Deck 61: The Yeasts

Question 1

Tinea versicolor is a skin infection characterized by superficial brownish scaly areas most often on the trunk,arms,or shoulders.Which type of replacement therapy places patients at risk for developing this type of skin infection?

A)Hormone
B)Lipid
C)Saccharide
D)Gene

Answer 1

B
Malassezia furfur causes tinea versicolor,a skin infection that is characterized by superficial brownish scaly areas on light-skinned persons and lighter areas on dark-skinned persons.The lesions occur on the smooth surfaces of the body,specifically,the trunk,arms,shoulders,and face.It has a worldwide distribution.M.furfur is also a cause of disseminated infection in infants and young children and in adults taking lipid replacement therapy.

Question 2

A fungal infection found mostly in the tropics and temperate regions is characterized by the development of soft,yellow or pale-brown aggregations around hair shafts in the axillary,facial,genital,and scalp regions.The fungus that would most likely be isolated is:

A)Candida.
B)Malassezia.
C)Cryptococcus.
D)Trichosporon.

Answer 2

D
White piedra caused by Trichosporon spp.is an uncommon fungal infection in patients who are immunocompetent and is found in both tropical and temperate regions of the world.It is characterized by the development of soft,yellow or pale-brown aggregations around hair shafts in the axillary,facial,genital,and scalp regions of the body.The Trichosporon spp.that causes this disease frequently invades the cortex of the hair and causes damage.

Question 3

A patient with leukemia is diagnosed with a Candida infection after receiving several doses of chemotherapy.The most likely yeast causing the infection is:

A)C.albicans.
B)C.parapsilosis.
C)C.tropicalis.
D)Candidametapsilosis.

Answer 3

C
C.tropicalis has been shown to be prevalent in patients with hematologic malignancies,especially those with neutropenia.

Question 4

Cryptococcus neoformans is widely distributed in nature,and aerosolization is a prerequisite to most infections.This organism is most often associated with exposure to:

A)contaminated soil.
B)pigeon excreta.
C)contaminated food.
D)rat excreta.

Question 5

If cornmeal agar is set up and chlamydoconidia are produced,the organism is most likely:

A)C.krusei.
B)C.glabrata.
C)C.albicans.
D)C.tropicalis.

Question 6

MATCHING
Match the organism with its characteristics.
a.Trichosporon spp.
b.C.albicans
c.M.furfur
d.C.neoformans
Polysaccharide capsule

Question 7

MATCHING
Match the organism with its characteristics.
a.Trichosporon spp.
b.C.albicans
c.M.furfur
d.C.neoformans
"Spaghetti and meatball" morphologic appearance

Question 8

A patient with acquired immunodeficiency syndrome (AIDS)notices skin lesions on his back that have begun to ulcerate.Upon physical examination,his physician also notices hepatomegaly that is most likely caused by hepatitis.The physician prescribes antifungal therapy to prevent the dissemination of which of the following yeasts?

A)C.albicans
B)C.neoformans
C)C.glabrata
D)C.tropicalis

Question 9

Blood cultures are drawn on a patient suspected of having a fungemia.Positive cultures reveal the presence of chlamydoconidia on cornmeal agar.In addition,the yeast is germ tube positive.The most likely identification of the fungal agent is:

A)C.glabrata.
B)C.tropicalis.
C)C.neoformans.
D)C.albicans.

Question 10

MATCHING
Match the organism with its characteristics.
a.Trichosporon spp.
b.C.albicans
c.M.furfur
d.C.neoformans
White piedra

Question 11

Agar medium overlaid with olive oil will enhance the growth of which organism?

A)Malassezia
B)Candida
C)Trichosporon
D)Cryptococcus

Question 12

The most commonly isolated yeast in clinical specimens is:

A)Candida albicans.
B)Candida tropicalis.
C)Candida dubliniensis.
D)Candida krusei.

Question 13

Encapsulated yeast is identified in the cerebrospinal fluid (CSF)of a patient with AIDS.The most likely stain or reagent used to identify this organism is:

A)potassium hydroxide (KOH).
B)calcofluor white.
C)lactophenol cotton blue.
D)India ink.

Question 14

Determining urease activity and growth on niger seed agar is helpful in determining which type of yeast?

A)C.albicans
B)Trichosporon
C)C.neoformans
D)M.furfur

Question 15

In general,yeast reproduces asexually by the formation of:

A)ascospores.
B)basidiospores.
C)blastoconidia.
D)arthroconidia.

Question 16

MATCHING
Match the organism with its characteristics.
a.Trichosporon spp.
b.C.albicans
c.M.furfur
d.C.neoformans
Creamy,white patches

Question 17

Which yeast identification system uses chromogenic substrates to assess specific enzyme activity usually detected within 4 hours?

A)Vitek
B)MicroScan
C)API-20C AUX
D)Uni-Yeast-Tek

Question 18

A patient with diabetes is experiencing creamy patches on his tongue and mucous membranes.Cultures are performed,and yeast is recovered.His diagnosis is most likely:

A)paronychia.
B)onychomycosis.
C)candidemia.
D)thrush.