Appropriate Condition of Germ Tube Formation as Presumptive Identification Test for Candida albicans

Park, Borae G; Lee, Mi Kyung

Abstract

BACKGROUND: Candida albicans is the most prevalent species found in human yeast infections. The germ tube test is still frequently used for its rapid presumptive identification. Recently Candida dubliniensis as well as C. albicans has been reported to form germ tubes. OBJECTIVE: The purpose of this study was to evaluate the germ tube test at various conditions for rapid presumptive identification of C. albicans.
METHODS
C. albicans ATCC 14053, C. albicans ATCC 18804, C. dubliniensis ATCC MYA 646, and C. dubliniensis KCTC 17427 were tested. Human pooled serum (HPS), HBV, HCV infected patient serum, fetal bovine serum (FBS) and rabbit serum (RS) were used for germ tube test. The germ tube formation was evaluated at different keeping condition of various sera, after mixing with 5 different bacterial suspensions and at various incubation conditions.
RESULTS
The germ tube formation of C. albicans was more in the RS or FBS than in the HPS. For the various sera fresh sample was always the best expression of germ-tube forming ability. In the HCV infected patient serum and mixing with Pseudomonas aeruginosa germ tube formation was suppressed. C. dubliniensis did not form germ tube in the HPS, only formed in the FBS or RS.
CONCLUSION
For rapid presumptive identification of C. albicans not C. dubliniensis the best selection of serum is the fresh HPS. We recommend the examination with isolated colony free from bacteria after incubation for 2 to 3 hours.