Germ tube test

Identification of yeasts As dermatophytes, yeast colonies are examined for macroscopic and microscopic criteria. C. albicans, the most prominent fungus of this group, may be identified by the presence of terminal chlamydospores on rice agar and of germ tubes after 2 h of incubation in serum at 37 °C ( germ tube test ). Besides classical tests for the specific identification of yeasts [3], several kits working with biochemical reactions are commercially available. 

Until recently, a rapid presumptive identification of C. albicans could be made by incubation of the organism in serum formation of a germ tube (the beginning of hyphae, which arise as perpendicular extensions from the yeast cell, with no constriction at their point of origin) within 1 to 2 hours offered a positive identification of C. albicans. Unformnately, C. dubliniensis, a new species of Candida that was identified recently as an important cause of mucosal colonization and infection in HIV-infected individuals, also can produce a germ mbe. A negative germ tube test does not rule out the possibility of C. albicans, but further biochemical tests must be performed to differentiate between other non-albicans species. ... 

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