AUTHOR=Hou Xin , Xiao Meng , Chen Sharon C.-A. , Wang He , Yu Shu-Ying , Fan Xin , Kong Fanrong , Xu Ying-Chun 

TITLE=Identification and Antifungal Susceptibility Profiles of Candida nivariensis and Candida bracarensis in a Multi-Center Chinese Collection of Yeasts

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00005

DOI=10.3389/fmicb.2017.00005

ISSN=1664-302X

ABSTRACT=<p><italic>Candida nivariensis</italic> and <italic>C. bracarensis</italic> are two emerging cryptic species within the <italic>C. glabrata</italic> complex. Thirteen of these isolates from 10 hospitals in China were studied for their species identification and antifungal susceptibilities. Phenotypic and molecular [rDNA ITS sequencing, D1/D2 sequencing and ITS sequencer-based capillary gel electrophoresis (SCGE)] and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS identification methods were compared for their performance in species identification. Twelve of 13 (92.3%) isolates were identified as <italic>C. nivariensis</italic> and one as <italic>C. bracarensis</italic> using ITS sequencing as the reference method. Results obtained by D1/D2 sequencing and ITS SCGE were concordant with ITS sequencing results for all (100%) isolates. SCGE was able to subtype 12 <italic>C. nivariensis</italic> into four ITS SCGE length types. All isolates failed to be identified by the Vitek MALDI-TOF MS system (bioMérieux), whilst the Bruker MS system (Bruker Daltoniks) correctly identified all <italic>C. nivariensis</italic> isolates but using a lowered (≥1.700) cut-off score for species assignment; the <italic>C. bracarensis</italic> isolate was identified but with score &lt;1.700. The Vitek 2 Compact system could not identify 11 <italic>C. nivariensis</italic> and one <italic>C. bracarensis</italic> isolate and misidentified the remaining <italic>C. nivarensis</italic> strain as “<italic>C. glabrata.</italic>” All isolates were susceptible-dose dependent to fluconazole [minimum inhibitory concentration (MIC) range 0.5–4 μg/mL] and were classed as susceptible to echinocandins (MICs ≤ 0.06 μg/mL). All 13 isolates had low MICs for other azoles (MICs ≤ 0.5 μg/mL), amphotericin B (MICs ≤ 2 μg/mL) and 5-flucytosine (MICs ≤ 0.25 μg/mL). Our results reinforce the need for molecular differentiation of species of <italic>C. nivarensis</italic> and <italic>C. bracarensis</italic>. The performance of MALDI-TOF may be improved by adding mass spectral profiles (MSPs) into the current databases. The antifungal susceptibility profile of isolates should be monitored.</p>