Objective: The species of Candida are the major cause of invasive fungal infections in hospitalized patients. Identification of yeasts to the species level has become a priority, not only for the increasing number of non-Candida albicans isolates but also for the differential susceptibilities to antifungal agents, being important at this point for the therapeutic management. VITEK 2 (BioMe’rieux, Inc, Hazelwood, MO, USA) is a fully automated microbiology instrument that allows the identification of microorganisms, including yeasts. This study utilized ID-YST card using a colorimetric system which include 47 biochemical tests (a variety of carbohydrate and organic acids assimilation tests, oxidase and arilamydase enzyme detection). The aim of our study was to evaluate the YST card of VITEK 2 System for the identification of the most frequent yeasts in clinical microbiology laboratory. Methods: A total of 168 strains of Candida were studied: C. albicans (n = 26), C. tropicalis (n = 29), C. glabrata (n = 28), C. parapsilosis (n = 32), C. krusei (n = 26), C. guilliermondii (n = 20), C. dubliniensis (n = 7); 164 isolates came from clinical samples of hospitalized and ambulatory patients received in hospitals included in the Mycology Net of Buenos Aires, Argentina. Four pattern strains: C. parapsilosis ATCC 22019, C. krusei ATCC 6258, C. glabrata ATCC 90030 and C. albicans ATCC 64548 were included. The strains were transferred from storage at )70C onto Sabouraud agar and subcultured after 24 hour on Sabouraud agar. All strains were tested with the ID-YST card and API 20C or API 32C system (BioMe’rieux, Marcy L’Etoile, France), according the manufacturer’s instructions and the results were compared. The API was considered the reference standard for accuracy of identification. Results: The percentage of concordance between API and VITEK 2 Yeast card was 98.3%. There were three misidentifications: one C. parapsilosis, one C. krusei and one C. tropicalis. The average time of identification was 18.2 hour (range 18.0-18.5 hour). Conclusions: According to the results of our study VITEK 2 System is a reliable, simple and effective method for the identification of the most frequent Candida spp and besides, reduced the times for identification from 48 to 18 hour.
Full conference title:
22nd European Congress of Clinical Microbiology and Infectious Diseases
- ECCMID 22nd (2012)