Comparison of Vitek-2 automated identification system and PCR-ITS for species characterization of clinical isolates of Candida spp

Abstract

Serious infections caused by genus Candida have become a challenge in the diagnostic question, in order to detect and identify the etiologic agent of agile, precise and standardized form in manner clinical laboratories. The prediction of susceptibility to antifungal agents, and the need to generate epidemiological data highlight the importance of routine identification of yeast species involved in infections. Among the 200 Candida species already described, C. albicans, C. parapsilosis, C. tropicalis, C. glabrata, C. guilliermondii, C. krusei and C. lusitaniae are most often related with infections in humans. All of the phenotypic methods of identification of Candida have limitations, especially the characterization of the species not C. albicans, however, the application of molecular methods may reflect the increased cost and spent time for obtain results on laboratory. In order to evaluate the implementation of the automated system Vitek 2 ID - YST (bioMerieux) combined with the use of chromogenic agar in the routine identification of Candida species were tested 44 isolates from invasive infection by inoculation of chromogenic agar and automated panel and realization DNA amplification for the internal transcribed spacer regions of rRNA 1 and 2 (ITS - PCR). Oligonucleotides specific species were used and the size of the amplified product was correlated to other results. The automated system identified 95.4 % of the isolates when in association with colonial features observed in chromogenic medium, however, the use of PCR -ITS or more sensitive methodologies would be needed to solve the other results, ambiguous and erroneous.