Mycology

Question 1

Which Trichophyton fungi have a thiamine requirement?

Answer 1

Trichophyton violaceum and Trichophyton tonsurans

Question 2

Which organism poses the greatest risk for laboratory workers?

Answer 2

Coccidiodes immitis

Question 3

Which organism is round to oval, yeast-like microorganism, +/- for a capsule, produces blastospores but no pseudohyphae and assimilates inositol?

Answer 3

Cryptococcus neoformans

Question 4

What yeast-like organism requires an oil layer? What disease does it cause?

Answer 4

Malassezia furfur. Causes Tinea versicolor (brown patches on chest and back). Woods lamp positive

Question 5

What test would you use to distinguish Trichophyton mentagrophytes and Trichophyton rubrum? What are the results?

Answer 5

Use the hair-perforation test. T. mentagrophytes is positive. T. rubrum is negative.

Question 6

What stain is good for Cryptococcus neoformans?

Answer 6

India ink and wrights. NOT Gram stain.

Question 7

What media is used to produce Chlamydospores?

Answer 7

Cornmeal tween 80, Chlamydospore agar

Question 8

What is the test of choice to diagnose Cryptococcus neoformans?

Answer 8

Latex Agglutination

Question 9

What is the test of choice to diagnose Coccidiodes immitis?

Answer 9

Comp Fixation

Question 10

What is the main difference between anamorph and telomorph?

Answer 10

Anamorph is an asexual reproductive stage, often mold-like. Telomorph is the sexual reproductive stage, typically a fruiting body.

Question 11

What is the difference between Rhizopus and Mucor?

Answer 11

Rhizopus is round sporangium with rhizoids opposite where the sporangiophores arise. Mucor is sporangiospores that are singularly produced or branched. No rhizoids or stolons.

Question 12

What is the description of Penicillium?

Answer 12

Branching/Medula

Question 13

What is the description of a philaphora?

Answer 13

Vase-shaped with collarette.

Question 14

What is the characteristic that proves a fungus is Coccidiodies immitis?

Answer 14

Barrel-shaped alternating arthroconidia, Sporangia=Spherules filled with endospores in tissue. Found in San Joaquin Valley (SW US).

Question 15

What is 10% KOH used for?

Answer 15

Used to break down debris and clearing agent

Question 16

What dermatophytes are anthrophilic?

Answer 16

Trichophyton

Question 17

What are the microscopic characteristic of dermatophytes/microsporidium?

Answer 17

Lots of macroconidia, few microconidia. Echinulate (rough) macroconidia. Pyriform (spindle shaped) microconidia.

Question 18

What are the characteristics of Blastomyces dermatitidis?

Answer 18

Broad-base budding. Ohio and Mississippi River valleys. Inhibited by cycloheximide.

Question 19

What are some biochemical characteristics for Crytpococcus neoformans?

Answer 19

Positive urease, positive india ink.

Question 20

Trycophyton rubrum is characterized by what?

Answer 20

Wooly, reverse with diffusible red pigment, hair-perforation test negative.

Question 21

Phenol oxidase of Cryprococcus neoformans can be demonstrated by what?

Answer 21

Bird seed agar or caffeic acid agar.

Question 22

If Trichophyton rubrum is growing on a sabdex plate, does it need thiamine to grow?

Answer 22

No.

Question 23

Define phialide.

Answer 23

A cell that produce and extrudes conidia. The tip is bottle-shaped and does not taper or lengthens as each conidium is released.

Question 24

Define annelide.

Answer 24

A cell that produce and extrudes conidia. The tip tapers and lengthens as each conidium is released.

Question 25

Coccidiodes spherules without mature endospores may be confused with which organism?

Answer 25

Geotrichum