Identification of Uncommon Candida Species Using Commercial Identification System.

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Identification of Uncommon Candida Species Using Commercial Identification System.

J Microbiol Biotechnol. 2016 Oct 6;:

Authors: Kim TH, Kweon OJ, Kim HR, Lee MK

Abstract
Recently, several studies have revealed that commercial microbial identification systems do not accurately identify the uncommon causative species of candidiasis, including Candida famata, Meyerozyma guilliermondii, and C. auris. We investigated the accuracy of species-level identification in a collection of clinical isolates previously identified as C. famata (N=38), C. lusitaniae (N=12), and M. guilliermondii (N=5) by the Vitek 2 system. All 55 isolates were re-analyzed by the Phoenix system (Becton Dickinson Diagnostics), two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analyzers (a Vitek MS and a Bruker Biotyper), and by sequencing of internal transcribed space (ITS) regions or 26S rRNA gene D1/D2 domains. Among 38 isolates previously identified as C. famata by the Vitek 2 system, the majority (27/38 isolates, 71.1%) were identified as C. tropicalis (20 isolates) or C. albicans (7 isolates) by ITS sequencing, and none was identified as C. famata. Among 20 isolates that were identified as C. tropicalis, 17 (85%) were isolated from urine. The two isolates that were identified as C. auris by ITS sequencing originated from ear discharge. The Phoenix system did not accurately identify C. lusitaniae, C. krusei, or C. auris. The correct identification rate for 55 isolates was 92.7% (51/55 isolates) for the Vitek MS and 94.6% (52/55 isolates) for the Bruker Biotyper, as compared to results from ITS sequencing. These results suggest that C. famata is very rare in Korea, and that it should be noted the possibility of misidentification when an uncommon Candida species is identified.

PMID: 27713213 [PubMed - as supplied by publisher]