Misidentification ofCandida guilliermondiiasC. famataamong Strains Isolated from Blood Cultures by the VITEK 2 System

Abstract

Introduction. The aim of this study was to differentiate betweenCandida famataandCandida guilliermondiicorrectly by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and gene sequencing.Methods. Twenty-eightCandidastrains from blood cultures that had been identified asC. famata(N=25),C. famata/C. guilliermondii(N=2), andC. guilliermondii(N=1) by the VITEK 2 system using the YST ID card were included. We identified these strains by MALDI-TOF MS and gene sequencing using the 28S rRNA andITSgenes and compared the results with those obtained by the VITEK 2 system.Results. All 28 isolates were finally identified asC. guilliermondii.Sequencing analysis of the 28S rRNA gene showed 99.80%–100% similarity withC. guilliermondiifor all 28 strains. TheITSgene sequencing of the strains showed 98.34%–100% homology withC. guilliermondii.By MALDI-TOF, we could correctly identify 21 (75%) of 28C. guilliermondiiisolates.Conclusion. We should suspect misidentification whenC. famatais reported by the VITEK 2 system, and we always should keep in mind the possibility of misidentification of any organism when an uncommon species is reported.