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200 Cards in this Set
- Front
- Back
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How do yeasts reproduce asexually?
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budding (usually a single bud)
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What is a yeast bud cell known as?
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blastoconidia
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Dimorphic yeasts can take up to 3 weeks to grow (T/F)
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True
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What is typical colony morphology for monomorphic yeasts?
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Dry, creamy-white to pasty white, entire
Exceptions: Cryptococcus neoformans, Rhodotorula |
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What are the physiological characteristics that may be used to identify yeasts?
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assimilation or fermentation of carbohydrates, production of urease, assimilation of nitrate, caffeic acid reaction, temperature tolerance, cycloheximide resistance
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Yeasts grow better in what atmospheric conditions?
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aerobic
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Monomorphic yeasts exist in one form regardless of _______
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temperature
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Cadidiasis may occur in what location in the body?
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Almost anywhere - mouth, pharynx, vagina, skin, nails, intestine, bronchopulmonary, perianal, blood, etc.
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Candida kefyr is most often associated with that type of infection?
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nail infection
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Candida krusei is a colonizer most often associated with what patients?
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those undergoing therapy with fluconazole
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Candida lucitaniae is associated with _________ disease and is resistant to _________
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systemic, Amphoteracin B
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Amphoteracin B has what negative side effect?
Is this the drug of first choice for candidiasis? |
toxicity to renal system,
no longer drug of first choice due to toxicity |
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Candida arapsilosis causes what infections?
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endocarditis, fungemia, onchomycosis
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Candida tropicalis is a major pathogen in _______ patients and causes ____________ infections.
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immunocompromised, disseminated
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Candida glabrata causes
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opportunistic infections, usually involving the kidneys or lungs
Can cause fungemia and septic shock |
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Candida exists as normal flora in...
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the oral cavity, genital area and gastrointestinal tract
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Some predisposing factors to yeast infections are...
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diabetes, pregnancy, antibiotics, burns, invasive procedures, immunosuppression
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Candida specimens must be freshly collected due to...
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the normal resident nature of Candida and the rapid multiplication of organism
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What number of yeast organisms are considered significant in urine?
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10,000/milliliter
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What antibiotics are added to SDA when testing non-sterile areas of the body for yeast?
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penicillin, streptomycin and chloramphenicol
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Cyclohexamide
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antifungal that inhibits yeasts that might overwhelm the plate
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What color is Candida albicans on CHROMagar?
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green
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What automated tests are used to determine yeast species?
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biochemical carbohydrate fermentation/assimilation tests
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What serological tests may be used to diagnose candidiasis?
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latex agglutination, CIE, immunodiffusion
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Candida glabrata is primarily seen in ________ patients and mostly causes ________ disease. This infection is often _______ in origin.
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debilitated (especially AIDS), systemic, nosocomial
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Candida glabrata may be normal flora (T/F)
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True
Found in oral, GI and urinary tracts |
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How does Cryptococcal infection usually begin?
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With a respiratory tract infection
May later involve brain and meninges |
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How can Cryptococcus be detected on direct microscopic examination?
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india ink or nigrosin to detect capsule
calcoflour white |
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Cryptococcus is ______ to cyclohexamide
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sensitive
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On what medium is Cryptococcus neoformans usually grown? What do the colonies look like on this agar?
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Birdseed/nigerseed/caffeic acid agar. The colonies are a brown to black color, with a very mucoid appearance.
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What color is Cryptococcus neoformans on birdseed agar?
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brown to black
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What length of time is required for growth of Cryptococcus? What temperature is desired?
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48-72 hours, 37 degrees (will have wrinkled colonies at lower temperatures)
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How do colonies of Rhodotorula normally appear?
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moist with orange pigment
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What sugar does Rhodotorula NOT assimilate?
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inositol (C. neoformans does assimilate this sugar)
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Trichosporon usually affects ______ patients, especially those with ______.
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immunosuppressed, leukemia
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Geotricum species have blastoconidia (T/F)
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False, Geotrichum does not produce blastoconidia
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What is the most common type of disease caused by Geotrichum?
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Respiratory infection, although this organism rarely causes disease.
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What do arthroconidia of Geotrichum look like under the microscope?
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They have even staining with square ends
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What are the two types of hyphae that molds can form?
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aerial and vegetative
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Aerial hyphae
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support reproductive structures, give colony color
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Vegetative hyphae
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spread easily, root growth that supports colony
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In what position are mold plates inoculated and incubated?
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inoculated in the middle and incubated top side up
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At what temperature do molds grow best?
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30 degrees celsius
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Septate hyphae
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have cross walls, usually narrower than aseptate hyphae
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Aseptate hyphae
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do no have cross walls, usually wider than septate hyphae
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Mycelium
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group of hyphae
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Molds are identified primarily on....
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morphological characteristics, colony characteristics
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Aspergillus infections are ____ and primarily begin in the _____
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opportunistic, respiratory tract
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Disease states associated with Aspergillus
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Allergy, secondary colonization, systemic
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Aspergillus colonies grow in _____ days and appear ______ in color and ______ in texture
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2-6, white at first then varied depending on species, granular to cottony
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Color of Aspergillus flavus
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yellow to green
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Color of Apergillus terreus
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tan
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Color of Aspergillus fumigatus
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gray to gray-green
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Color of Aspergillus niger
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black
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Aspergillus has septate/nonseptate hyphae
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septate
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Phialoconidia
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chain of spores that arise from the phialids of the vesicle
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Penicillium marneffei
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emerging disease affecting AIDS patients in southeast Asia, dimorphic (yeast in tissue, mold at rt), red color
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Penicillium have conidiophores with vesicles (T/F)
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False
Penicillium species do have conidiophores but they lack vesicles |
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Color of Paecillomyces colony
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gold to lilac (NEVER blue-green)
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Phialaconidia bend away from phialids in this organism
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Paecillomyces
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Scopulariopsis is found in the environment in...
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soil and decaying vegetation
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Scopulariopsis causes...
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onchomycosis usually
occasionally pneumonia, fungus ball, otitis media |
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Scopulariopsis colonies appear...
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white then tan to light brown, powdery, have irregular folds in colony center
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Fusarium is found in the environment in...
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soil, rotting vegetation and fruit
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Fusarium colonies usually appear...
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white then pink to violet, velvet-like then cottony texture
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Zygomycetes are characterized by...
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aseptate hyphae terminating in sporangia
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Zygomycosis is prevalent in patients with....
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uncontrolled diabetes, other types of immunocompromised patients
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Zygomycosis usually infects...
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nasal passages, orbital areas, then may spread to brain and meninges
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Zygomycetes fill a plate with _____ in _____ hours.
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loose, aerial hyphae, 24 to 48 hours
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Classification of zygomycetes is based on the presence or absence of....
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rhizoids
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Rhizopus colonies appear...
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white becoming gray to black, "salt and pepper"
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Rhizoids are found _____ in Rhizopus
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at the base of the sporangiophore
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Mucor has rhizoids (T/F)
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False, rhizoids are absent in Mucor
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Syncephalastrum has this type of appearance microscopically
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"daisy-like" due to the extension of sporangia outside of the sporangium
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Why is a microscopic tease preparation necessary for LCB visualization?
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In order to see individual structures of molds under the microscope
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Why are slide cultures necessary?
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To examine the relationship of spores to the hyphal structures
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What type of conidia does Scopulariopsis produce?
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anneloconidia
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What do the phialoconidia of Aspergillus look like?
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Hands
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What do the phialoconidia of Penicillium look like?
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Brushes
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Dematiaceous means...
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soil-loving
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Dematiaceous opportunists produce _____ hyphae and colonies
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dark (black-grey to black)
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Alternaria is found ______
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world-wide, usually in the soil
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Alternaria may cause ________
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phaeophyphomycosis, sinusitis, asthma, osteomyelitis, otitis, and conjuctivitis
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Alternaria hyphae appear ______
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septate and darkly pigmented
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Alternaria conidiophores appear _____
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septate and darkly pigmented
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Poroconidia of Alternaria appear _______
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septate (longitudinal and latitudinal cross-walls), in chain-like formations
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Bipolaris poroconidia appear...
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oblong with several cells inside and darkly colored (pea-pod appearance)
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Curvularia is commonly found...
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in air and soil
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Diseases caused by Curvularia
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endocarditis, onychomycosis, mycotic keratitis, sinusitis, pulmonary and nasal infections, phaeophyphomycosis
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Colonies of Culvaria appear _____ and culture in _____
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black and cottony, 5-6 days
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Poroconidia of Culvaria have _____ cross-walls
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latitudinal (transverse) only
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Phaeohyphomycosis
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subcutaneous and systemic infections cause by the dark-walled hyphae in tissue
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Dematiacious organisms should be cultured on ______
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SAB with cyclohexamide and without cyclohexamide
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Subcutaneous phaeohyphomycosis produces _____ lesions that occur at the site of ________
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cyst-like, traumatic implantation
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Phialophora annelloconidia look like ____
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vases with flowers
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Specimens of choice for subcutaneous mycoses
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hair (plucked from roots, usually broken and scaly hair), skin (cleansed first with alcohol to remove surface bacteria)
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Malassezia furfur causes....
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pityriasis versicolor (also called liver spots) which causes scaly patches of different colors on chest and back which fluoresce under a Wood's lamp
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KOH preparations of Malassezia furfur appear...
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like spaghetti and meatballs (cells in clusters surronded by septate hyphae)
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Malassezia furfur must have an overlay of _______ to grow in agar
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olive oil
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Exophilia werneckii causes....
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tinea nigra (brown to black scaly patches on palms of hands)
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Exophilia werneckii is treated with....
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topical azoles
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Black piedra affects ______
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the hair of the scalp
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White piedra affects ______
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the hair of beard and moustaches
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Trichosporon produces both ______ and _______ conidia
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arthro- and blasto-
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Chromoblastomycosis
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Subcutaneous infection involving primarily the lower extremities as a result of trauma or puncture wounds, characteristic cauliflower-like subcutaneous nodules and microscopic sclerotic bodies
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Sporotrichosis is
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A chronic infection characterized by nodular lesions and ulcers in the lymph nodes, most often associated with roses though any contaminated sharp woody instrument may transmit disease, world-wide distribution
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Sporothrix schenckii has what type of microscopic morphology?
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Dimorphic - cigar-shaped yeasts (37 degrees) and branching hyphae with tear-drop conidia in form of flowerette arrangement (30 degrees)
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Sporothrix schenckii has what type of colony morphology?
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30 degrees: White at first, wrinkled, become black and develop short aerial hyphae
37 degrees: moist, yeast-like (entire) |
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The yeast form of Sporothrix schenckii may be confirmed using....
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IFA or calcafluor white
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Dimorphic fungi may be normal flora (T/F)
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False, dimorphic fungi are NEVER normal flora
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Direct wet mounts are useful for dimorphic fungi because ______
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the length of time for growth in vitro is so long and because direct examination is often diagnostic
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Histoplasmosis may be observed inside _______ on Wright stain because the organism prefers the _____
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WBCs, reticuloendothelial system
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Histoplasma, Blastomyces, Coccidioides and Paracoccoides cause..
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pneumonia, skin manifestations and systemic disease
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Histoplasma capsulatum is associated with these animals
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bats, starlings and chickens (esp chicken houses)
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According to skin test, 95% of Histoplasma infections are...
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benign
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Clinical disease of Histoplasma capsulatum
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pneumonia (add more later)
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Diagnostic form for histoplasmosis
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Tuburculated macroconidium or tuberculated chlamydoconidium of the mold form grown in vitro at room temperature
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Blastomyces dermatitidis causes...
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a chronic granulomatous disease that may be pulmonary, cutaneous or systemic, mimics tuberculosis
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Direct examination of Blastomyces dermatitidis may reveal....
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a large, broad-based attachment of mother cell to bud in the yeast form
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Paracoccidiomycosis basiliensis causes...
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a disease similar to blastomycosis that occurs mostly in South America, mostly affects the pulmonary system
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Paracoccidioides brasiliensis appears ______ in the diagnostic ____ stage
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as a large, thick-walled cell with multiple buds (mariner's wheel), yeast
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Coccidioides immitis causes...
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a pulmonary and disseminated infection, rarely cutaneous, systemic disease may be fatal
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Infection with Coccidioides immitis is known as...
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San Joachim valley fever
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The mold colony of Coccidioides immitis appears...
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white with loose, aerial hyphae
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The two diagnostic forms of Coccidioides immitis
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Spherules with endospores, arthroconidia with alternating staining
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Dermatophytes are limited to the ________ because they require ________
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hair, skin and nails, keratin
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Three genera of dermatophytes
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Microscporum, Trichophyton, Epidermophyton
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Sources of infection for dermatophytes
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animals, humans, soil
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Tinea corporis
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body dermatophyte infection
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Tinea capitis
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head dermatophyte infection
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Tinea pedis
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foot dermatophyte infection
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Dermatophyte infection is commonly known as...
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ringworm
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Dermatophyte specimens should be refrigerated (T/F)
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False, they should NOT be refrigerated because E. floccosum is sensitive to cold temperatures
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Areas infected by Microsporum
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hair and skin
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Areas infected by Trichophyton
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all keratin containing tissue (skin, hair, nails)
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Areas affected by Epidermophyton
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skin and nails
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Sporulation of Trichophyton
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microconidia, and smooth-walled, pencil-shaped macroconidia
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Sporulation of Epidermophyton
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smooth macroconidia only that appear in bunches
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Sporulation of Microsporum
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Macroconidium that is cigar-shaped with irregular edges, multicelled, microconidia
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Rice grain test
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Microsporum audouini will not grow
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Wood's lamp fluorescence
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Microsporum infected hairs (M. audouini)
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Trichophyton mentagrophytes is urease _____ and T. rubrum is urease _____
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positive, negative
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Microsporum usually causes...
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tinea capitis or tinea corporis
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Microsporum invades hair in an _____ manner
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ectothrix
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Microscporum audouinii is transmitted ______
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from human to human
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Microsporum canis
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Ringworm of dogs and cats, zoonotic, yellow-orange-red of reverse of agar, pointed, echinulated, multi-septate macroconidia
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Microsporum gypseum
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geophilic, rapid growth, buff-granular colony, round-tip echinulated macroconidia
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Microsporum nanum
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Zoonotic from pigs, one to two celled echinulate macroconidia
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Microsporum cookei
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soil fungus, usually nonpathogenic, multiseptate echinulate macroconidia, may have teardrop microconidia, orange to red reverse, fluffy white surface
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Trichophyton mentagrophytes causes....
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tinea pedis
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Trichophyton mentagrophytes invades the hair in an _______ manner
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ectothrix
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Trichophyton mentagrophytes will/will not perforate hair in vitro
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will
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Trichophyton rubrum frequently causes....
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tinea corporis and tinea pedis
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Trichophyton tonsurans commonly causes....
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tinea capitis
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Trichophyton schoenleinii causes....
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favus, a severe scalp infection
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Epidermophyton floccosum causes...
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jock itch
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E. floccosum produces both macroconidia and microconidia (T/F)
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False, epidermophyton produces only macroconidia
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What are the two basic categories of fungi?
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yeasts - small, oval/round forms that reproduce by budding
molds - large, filamentous forms that reproduce by a variety of means |
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Yeasts grow well at what temperature?
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Both room temperature (30) and body temperature (35-37)
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Two genera of yeasts that are of major medical importance
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Candida, Cryptococcus
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Candida colonies can be observed 24 hours after plate inoculation (T/F)
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True, Candida colonies appear as early as 24 hours and as late as 72 hours after plating
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Candida colonies appear ______ on SBA, chocolate agar, potato dextrose agar and corn meal agar
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white to off-white, opaque and entire
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All yeasts and yeast-like fungi are Gram ______
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positive
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Which Candida species does NOT produce pseudohyphae?
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Candida glabrata
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Lactophenol cotton blue stains what cellular component?
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chitin
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What is a germ tube?
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A hyphal extension produced by Candida albicans when incubated at 35 degrees celsius with rabbit serum
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Candida albicans colonies appear what color on CHROMagar?
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light to medium green
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Candida tropicalis colonies appear what color on CHROMagar?
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dark blue
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Candida krusei colonies appear what color on CHROMagar?
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light mauve with a white border
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Cryptococcus neoformans has the ability to cross the spinal fluid barrier (T/F)
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True, this species possesses a large capsule that allows it to cause meningitis
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India ink is used to demonstrate what cellular structure?
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capsule
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Cryptococcus neoformans colonies appear ______ on non-differential media
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opaque, white to off-white, entire and moist
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Cryptococcus neoformans colonies appear ________ on birdseed agar
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brown to black
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Monomorphic yeasts usually grow on artificial media in 24-72 hours (T/F)
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True
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What are the microscopic morphological characteristics that may be used to identify yeasts?
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Capsules, pseudohyphae, hyphae, germ tubes, chlamydoconidia, ascospores, basidiospores
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Monomorphic yeasts produce blastoconidia only at 37 degrees (T/F)
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False, monomorphic yeasts produce blastoconidia at both 30 and 37 degrees
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Most candidiasis is caused by what species?
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C. albicans
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Sources of Candida infection
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Animals/Birds
dogs, cattle, pigs, lambs, horses, rodents, guinea pigs, turkeys, ducks, geese, pigeons, pheasants, quail |
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Candida species that are sensitive to cycloheximide
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C. krusei, C. tropicalis, C. parapsilosis
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C. tropicalis in the urine usually indicates....
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a systemic infection
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Which Candida species produces a germ tube?
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C. albicans
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Candida glabrata produces psuedohyphae (T/F)
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False, this species does not produce pseudohyphae
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Candida glabrata is often resistant to _______.
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fluconazole
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Biochemically, C. glabrata assimilates the sugars ____ and ____, with a negative reaction for all others
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glucose, trehalose
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What is the primary source for Cryptococcus neoformans?
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soil and soil products
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Latex agglutination may be used as a direct specimen test to detect Cryptococcus neoformations (T/F)
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True, latex agglutination has a 92% sensitivity and may be used directly on a patient sample
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What tests are used to determine the species of Cryptococcus?
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birdseed agar, carbohydrate assimilation, urease production, DNA probe, rapid nitrate production
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What do Rhodotorula and Cryptococcus have in common?
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capsule
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Rhodotorula is normally found in patients undergoing ______. It may also cause _______ in patients undergoing chemotherapy.
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peritoneal dialysis, fungemia and endocarditis.
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Trichosporon does not produce blastoconidia (T/F)
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False, Trichosporon forms blastoconidia at the corners of the arthroconidia
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Geotrichum is usually considered a suspect pathogen only after repeated isolations (T/F)
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True, Geotrichum is rarely a cause of disease so repeated isolations are necessary to rule out contamination
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How do Geotrichum colonies appear on SDA?
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initially resemble yeast but become fuzzy after continued incubation
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With the exception of Sporothrix, the primary site of initial exposure for dimorphic fungi is...
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the lung
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Dimorphic fungi generally require _______ to develop into a mature culture at room temperature
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3 to 6 weeks
The exception is Coccidiodes which requires only one week |
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What is the preferred media for incubating dimorphic fungi at 37 degrees?
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Brain heart infusion agar with blood
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What is the preferred media for incubating dimorphic fungi at 30 degrees?
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SDA or SABHI (SDA/BHI combination) agar with antimicrobials
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Direct wet mounts are usually diagnostic for dimorphic fungi (T/F)
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True, direct wet mounts are usually diagnostic for these organisms and are especially helpful due to the length of time for growth of dimorphic fungi
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What is the purpose of adding KOH to a wet mount?
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To dissolve the keratin and cellular debris of the patient tissue to make the organism more visible under the microscope
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In addition to direct wet mounts, dimorphic fungi may also be observed in ________
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blood smears with Wright stain and tissue specimens stained with H&E
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Endemic area for Histoplasma capsulatum
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Kentucky, West Virginia, Tennessee, Mississippi Valley
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