Misidentification of Candida guilliermondii as C. famata among Strains Isolated from Blood Cultures by the VITEK 2 System

• Main Authors: Si Hyun Kim, Jeong Hwan Shin, Jeong Ha Mok, Shine Young Kim, Sae Am Song, Hye Ran Kim, Joong-Ki Kook, Young-Hyo Chang, Il Kwon Bae, Kwangha Lee
• Format: Article
• Language: English
• Published: Hindawi Limited 2014-01-01
• Series: BioMed Research International
• Online Access: http://dx.doi.org/10.1155/2014/250408

Introduction. The aim of this study was to differentiate between Candida famata and Candida guilliermondii correctly by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and gene sequencing. Methods. Twenty-eight Candida strains from blood cultures that had been identified as C. famata (N=25), C. famata/C. guilliermondii (N=2), and C. 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 and ITS genes and compared the results with those obtained by the VITEK 2 system. Results. All 28 isolates were finally identified as C. guilliermondii. Sequencing analysis of the 28S rRNA gene showed 99.80%–100% similarity with C. guilliermondii for all 28 strains. The ITS gene sequencing of the strains showed 98.34%–100% homology with C. guilliermondii. By MALDI-TOF, we could correctly identify 21 (75%) of 28 C. guilliermondii isolates. Conclusion. We should suspect misidentification when C. famata is 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.