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Volume 43, Number 2, April 2010

Comparison of Phenotypic Methods for the Identification of Candida dubliniensis


Julia Pasligh, Clarissa Radecke, Michael Fleischhacker*, Markus Ruhnke Division of Oncology, Department of Medicine, Charit. Universit.tsmedizin Berlin, Charit. Campus Mitte, Berlin, Germany


Received: September 2, 2008    Revised: October 8, 2008    Accepted: November 7, 2008   

 

Corresponding author:

 

E-mail: michael.fleischhacker@charite.de


 

Background and purpose: 

Mixed infections caused by different Candida species are the rule rather than the exception. The discrimination between the two closely related species Candida albicans and Candida dubliniensis is not trivial. Therefore, there is a need for fast, reliable, and inexpensive methods with high specificity for the identification and differentiation of these two Candida species, which are frequently detected in the oral cavities of patients with a human immunodeficiency virus infection.



 

Methods:

We applied several phenotypic identification methods (growth on Rice-agar, Bird-seed agar, CHROMagar(R) Candida, API ID 32C; growth at 42.C and 45.C) and compared them with genotyping by arbitrarily primed-polymerase chain reaction.



 

Results:
A sensitivity of 44% for the identification of C. dubliniensis was achieved for growth on Rice-agar, 97% for discrimination on Bird-seed agar, 95% with the assimilation profile index API ID 32C, and 97% when grown at 45.C. We found two API codes not described for C. dubliniensis so far. Additionally, 88% of our 
C. dubliniensis isolates assimilated palatinose, in contrast to the 1% described in the API reference manual. CONCLUSION: According to our results, cultivation of Candida isolates on Bird-seed agar after screen-ing on CHROMagar(R) Candida is a very sensitive, simple, and cost-effective method for discriminating 

C. dubliniensis from C. albicans in routine practice. 



 

Key words:

API ID 32C, AP-PCR, Bird-seed agar, Candida dubliniensis, CHROMagar(R) Candida