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Evaluation of commercial phenotypic identification systems for the characterisation of common and rare yeast pathogens

Abstract number: P904

Meletiadis J., Arabatzis M., Tsiveriotis K., Bobola M., Zerva L., Velegraki A.

Objectives: Yeasts are commonly implicated in superficial skin and mucosal infections in the community as well as in invasive infections in immunocompromised and seriously ill patients. Their identification to species level can have consequences for the diagnosis, epidemiology and treatment choice. Various automated systems are commercially available but few have been systematically tested with strains identified by molecular methods. The aim of the study was the evaluation of three main automated yeast identification systems, using for the first time local clinical strains.

Methods: 93 clinical isolates (comprising 24 species) were identified by the VITEK 2 system, Auxacolor KAI API ID32C. The results were compared to the reference identification method that employed sequencing of ribosomal regions.

Results: From the 61 strains belonging to the clinically most common species C. albicans, C. parapsilosis, C. tropicalis, C. glabrata, C. lusitaniae and C. krusei, Auxacolor correctly identified 95.1% of the strains, VITEK 2 90.2% and API ID32C 86.9%. From the 32 strains of rare species, the corresponding percentages were 43.8% (Auxacolor), 71.9% (VITEK 2) and 87.5% (API ID32C).

Conclusion: Auxacolor seems to be an excellent tool for screening common yeasts in the clinical laboratory. Rapid and fully automated identification was achieved by VITEK 2 (18 h versus 48–96 h for Auxacolor and API ID32C respectively). Generally, API ID32C and VITEK 2 were equally effective. No system could identify all uncommon, clinically relevant, non-C. albicans species. Consequently, these strains should be polyphasically identified by a combination of biochemical, physiological, morphological and genomic studies.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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