fungus........ Flashcards
yeast reproduce by _______ (“blastoconidia”). What is the most common form of fungal infection?
yeast reproduce by budding. Candidiasis is the most common fungal infection
What is a rapid grower in germ tubes, and what is another characteristic microscopic finding for this fungus
C. albicans grows in 2-4 hrs in a germ tube.
Has large, thick, usually single terminal chlamydospores
pseudohyphae and blastoconidia suggest the genus _________. All of these spp. except for what produce pseudohyphae on a cornmeal agar
all suggest Candida spp
all Candida spp. except C. (Torulopsis) glabrata make pseudohyphae on cornmeal agar
- use RAT test to ID
Geotrichum spp. are characterized by true hyphae that segment into rectangular _____________. They look like hockey sticks
arthroconidia
C. parapsilosis colonies look like what?
spider or crossed matchstick
“logs in stream” is the colony morphology for what kind of Candida spp.?
C. kefyr
Saccharomyces spp. has characteristically roundish ______ (sexual spores in a sac) and are positive for what kind of stain?
Saccharomyces spp. has the round ascospores
pos for acid-fast stain
Cryptococcus neoformans is uncharacteristically ______ pos, while most yeast are neg. It is also _____ ____ pos due to its capsules. Where is it most commonly found in nature?
urease pos, also india ink pos
found in bird and bat droppings
C. neoformans has _____ oxidase, which can metabolize ____ ___ to melanin. What kind of agar is used for this fungus, and what color does this fungus have on this agar?
has phenol oxidase that can metabolize caffeic acid to melanin
it is red-brown pigmentation on bird-seed agar (which contains caffeic acid)
C. neoformans can cause _______, which is very common to see in AIDS patients with this fungus
meningitis
what kind of yeast is almost always associated with catheter infections?
Rhodotorula spp.
- pink on agar
what are the three zygomycetes, and what else are they called due to their colony morphology? How can you tell them apart?
Rhizopus, Mucor, and Absidia are all “lid-lifters”
Rhizopus: rhizoids on bottom of sporangiophores
Mucor: no rhizoids
Absidia: rhizoids on side of sporangiophores
- can grow up to 45 C
what diseases do the zygomycetes cause?
zygomycosis: infection of lungs, nasal sinuses, brain, eye, skin, ect
suppurative necrosis
what is the most common cause of invasive disseminated aspergilliosis? What is included with this disease?
A. fumigatus
- fungus balls in lungs
- sinusitis
- respiratory infections!
grows well at 45 C
A. niger don’t grow well at 45 C. What kind of infections does it most commonly cause?
ear infections
what kind of mycotoxins does A. flavus cause?
aflatoxins
Penecillium spp. turns ____-___ on an agar after first being white
blueish-green
common plant pathogen with canoe-shaped conidia. White with pink/purple center
fusarium spp.
what fungus has “brain” microscopic morphology? What kind of mycetoma does it cause?
Acremonium (also called “cephalosporum”) causes eumycotic white grain mycetoma
Pityriasis (tinea) versicolor is caused by what fungus and requires what for growth? What are the characteristics of this disease?
caused by Malassezia furfur and needs olive oil overlay to grow
patchy lesions or scaling of varying pigmentation of chest/abdomen/trunk
- hypopigmentation = vitiligo
Tinea nigra is caused by what fungus, and how is this disease characterized?
caused by Phaeoannelomyces (Exophiala) werneckii
characterized by hyperpigmentation
- brown to black non-scaly macules on palms and soles
white piedra is caused by?
Trichosporon beigelii
- white to light brown soft nodules around beard and moustache hairs
black piedra is caused by?
Piedraia hortae
- infection happens on scalp hair. black, hard gritty nodules
the dermatophytes can all cause _____
ringworm
microsporum spp. infects what two keratinized sources? What are the two spp. and how to tell the difference?
infect the hair and skin (but not nails)
M. canis: macroconidia with pointed ends and bumpy surface
M. gypseum: macroconidia with rounded ends and smoother surfaces (no hair projections)
what is the fungus that have “comb-like” hyphae?
Microsporum audouinii
Trichophyton spp. infects what keratinized sources?
skin, hair, and nails
T. mentagrophytes is a common cause of _____ ____. What do the microconidia look like?
athlete’s foot
grapelike clusters
(sometimes have thin macroconidia)
T. rubrum usually infects what two keratinized sources? It is the most ____ dermatophyte to infect humans
skin and nailr (usually not the hair)
most common infectious dermatophyte for humans
T. tonsurans is the principle agent of _____. They have what shaped conidia?
causes scalp ringworm
tear-drop shaped conidia on small trees/short stalks
what trichophyton causes permanent hair loss?
T. schoenleinlii
what fungus has “beaver-tail” macroconidia? What keratinized sources does it infect?
Epidermophyton floccosum infects the skin and nails only
all dermatophytes except ________? are urease pos
T. rubrum is urease neg
what three dermatophytes are hair perforation pos?
M. canis, M. gypseum, and T. mentagrophytes
fungi are seen in tissue as ____ ____ in the disease of chromoblastomycosis. What does this infection cause?
in tissue as sclerotic bodies
chronic infection of warty nodules, tumor-like masses, or raised, rough cauliflower-like lesions that have the sclerotic bodies
what do you see in a mycetoma infection?
swollen, tumor-like lesions that yield granular pus through draining sinuses
infecting agents occur in tissue as dark yeastlike cells/hyphae/pseudohyphae can cause _____________
phaeohyphomycosis
what is the most common agent of chromoblastomycosis? What are it’s four kind of conidiation?
Fonsecaea pedrosoi
- fonsecaea
- rhinocladiella
- cladosporium
- philophora
what is the second most common cause of chromoblastomycosis? What kind of micro morphology does it have?
Phialophora verrucosa: vase shaped phialides with a flared cuplike collarette
what is a common shower contaminant agent of chromoblasomycosis?
Cladosporium (“cladophialophora”) spp
- shield cells
what is the spp. that look like pumpkin seeds microscopically?
cladophialophora carrionii
what is an agent of phaeohyphomycosis that has a predilection for the brain?
Cladophialophora bantiana
what agent of phaeohyphomycosis is one of the black yeasts and is KNO3 positive?
Exophiala jeanselmei
what agent of phaeohyphomycosis has a predilection for the CNS (the brain and eye) and is KNO3 negative? What is its morphology? What test works well to grab this fungus?
Wangiella dermatitidis (exophiala dermatitidis)
conidia like a catapult on hyphae
tease prep works well
what is a main agent of mycetoma that causes black grain mycetoma?
Madurella spp.
what is called the “black killer mold” that produces several mycotoxins? Where is it commonly found?
Stachybotrys spp. is commonly found in water-damaged homes
Scedosporium prolificans causes an invasive disease characterized by what two things? It’s _________ have a swollen base and elongated necks (flask/lemon shaped)
arthritis and osteomyelitis
annellides
what kind of aerobic actinomyces is acid fast positive while all other kinds of aerobic actinomyces are AF neg? What is the most common spp. What color/texture colonies does it form? What does it smell like, and what other test is it pos for?
Nocardia (asteroides) is the most common kind of nocardia, which is AF pos. This spp. is orange and crumbly/crusty
smells like dirt and is urease pos
how to differ Streptomyces from Nocardia since they’re both gram pos bacilli/cocci
Streptomyces is acid fast neg (blue)
decomposition agars for nocardia include what three quadrants?
casein, xanthine, tyrosine
what are the six dimorphic fungi that can cause serious mycoses?
- cryptococcus neoformans
- has capsule seen in India ink stain - Blastomyces dermatitidis
- lollipop mold
- broad base yeast - sporothrix schenckii
- flower mold
- cigar bodies yeast - histoplasma capsulatum
- circular knobby mold - Paracoccidioides brasiliensis
- mariner’s wheel yeast - coccidioides spp. (eg. imminis)
- barrel-shaped arthroconidia mold
- spherules in tissue
