Identification of Candida species by restriction enzyme analysis

Abstract number: P725

Yis R., Yücesoy M.

Background: Identification of Candida species isolated from clinical specimens gives information about the antifungal susceptibility as well as sheds light to the choice of empirical treatment.

Objectives: This study was planned to apply restriction enzyme analysis (REA) for more rapid and reliable identification of Candida albicans and non Candida albicans species which had been previously identified by conventional methods and to compare the results.

Methods: In this study 146 Candida strains (40 C. albicans, 27 C. parapsilosis, 26 C. tropicalis, 25 C. glabrata, 11 C. kefyr, 10 C. krusei, and seven C. guilliermondii) isolated from various clinical specimens and C. albicans ATCC 14053, C. parapsilosis ATCC 90018 and C. krusei ATCC 6258 were included. The strains were identified according to germ tube test, morphology at cornmeal tween 80 agar and CHROMagar Candida and API 20C AUX system.

PCR was performed by using primers which targeted ITS1, 5.8S rDNA and ITS2 regions. PCR products were digested with MwoI enzyme for all species and with BslI for C. parapsilosis and C. tropicalis strains. Sequence analysis of four C. albicans and two C. guilliermondii isolates which resulted in different restriction patterns was performed.

Results: Calculated lengths of REA products obtained by MwoI enzyme are presented in the table. Restriction of C. parapsilosis and C. tropicalis isolates with BslI resulted in three bands of 413, 94 and 63 bp and three bands of 326, 187 and 63 bp, respectively. Three C. albicans isolates which produced a different restriction pattern had point mutations (guanine instead of adenine); one isolate had insertion/deletion type mutation and these mutations were the reason of a different pattern. In addition, sequence analysis of two C. guilliermondii isolates showing various fragments with different lengths were 66.6% similar with GenBank C. guilliermondii var. guilliermondii and 91.2% similar with C. guilliermondii var membranaefaciens (nucleotide seqeunce). Because of this high nucleotide sequence similarity, these isolates were accepted as C. guilliermondii var membranaefaciens.

Conclusion: As a result, we can conclude that restriction enzyme analysis with MwoI and BslI enzymes can be used for the identification of Candida species which need rapid identification or which are problematic with conventional methods that are still accepted as gold standard although some variations can be observed with this method.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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