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Bacteriology exam2


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What 2 species will form a germ tube? How may they be differentiated?
Candida albicans
C. stellatoidea

C. albicans is sucrose positive, while C. stellatoidea is sucrose(-)
This differentiates pseudohyphae from true hyphae?
constrictions between adjacent cells
The most common example of dermatophytosis is -
What 3 genera comprise the deratophytes?
Microsporum, Trichophyton, and Epidermiphyton
In a lesion formed by ringworm would it be more beneficial to take a sample from the edge or from the center of the lesion?
from the center
This yeast is commonly associated with otitis externa-
Malassezia pachydermatis
The key membrane lipid in fungi is -
T/F Griseofulvin is active against a wide range of fungi
False - Griseofulvin is only effective agains dermatophytes
Where is griseofulvin concentrated?
newli formed cells of skin, nails, and hair
Griseofulvin prevents mitosis by interfereing with what?
Mitotic spindle formation
T/F Resistance to Griseofulvin is uncommon
Amphotericin B has ___________ action.

A) Fungistatic
B) Fungicidal
Amphotericin B toxicity is likely to be seen in

A) Liver
B) Heart
C) Lungs
D) Kidney
D) Kidney - nephrotoxicity
Explain the 2 mechanisms of action of 5-FC (Flucytosine)
1) Converted to 5-fluorouracil which replaces RNA in the cell
2) 5-FU converted to 5-fluorodeoxyuridine monophosphate which inhibitds thymidine producion neccesary for DNA synthesis.
Since 5-FU is the active form why is 5-FC (Fluocytosine) used.
5-FU is not taken up by fungi and is toxic to mammalian cells
Why are 5-FC and Amphotericin-B often used in combination?
Less Amphotericin is neccesary and amphotericin makes the fungal cell wall more permeable to 5-FC

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