Question
The image is shown of a dimorphic fungus, inhabiting 80% of intestinal tract, colon, and mouth and which is the most common cause of fungal infections worldwide.One of its species shows positive Germ Tube test.Identify this fungus .
A. Coccidiomycosis.
B. Penicillium.
C. Candida.
D. Aspergillus.
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Correct Answer » C Explanation |
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Ans: C. Candida
The fungus shown in the photograph above represents candida.
Candida
- It is a genus of yeasts and is the most common cause of fungal infections worldwide.
- Candida albicans is the most commonly isolated species.
- C. albicans is a diploid fungus populating the human body worldwide, inhabiting 80% of everyone’s intestinal tract, colon, and mouth with no problems.
- It is normally commensal of humans but can be pathogenic if a person’s immunity is lowered or there is a change in natural flora or physiology.
Morphology:
- It is dimorphic.
- C. albicans can take on either a unicellular (yeast) or multicellular (hyphae, pseudohyphae) form.
- In Gram stained smears, Candida appears as gram positive budding yeast cells (blastoconidia) and/or pseudohyphae showing regular points of constriction.Spores form on the pseudohyphae called chlamydospores
Culture:
- Candida appears as large, round, white or cream colonies, which emit a yeasty odor on agar plates at room temperature.
- Germ tube positive:A rapid method of identifying C. albicans is based on its ability to form germ tubes within two hours when incubated in human serum at 37°C Reynolds – Braude phenomenon ( Also known as germ tube test)