Identification of Candida haemulonii Complex Species: Use of ClinProTools(TM) to Overcome Limitations of the Bruker Biotyper(TM), VITEK MS(TM) IVD, and VITEK MS(TM) RUO Databases.

Rafaella C Grenfell,Gil Benard,Afonso R Da Silva Junior,Diego M Assis,João N De Almeida Júnior,Flavia Rossi,Regina B Munhoz,Viviane M F Gimenes,Adriana L Motta,Gilda M B Del Negro,Anna C Rockstroh,Luiz Juliano

doi:10.3389/fmicb.2016.00940

Abstract

Candida haemulonii is now considered a complex of two species and one variety: C. haemulonii sensu stricto, Candida duobushaemulonii and the variety C. haemulonii var. vulnera. Identification (ID) of these species is relevant for epidemiological purposes and for therapeutic management, but the different phenotypic commercial systems are unable to provide correct species ID for these emergent pathogens. Hence, we evaluated the MALDI-TOF MS performance for the ID of C. haemulonii species, analyzing isolates/strains of C. haemulonii complex species, Candida pseudohaemulonii and Candida auris by two commercial platforms, their databases and softwares. To differentiate C. haemulonii sensu sctricto from the variety vulnera, we used the ClinProToolsTM models and a single-peak analysis with the software FlexAnalysisTM. The BiotyperTM database gave 100% correct species ID for C. haemulonii sensu stricto, C. pseudohaemulonii and C. auris, with 69% of correct species ID for C. duobushaemulonii. Vitek MSTM IVD database gave 100% correct species ID for C. haemulonii sensu stricto, misidentifying all C. duobushaemulonii and C. pseudohaemulonii as C. haemulonii, being unable to identify C. auris. The Vitek MSTM RUO database needed to be upgraded with in-house SuperSpectra to discriminate C. haemulonii sensu stricto, C. duobushaemulonii, C. pseudohaemulonii, and C. auris strains/isolates. The generic algorithm model from ClinProToolsTM software showed recognition capability of 100% and cross validation of 98.02% for the discrimination of C. haemulonii sensu stricto from the variety vulnera. Single-peak analysis showed that the peaks 5670, 6878, or 13750 m/z can distinguish C. haemulonii sensu stricto from the variety vulnera.

Highlights

MATERIAL AND METHODSThe taxonomy of the pathogenic Candida species such as Candida albicans, Candida parapsilosis, and Candida glabrata has suffered significant modifications due to the description of closely related species (Turner and Butler, 2014)
For the species C. duobushaemulonii, correct species ID was achieved for seven isolates and the two CBS strains (69%), while four isolates were assigned as C. duobushaemulonii with a score between 1.797 and 1.935
All reference strains of C. pseudohaemulonii and C. auris had correct species ID with scores ≥ 2.0

Summary

Introduction

MATERIAL AND METHODSThe taxonomy of the pathogenic Candida species such as Candida albicans, Candida parapsilosis, and Candida glabrata has suffered significant modifications due to the description of closely related species (Turner and Butler, 2014). Initial evaluation using MALDI-TOF MS for the ID of C. haemulonii complex species provided promising results (Cendejas-Bueno et al, 2012), the discrimination of the variety vulnera from C. haemulonii sensu stricto was troublesome and the performance of the Vitek MSTM (bioMérieux) remains unevaluated.

Results

Conclusion