Candida albicans is distinguished from other Candida species by which two laboratory tests that can be performed rapidly in the clinical microbiology laboratory?
- A Positive germ tube test in serum at 37°C within 2–3 hours AND chlamydospore formation on cornmeal agar ✓
- B Growth at 45°C and production of urease
- C Positive oxidase test and fermentation of sucrose
- D Formation of pseudohyphae on sheep blood agar and growth on CHROMagar (blue colonies)
Correct answer: A. Positive germ tube test in serum at 37°C within 2–3 hours AND chlamydospore formation on cornmeal agar
Explanation
C. albicans is uniquely identified among Candida species by: (1) positive germ tube test — when incubated in human or animal serum at 37°C for 2–3 hours, C. albicans produces true germ tubes (hyphae with no constriction at point of origin), positive in ~95% of strains; and (2) formation of characteristic thick-walled terminal chlamydospores on nutrient-poor cornmeal Tween-80 agar at 25°C. C. dubliniensis also forms germ tubes and chlamydospores but cannot grow at 45°C. CHROMagar shows C. albicans as light green (not blue) colonies.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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