Performance evaluation of Vitek 2 AST-YS08 for antifungal susceptibility testing of yeast: a categorical agreement study with Liofilchem mic strips with 22 clinical samples in Hospital Sultanah Aminah, Johor Bharu and Hospital Pakar Sultanah Fatimah, Muar

Kai Jie Yow^1*, Yii Ling Liow², Farah Nooraidil², Dayangku Seritul Akmar Abd Razak², Nian Jye Tey³, Mohan Rao Nageswara Rao⁴

1. Unit of Microbiology, Department of Pathology, Hospital Segamat, 85000 Segamat, Johor, Malaysia
2. Unit of Microbiology, Department of Pathology, Hospital Sultanah Aminah Johor Bahru, 80100 Johor Bahru, Johor, Malaysia
3. Unit of Microbiology, Department of Pathology, Hospital Pakar Sultanah Fatimah Muar, 84000 Muar, Johor, Malaysia

*Corresponding author: Kai Jie Yow. This email address is being protected from spambots. You need JavaScript enabled to view it.. Tel: +607 9433333

CITATION: Yow KJ, Liow YL, Nooraidil F, Abd Razak DSA, Tey NJ, Nageswara Rao MR. Performance evaluation of Vitek 2 AST-YS08 for antifungal susceptibility testing of yeast: a categorical agreement study with Liofilchem mic strips with 22 clinical samples in Hospital Sultanah Aminah, Johor Bharu and Hospital Pakar Sultanah Fa􀆟mah, Muar. International Medical Research Journal. 2025 May 30;11(1):84–97. https://doi.org/10.63719/imrj.2025.11.01.008

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ABSTRACT
Invasive fungal infections caused by Candida spp. and Cryptococcus neoformans present significant clinical challenges. This study evaluates the Vitek 2 AST-YS08 system against Liofilchem MIC strips to determine minimal inhibitory concentrations (MICs) of fungal agents in two hospitals in Johor. A total of 22 clinical isolates from Candida spp. and Cryptococcus neoformans were tested. MIC values for antifungals were determined via the Vitek 2 system and Liofilchem MIC strips. Results were compared for concordance using the latest Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. The Vitek 2 system demonstrated an overall categorical agreement of 91% with MIC strips. Categorical agreements were achieved for all isolates of C. albicans, C. parapsilosis, C. guilliermondii, and Cryptococcus neoformans. Lower concordance rates were observed for C. tropicalis (80%) and C. glabrata (75%). Two discrepancies were identified in Sample 5 (C. glabrata), micafungin MIC values differed between systems (0.006 μg/mL vs. 0.12 μg/mL), and in Sample 16 (C. tropicalis), fluconazole MIC values varied (1 μg/mL vs. 8 μg/mL). The Vitek 2 method provides quick results and matches well with manual testing. The discrepancy of the results with different methods may affect the treatment outcome for the patient. The system's automation and efficiency make it a valuable tool for high-throughput clinical microbiology laboratories. The Vitek 2 AST-YS08 system is a fast and reliable way to test the antifungal sensitivity of yeast. More studies are needed to improve its use in different medical situations.

KEYWORDS: Antifungal susceptibility testing, Candida spp., Cryptococcus neoformans, minimal inhibitory concentration (MIC), automated AS