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Microbiology

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Mycology

Question
40 out of 103
 

C. albicans is best described by which of the following statements?



A Round, black sporangia filled with endospores; sporangia unbranched, rising from a runner called a stolon

B Single-tipped sporangiophores; no rhizoids or stolons; nonseptate hyphae, which show branching.

C Widespread in environment; candida may be inhaled; microscopic appearance in specimen reveals dichotomous branching and septate hyphae.

D Yeast forms with budding blastoconidia often showing pseudohyphae; positive germ tube test; chlamydospores present.

Ans. D Yeast forms with budding blastoconidia often showing pseudohyphae; positive germ tube test; chlamydospores present.

a. Candidiasis is the most frequent opportunistic infection.

b. While C. albicans is most commonly isolated, other species such as C. tropicalis and Torulopsis glabrata are also seen.

c. The yeasts may be identified biochemically, but C. albicans is distinctive in that it produces germ tubes and chlamydospores.

d. Option c- Aspergillosis, caused by a number of species of Aspergillus, is characterized in direct smear by septate hyphae, dichotomously branched. Aspergillus Flavus and A.

e. fumigatus are often seen as saprophytes in the lab oratory but also account for the major species isolated from patients with aspergillosis.

f. Differentiation of species, as with the zygomycetes, is dependent upon isolation of the fungus and precise morphological examination.

g. Zygomycosis, a term referring to infection by members of the class Zygomycetes, is caused primarily by Rhizopus, Mucor and Absidia.

h. Other zygomycetes such as Basidiobolus and Cunninghamella are rarely encountered. The lack of septate hyphae on a direct smear may be the initial hint of zygomycosis.

i. However, not uncommonly, the occasional hypha of Mucor will have a septa. The genera cannot be differentiated on a direct patient specimen.

j. The organism must be isolated and slide cultures performed to observe the characteristic morphology of these filamentous fungi.

k. Rhizopus species (option a) have sporangia that arise from a stolon, while Mucor species (option b) do not. Mucor species have collarettes; Rhizopus species do not.

Mycology Flashcard List

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