14 days |
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what types of infections are associated with yeasts
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mucocutaneous, cutaneous, systemic
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list two morphological tests associated with C, albicans diagnosis
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1. germ tube test
2. clamydospores on cornmeal tween 80 agar |
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How does C. glabrata differ from C. albicans on cornmeal agar and germ tube test
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germ tube- not formed
conrmeal- no pseudo hyphae, blastoconidia only |
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What would you see on conrmeal agar for Cryptococcus neoformans
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blastoconidia only, no pseudohyphae
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describe the route of infection for a thermal dimorph
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inhalation, respiratory infection, dissemination to organs, skin, etc
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Describe the temperature dependent growth morphology of dimorphs in vitro
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@25= mold
@37= yeast except C. immitis |
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What is the diagnostic form of Histoplasma capsulatum
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mold @25, tuberculate macroconidia (spiky ball)
yeast @37 small yeast |
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What is the natural habitat of aspergillus
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ubiqutious, poants, soil
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what is the infectious form of aspergillus
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conidia
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what is the mode of transmission of aspergillus
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inhalation
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what is the clinical in vivo form of aspergilllus
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hyphae, septate and parallel
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what is the diagnostic form of aspergillus (in vitro)
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mold at 25 and 37, hyaline growth rate,
vesicle with branched conidia |
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what is the natural habitat of blastomyces dermatitidis
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WATERWAYS! soil, wood
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what is the infectious form of blastomyces
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conidia
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what is the mode of transmission of blastomyces dermatidis
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inhalation
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what is the clinical, in vivo form of blastomyces dermatidis
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yeast
BBBB! big broad based buds of blasto |
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What is the in vitro diagnostic form of blastomyces
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mold @ 25 with lolipop conidia, hyaline
yeast @ 37 with big broad based buds |
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What is the natural habitat of Candida albicans
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human flora
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What is the infectious form of C. albicans
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yeast, pseudo and true hyphae
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What is the mode of transmission of C. albicans
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contact, change in normal flora leading to dissemination
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What is the clinical, in vivo form of C. albicans
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yeast, pseudohyphae and true hyphae
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What is the diagnostic, in vitro form of C. albicans
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yeast at 25 and 37, germ tube in serum, chlamydospores on cornmeal agar
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what is the natural habitat of coccidioides immitis
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soils of aird regions
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What is the infectious form of coccidioides immitis
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arthroconidia
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What is the mode of transmission of coccidioiodes immitis
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inhlalation
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What is the clinical, in vivo form of Coccidioides immitis
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spherules with endospores
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What is the diagnostic in vitro form of Coccidioides immitis
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mold @25, arthroconidia, hyaline
NO yeast, spherules/ endospores in tissue |
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What is the natural habitat of Crytococcus neoformans
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bird feces, soil
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What is the infectious form of Crytococcus neoformans
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yeast
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What is the mode of transmission of cryotococcus neoformans
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inhalation
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What is the clinical in vivo form of cryptococcus neoformans
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yeast w/ capsule
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what is the diagnostic in vitro form of cryptococcus neoformans
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mucoid yeast colony at 25 and 37
india ink view of capsule biochems, latex agglutination for capsule |
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What is the natural habitat of Histoplasma capsulatum
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bat and bird feces
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what is the infectious form of crytococus neoformans
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yeast
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What is the mode of transmisson of histoplasma capsulatum
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inhalation
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what is the clincal in vivo form of histoplasma capsulatum
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small yeast within macrophages
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what is the in vitro diagnostic form of histoplasma capsulatum
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mold @25 with tuberculate conidia, hyaline
yeast @37, small yeast |
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What is the natural habitat of dermatophytes
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human/ animal disease and soil
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What is the infectious form of dermatophytes
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conidia, hyphae
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What is the clinical, in vivo form of dermatophyes
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hyphae w/ KOH, septate and parallel
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What is the diagnostic in vitro form of dermatophytes
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mold @ 25, 37, hyaline
micro and macro conidia shapes ` |
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What is the natural habitat of zygomycetes
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ubiquitous
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what is the infectous form of zygomycetes
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spores
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what is the mode of transmission of zygomycetes
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inhalation, ingestion, cutaneous
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what is the clincal, in vivo form of zygomycetes
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aseptate hyphae, not parallel
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what is the diagnostic, in vitro form of zygomycetes
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mold at 25 and 37, hyaline
micro morphology with sporangium and spores, lid lifter areial growth |
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What is the natural habitat of dematiaceous molds (alternaria)
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ubiquitous
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what is the infectious form of the dematiaceous molds (alternaria)
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conidia
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what is the mode of transmission of the dematiaceous molds (alternaria)
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inhalation, trauma
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what is the clinical, in vivo form of the dematiaceous molds (alternaria)
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melanin pigmented septate and parallel hyphae
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What is the in vitro diagnostic form of dematiaceous molds (alternaria)
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mold at 25 and 37, dematiaceous
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what are three ways to grow virus
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1. in lab animals
2. in embryonated eggs 3. in cell cultures |
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How might viral growth be observed in each of the three ways to culture them given that they are too small to be stained
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in lab animals- symptoms, death
in eggs- death of embryo, leisions on tissue of egg, aggultination with fluid in cell culture- cytoplathic effect |
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How do influenza type A and B differ
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different ribonucleoprotein antigens
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What is the difference between antigenic drift and antigenic shift
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drift-minor changes to surface antigens
shift-major change in surface antigen |
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What is serialy diluted in the hemagglutination assay
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virus
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what is keep constant in the hemagglutination assay
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the amount of RBCs
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What is a positive result in a HA assay
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a shield, indiactes that there were virus particles present that were able to agglutinate the RBCs
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what controls should be used in the HA assay? What do they tell you
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RBC control with no virus, ensures that cells are not spontaneously aggultinating
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what is diluted in the HAI test
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serum
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what is held constant in the HAI test
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the amount of virus
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What is a positive result in an HIA test
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A button, indiactes that there were antibodies to the virus that were able to inhibit the virus from agglutinating the RBCs
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What are the controls used in a HIA assay? What do they tell you
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cell control- RBCs alone, controls for spontaneous agglutiation
virus control- RBCs +virus, no serum, ensures that the virus can agglutinate the cells |
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What fold increase in titer is consididered significant
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4 fold increase (2 tubes)
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What are the two main antigenic glycoproteins on the influenza virus
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1. hemagglutinin- use to attach to the mucoprotein receptor of the respiratory endothelial cells, agglutinates RBCs
2. Neuraminidae- associated with relase of virus from infected cells |
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T/F HA assay quantifies viable virus
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false, the dest cannot distinguish beteween active and inactive virus particles
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What assay is required to quantify infectious virus
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cell culture
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What are the two ways to use the HIA assay
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1. use to detect viral antibody by adding unknown serum to known virus
2. use to identify an unknown virus by adding knownw specific monoclonal antiboides |
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What happens to the HI titer if more than the standard amount of virus is added
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The titer decrease because there is more virus to agglutinate so the avaiable antibody is used up faster
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What happens to the HI titer if less than the standard amount of virus is added
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The titer increases because there is less virus there for the antibody to inhibit, you can "strech" the antibody farther
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What is the principle behind BSC's
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laminar flow, the working environment is protected from dust and contamination by a constant, stable flow of filtered air passing over the work surface
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What is the pupose of HEPA filters
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-High efficiency particulate air
-filters airborne particles with 0.3um filter size |
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Describe a class II vertical laminar flow hood
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-room air is pulled into unit
-blows down onto the work surface and drawn through work surface |
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What three things does a class II BSC protect
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-personnel
-product -environment |
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How should items be placed in a hood
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clean to dirty, never place non sterile items upstream of sterile items
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define primary culture
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cells fresh from a tissue speciumen, not passaged
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describe the procedure for transfering cells
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1. remove old media
2. wash old plate x2 to remove serum 3. add trypsin EDTA and incubate at 37 for 3-10min 4. add new media with serum 5. remove appropriate amount of cells and dilute in new flask or plate |
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describe the titration of infectivity test
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used to quantify infectious virus. virus is added at ten fold dilutions to monolayer, observe cytopathic effect
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define diploid cell strain
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subculture of primary culture
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how should TC media be sterilized
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Do not autoclave, filter with gas pressue
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what type of microscopy is used to view cell lines
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phase contrast, based on different indicies of refraction
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what is the TCID 50
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the amount of virus needd to infect 50% of wells at that specific concentation. a standard amount of virus used in Viral neutralization assays
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what the purpose of using methylcellulose in viral titrations
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localized infections so each plaque is formed by one virus
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Describe the viral neutralization assay
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If antibody is present, the infectivity of the virus is neutralized and the cytopathic effect will not be observed can detect and quantify the patient antibody
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What controls should be used in the viral neutralization assay
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1. virus control to ensure that virus leads to cytopathic effect
2. normal cell control to ensure that uninfected cells are growing normally |
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what control should be used in a viral titration
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dilutent only to ensure that the cells are growing normally
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What is this
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This is the dematiaceous hyphae of Alternaria. Notice the conidium continuous withing the conidiophore. The melanin pigment excludes the LPCB stain.
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What is this?
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This is the macroconidia of microsporum canis, a dermatophyte mold
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What is this?
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This is the microconidia of trichophyton
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What is this
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This is the microscopic morphology of Zygomycetes. Notice the sporganium and spores
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What is this?
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This is the microscopic morphology of Aspergillus. Notice the vesicle with beaded conidia
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What is this?
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This is the blastoconidia/ pseduohyphae morphology of C. albicans
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What is this
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This is the chamydospore morphology of C. albicans on cornmeal tween 80 agar
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What is this
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This is the chlamydospore morphology of C. albicans on conrmeal tween 80 agar
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What is this
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This is tissue infected with Cryptococcus neoformans. Notice the "halo" around the yeast which is a result of the capsule.
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What is this?
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This is the diagnostic form of Histoplasma. Notice the tuberculate macroconidia
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What is this?
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This is the lolipop conidia of blastomyces
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What is this
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This is the yeast form of blastomyces. Notice the Big Broad Based Buds (BBBB)
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What is this?
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This is the barrel shaped arthroconidia of Coccidioides immitits
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What is this?
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This is the spherule with endospore, the in vivo form of coccidioides immitis
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