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106 Cards in this Set

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Define where in the body the superficial mycoses are found
Occur in outer dead layers of skin and hair
- do not penetrate living tissue
Explain why a patient would seek medical attention for a superficial mycoses
usually because infection is unsightly, not because lesions are painful
define the term keratinophyllic.
enzymes capable of breaking down keratin found in skin and hair
List the genus and species that are causes of superficial mycoses
Piedraia hortae
Trichosporon beigelii
Phaeoannellomyces werneckii
Malassezia furfur
Describe the types of infections caused by superficial mycoses
Causes;
Piedras and Tineas
Describe Piedras
means stone
hair infection where the nodules of fungal elements surrounds hair shaft. no discomfort or hair loss. does not involve the base of the shaft or follicle
Describe black piedra
-caused by Piedraia hortae
- occurs on scalp and forms nodules on hair
Lab ID of Piedraia hortae
Macroscopic- dark brown colonies
Microscopic- dematiaceous septate hyphae
Treatment of Piedraia hortae
removal of infected hair shafts with topical fungicides
Describe white piedra
caused by Trichosporon Beiglii
- occurs on facial and genital hair
- occasionally part of normal skin flora
- nodular swellings that weaken hair and cause it to break off
Lab ID of Trichosporon Beiglii
-causes white piedra
- presence of blastoconidia and arthroconidia
- produces creamy white yeast-like colonies on standard lab media
Treatment of Trichosporon Beiglii
shave area
Describe tineas
-infections of hair, nails, skin
-outermost cornified laryers of epidermis
Explain tinea nigra
-caused by Phaeoannellomyces werneckii
- palms of hands and soles of feet have brown to black nonscaly macules
- non inflammatory
- mold morphology
Lab ID of Phaeoannellomyces werneckii
-causes tinea nigra
- skin scraping in 10-20% KOH
- older mycelial portion of colony showing; hyphae with annellides in clusters
Explain tinea versicolor
caused by Malassezia furfur
- common skin flora
- parch lesions or scaling skin of varying pigments
- also described as fawn colored liver spots
- may have correlation between sun tan lotion and infections with yeast
- in light skinned people causes pink to dark brown patches
- in dark skinned people results in depigmentation
- yeast morphology
list Four infections caused by Malassezia furfur
pityriasis
Folliculitis
Seborrheic dermatitis
dandruff
Lab ID of Malassezia furfur
-causes tinea versicolor
- KOH preps of skin scrapings and with Wood's lamp- flourescence budding conidia (resembling yeast) along with septate hyphae
- in skin scrapings described as SPAGHETTI AND MEATBALLS FUNGI
Treatment for Malassezia furfur
Selsen Blue: 0.1% selenium sulfide
Define where in the body the cutaneous mycoses are found
Involves infection of skin, hair, nails, but also can penetrate to a deeper level
- involves the keratinized portion
- group of fungi called dermatophytes
- host defenses cause inflammation and discomfort
Name the Latin words used to define the location of the cutaneous mycoses and their meaning
Tinea pedis- athletes foot
Tinea cruris- jock itch
Tinea capitis- head
Tinea corporis- body
Describe Microsporum canis
-causes dermatophytoses
-Infection acquired from house hold pets
What three genera are responsible for most dermatophytoses
Trichophyton
Miscrosporum
Epidermophytom floccosum
Describe the the structures of the macroconidia and microconidia for Microsporum
Macroconidia- fusiform or spindle shaped (They taper out from center to both ends). Echinuluate- means prickly
-Microconidia- few, club shaped
Describe Microsporum gypseum
-causes dermatophytoses
- acquired from soil
- called a geophilic dermatophyte
Describe Microsporum audouini
-causes dermatophytoses
- common cause of tinea capitis in children
- called anthrophilic dermatophyte
Describe Epidermophyton floccosum
- causes athletes foot
Describe the structures of the macroconidia and microconidia for Epidermophyton
Macroconidia- paddle-like, beaver's tail, or snow shoe
Microconidia- never present
Describe the the structures of the macroconidia and microconidia for Trichophyton
Macroconidia- Rare, cylindrical, pensil shaped
Microconidia- numerous- comes in single (en thryses), clusters of grapes (en grappe), or spread out
Describe Trichophyton mentagrophytes
- most commonly encountered dermatophyte
describe T. tonsurans
LEADING CAUSE OF tinea capitis in children
three diseases that are caused by subcutaneous infections.
Sporotrichosis
Chromoblastomycosis
Eumycotic mycetoma
Define phaeohyphomycosis
general term referring to miscellaneous subcutaneous infections caused by dematiaceous fungi
For the fungus Sporothrix schenckii, give the common name for the disease and how it is acquired,
-Rose gardeners diseas
- resides in soil and is introduced by thorn pricks or wood splinters
- typically found in sphagnum moss
Explain why Sporothrix schenckii is a dimorphic fungus
- has two colony types at different temps
Room temp (25 C)- mold-form colony
- produces colonies initially white, glabrous (resembling pressed felt), and yeast like- as they grow older they turn darker
- Microscopically they have septate hyphae with conidia in shape of rosette

Body Temp (37 C)- yeast-form colony
- cigar shaped yeast like cells
For the fungi Phialophora, Fonsecaea, and Cladosporium, give the name of the disease they cause and the symptoms,
Cause Chromoblastomycosis
-verrucous (wart-like) dermatitidis
- may become elevated 1-3cm above surrounding tissue
- may spread to surrounding tissues through lymphatic system
- almost always on extremeties
- not painful unless there is a secondary bacterial infection
Descirbe Phialophora
flask shaped phialides with balls of conidia (tight bunch of flowers)
Describe Fonsecaea
various arrangements of conidia,
-primary secondary tertiary conidia
Describe Cladosporium
conidia resemble a wheat head
- only one that produces conidia in chains
For the fungus Pseudallescheria boydii, give the name of the disease it causes and the symptoms
-most common cause of eumycotic mycetoma in U.S.
- produces hyaline (white) granules in drainage from infection
- unique among fungi pathogenic for humans because its able to produce both sexually and asexually on culture media
Name two bacteria that can cause the same disease as Pseudallescheria boydii
-causes Actinomycotic mycetoma
- caused by Nocardia, Actinomyces, Streptomyces, and Actinomadura
Describe Eumycotic mycetoma
-swollen tumor-like areas with sinuses that drain through multiple sinus tracts
- pus contains "granules" composed of compact mycelia masses with white and black grains
Explain the term Perfect Fungi
- capable of sexual reproduction
- male nucleus and female cell fuse to form zygote called and ASCUS and walls itself off
-
Define Fungi Imperfecti
-only capable of asexual reproduction
What are the sexual spores within the ascus
Ascospores
-the nucleus in the ascus divides and produces these
- the ascus is now a sac containing ascospores
What are ascocarps
-Big sacs within a fungal structure that contain a number of asci
Define Ascomycota (ascomyces)
- A division of fungi that contains about 32,000 known species of molds and yeasts that are characterized by the formation of HAPLOID ASCOSPORES within sacs called ASCI
Define cleistothecium
a special type of ascocarp in Psuedallescheria boydii
- sealed off sac full that ruptures and spills out ascopores
Define systemic mycoses and at what temperatures cultures should be incubated
Pathogen usually inhaled into lungs which can spread to circulatory system
- infection involves organs and organ systems
- suspected material should be cultured at 37 C and 25 C since they are dimorphic fungi
List four fungi that cause systemic mycoses and the general term used to describe infection by each of the organisms.
1- Coccidoides immitis: Coccidioidmycosis
2- Histoplasma capsulatum: Histoplasmosis
3- Blastomyces dermatitidis: North American Blastomycosis
4- Paracoccidioides brasiliensis- South American Blastomycosis
For the fungus Coccidioides immitis, list three common names for the infection
- Valley fever
- Desert rheumatism
- San Joaquin Valley in California causes "Desert Bumps"
Symptoms for the fungus Coccidioides immitis
60% of time are asymptomatic and self-limiting
- more sever in dark skinned people and pregnant women
-severe cases cause progressive pulmonary disease
For the fungus Coccidioides immitis list areas of the U.S. where infection with the organism is endemic
-found in low rainfall and semi arid conditions
- California, Arizona, southern Utah, and New mexico
- 90% of population in endemic areas give a positive skin test
Describe the virulence of Coccidioides immitis
-Most virulent of all human mycotic agents
- Arthroconidia in the dust get inhaled where they convert to spherules that produce endospores
- the endospores ruture and produce spherules
For the fungus Histoplasma capsulatum, what is the common name for the disease, list where it is endemic and the symptoms of the infection
- histoplasmosis AKA "caves diesase" or "spelunkers disease"
endemic along the Mississippi river valley
- immunocompetent host is asymptomatic
- heavy exposure causes acute/chronic pulmonary disease
- potentially fatal disseminated disease
For the fungus Histoplasma capsulatum what are the zoophilic hosts
-pigeons and bats
For the fungus Histoplasma capsulatum explain how an individual acquires the fungus
-acquired by inhaling microconidia which once in lungs convert to yeast stage
- when phagocytized by macrophages in lungs the yeast becomes an intracellular parasite living in the macrophage
Lab ID for the fungus Histoplasma capsulatum
sample is a direct sputum or bronchial washing
- microscopically there are tiny yeast seen in monocytes
For the fungus Blastomyces dermatitidis, list where it is endemic and the symptoms of the infection
- North American Blastomycosis
-Endemic in Mississippi and Ohio river basins
May be manifested as
- disseminated disease from inhalation of conidia where flu like symptoms may progress to progressivve pulmonary disease
- Skin disease- where organism spreads and causes ulcerative lesions
Lab ID of Blastomyces dermatitidis
Candida that resemble lollipops
"blastomyces lollipops"
For the fungus Paracoccidioides brasiliensis, list where it is endemic and the symptoms of the infection
-South American Blastomycosis
- Rarely seen in North America
-causes cutaneous and mucosal lesions
Lab ID of Paracoccidioides brasiliensis
Budding yeast with multiple budding buds around central yeast cell
- looks like a "MARINERS WHEEL"
Define opportunistic mycoses
fungi that can cause infections that affect individuals who are significantly injured or debilitated
- these are the fungi that are most frequently isolated in the clinical lab
list three general groups of fungi that are involved in opportunistic mycoses
Yeasts
Zygomyces
Hyaline molds
List four genus and species that cause yeast infections
Candida albicans
Candida krusei
Candida tropicalis
Cryptococcus neoformans
Define blastoconidium
conidium produced by budding
Define pseudohyphae
blastoconidium that are connected and constricted at the ends
define chlamydospore
swollen cells which help yeast survive under harsh conditions
Explain carbohydrate assimilation method
detects oxidative and anaerobic fermentation
- commercial ID systems used like API 20C are specific for yeast ID
What is the plating media for fungi
Cornmeal Tween 80 Agar (CMT)
What structures will you see with Candida
Pseudohyphae, blastoconidia, and chlamydospores
What genus will lack pseudohyphae
Cryptococcus
What structures will you see with trichosporon
Arthroconidia, blastoconidia, and pseudohyphae
Explain the germ tube test
-A rapid test with one colony of yeat to 0.5 ml of sheep, horse, or human serum
- incubate at 35 C for 3 hours
- give accurate ID of C. albicans
- no constriction at base of germ tube= C. albicans
- constriction at base of germ tube= C. tropicalis
Name 3 diseases caused by Candida albicans
Thrush
vaginitis
localized skin infections, dissemination and septicemia
Describe vaginitis
-can follow antibiotic therapy since lactobacillus normally inhibits Candida
- produces a thick yellow discharge
Describe Thrush
Candida albicans infection of the oropharynx
- white creamy patches on tongue forming a pseudomembrane that looks like cottage cheese
- the material consists of masses of pseudohyphae
- removal of pseudomembrane leaves a raw, red base
For Cryptococcus neoformans, explain how an individual would contract the organism
Infection by inhalation of pigeon fecal flora
- causes pulmonary infection and can cause meningitis in immunocompromized
- very common in AIDS patients
List two laboratory identification methods for detecting Cryptococcus neoformans
Capsular crytococcal antigen
- this is a latex agglutination test
- test of choise since it's the only pathogenic yeast that has a capsule

India Ink and microscopic exam
- previously used and showed a contrast of the capsule
List the characteristics of the Zygomycetes.
-Aseptate hyaline molds
- rapid growing
- Perfect fungi; capable of sexual and asexual reproduction
Explain the asexual and sexual repro of zygomycetes
Asexual -sporangial sporulation

Sexual- occurs between compatible mating strains with produciton of zygospores by fusing together
Most commonly encountered genus of fungi in the clinical lab?
Aspergillus fumigatus
List 3 genera of zygomycetes
Absidia
Mucor
Rhizopus
What does Penicillium resemble
paint brush
- has branched conidiohphore at the base of the "brush head"
Define saprobes or saprophytes
organism that lives on dead organic material and are enriched by the nitrogenous matter
What are fungal cell walls made of
Chitin
What gives molds their fuzzy or woolly appearance
mycelium which is made of hyphae
What are hyphae
tube like structures that have an optimum growth temp of 20-30 C
Define pseudohyphae
chains of budding yeast
define hyaline
light pigment
Dematiaceous
dark pigment due to presence of melanin
septate hyphae
have frequent cross walls between cells
define wet mount
a suspension of the specimen on a slide with a cover slip
What does KOH do
dissolves most cellular debris, like keratin, without affecting chitinous cell wall of fungus
What does KOH with calcoflour white do
binds to chitin and flouresces making fungal elements appear as "apple green" or white with reddish background
What is SDA
Sabouraud Dextrose Agar
- medium most often used, supports growth of almost any fungus
What antibiotics are in some SDAs
Chloramphenicol
Cyclohexamide
What is BHIA
Brain-Heart Infusion Agar
- supports growth of the yeast phase of the dimorphic fungi
What is LPCB
Lactophenol-Cotton Blue
- preferred stain for microscopic examination of mold-form colonies
Conidia
Conidium (singular)
Asexual reproductive structures
found in phialides or annellides
Phialide
vase-like structures that produce and contain many conidia located on a conidiophore
annellide
ringed structure that produce and contain a single conidium
- looks kind of like a bowling pin
- located on an annellophore
arthroconidia
fragmented hyphae produced by asexual repro
sporangiospores
asexual spores formed only is aseptate fungi
Sporangium
saclike structure in which sporagniospores are formed
- located on a sporangiophore
What 2 fungi make up the Hyaline Molds
Aspergillus fumigatus
Penicillium species