Original Article


Korean J Clin Microbiol. 2009 Sep;12(3):122-128. Korean.
Published online September 30, 2009.  https://doi.org/10.5145/KJCM.2009.12.3.122
Copyright © 2009 The Korean Society of Clinical Microbiology
Evaluation of VITEK-2 Antifungal Susceptibility Test (AST-YS01) for Candida Species Isolates in Korea
Da-Woon Kim, Jong Hee Shin, Seung Jung Kee, Soo-Hyun Kim, Myung Geun Shin, Soon Pal Suh and Dong Wook Ryang
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.

Correspondence: Jong Hee Shin, Department of Laboratory Medicine, Chonnam National University Medical School, 671, Jebong-ro, Dong-gu, Gwangju 501-757, Korea. (Tel) 82-62-220-5342, (Fax) 82-62-224-2518, Email: shinjh@chonnam.ac.kr
Received April 20, 2009; Revised June 05, 2009; Accepted July 15, 2009.



Abstract

Background

VITEK-2 yeast susceptibility test (AST-YS01; bioMerieux, Hazelwood, MO, USA) has recently been introduced as a fully automated commercial antifungal susceptibility test system that determines MIC (minimum inhibitory concentrations) endpoints spectrophotometrically, thereby eliminating subjective errors. We compared the VITEK-2 system with the CLSI (the Clinical and Laboratory Standards Institute) M27 method for susceptibility testing of Candida isolates from Korea.

Methods

A total of 175 Candida bloodstream isolates were collected from two hospitals during a 18-month period. We compared the MIC results for amphotericin B, fluconazole and voriconazole obtained with the VITEK-2 system to those obtained by the CLSI M27 broth microdilution method after 24-hr and 48-hr incubation.

Results

VITEK-2 system MIC endpoints for 175 isolates were determined after 11.75 to 35.50 hr of incubation (mean, 16.3±4.8 hr). The essential agreement (within 2 dilutions) between amphotericin B, fluconazole and voriconazole MICs obtained by the VITEK-2 system and CLSI method was 98.3%, 90.9% and 96.0%, respectively, at 24-hr incubation and 100%, 92.6% and 94.9%, at 48-hr incubation. The categorical discrepancy for fluconazole was 6.3% (major error, 2.9% and minor error, 3.4%) at 24-hr and 6.3% (major error, 2.3% and minor error, 4.0%) at 48-hr. The categorical discrepancy for voriconazole was 1.7% (major error, 1.1% and minor error, 0.6%) at both 24-hr and 48-hr. There were no very major errors for fluconazole and voriconazole.

Conclusion

The VITEK-2 antifungal susceptibility test system appears to be rapid and highly correlative with the CLSI method, sugesting that this system can be effective for antifungal susceptibility testing for Candida species in the clinical laboratory.

Keywords: Candida; VITEK-2; Antifungal susceptibility; CLSI

Tables


Table 1
In vitro susceptibilities of 175 isolates of Candida spp. to amphotericin B, fluconazole and voriconazole as determined with the VITEK-2 system and by CLSI BMD methods
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Table 2
Categorical agreement between the fluconazole and voriconazole MICs determined by VITEK-2 system and CLSI 24-hr and 48-hr BMD method for 175 isolates of Candida spp.
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Table 3
Testing results for 14 Candida isolates showing a categorical disagreement of antifungal MIC results between VITEK-2 AST-YS01 and CLSI BMD method
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