Comparison between the Biflex III-Biotyper and the Axima-SARAMIS Systems for Yeast Identification by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Abstract

). Species were identified by using routine conventional phenotypical methods and internal transcribed spacer (ITS) sequencing in case of discrepancy. We used expanded thresholds for species identification (log score of >1.7 with 3 identical consecutive propositions and no discrepancy between the duplicates for the Bruker Daltonics system and similitude of >40% with 5 successive identical propositions and no discrepancy between the duplicates for the Shimadzu system). Of the 312 isolates, 272 (87.2%) and 258 (82.7%) were successfully identified by the Bruker Daltonics and Shimadzu systems, respectively. All isolates were successfully identified within the most frequent and clinically relevant Candida species by the two systems. Nonvalid results corresponded mainly to species not or poorly represented in the databases. Major misidentifications were observed for 2 isolates (0.6%) by the Bruker Daltonics system and 4 isolates (1.3%) by the Shimadzu system. In conclusion, the performances of the Bruker Daltonics and the Shimadzu systems for yeast identification were good and comparable under routine clinical conditions, despite their differences in sample preparation, database content, and spectrum analysis.

Advantages of Using Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry as a Rapid Diagnostic Tool for Identification of Yeasts and Mycobacteria in the Clinical Microbiological Laboratory

“…The use of matrixassisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of clinical yeast and mycobacterial isolates has been evaluated in some studies (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). However, there has been a limited number of direct comparison studies focusing on the performance of the two MALDI-TOF systems to rapidly identify yeast and mycobacterial clinical isolates (26)(27)(28).…”

Evaluation of Intact Cell Matrix-Assisted Laser Desorption/Ionization Timeof- Flight Mass Spectrometry for Capillary Electrophoresis Detection of Controlled Bacterial Clumping

“…Four commercial systems are mainly used in routine identification of microorganism, namely: BioTyper, SARAMIS, VITEK MS and Andromas, provided by Bruker, Shimadzu, bioMérieux and Andromas SAS, respectively [14][15][16][17]. Unfortunately, the cost of the software and the required licenses are often a limiting factor for a common use of these systems.…”

“…Initially, bacterial colonies were smeared on a MALDI target as a thin layer and overlaid with 1.0 μl of matrix solution: DHB (50 mg/mL), HCCA (10 mg/mL) or SA (20 mg/mL) in a solvent mixture (EtOH/ACN/H 2 O, 1:1:1 (v/v/v) to examine the impact of the kind of a matrix on recorded spectra [16]. The TFA solution was added to solvent mixture to 0.1-2.5% v/v final concentrations.…”

“…On the other hand, in routine IC MALDI identification of microorganisms it is necessary to keep the time of bacterial cell incubation the same as in the case of reference bacteria. Otherwise, it may result in misidentification of bacterial species [1][2][3][4][5][6][7][14][15][16][17].…”

Development of Two Molecular Approaches for Differentiation of Clinically Relevant Yeast Species Closely Related to Candida guilliermondii and Candida famata

“…Molecular methods such as PCR-restriction fragment length polymorphism (RFLP), real-time PCR, Luminex techniques, electrophoretic karyotyping, and PCR with type-specific primers have been developed to distinguish some of these species, but other species were not involved in those studies (30-33). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a promising technique that works well to distinguish yeast species, although a few closely related species (such as C. fermentati) may still be misidentified (34)(35)(36). Because the internal transcribed spacer (ITS) regions (ITS1, 5.8S, and ITS2) and the D1 and D2 regions of the large ribosomal subunit were confirmed as the most useful targets for species-level identification of yeasts (37-39), these regions were sequenced for these closely related yeast species, for further RFLP analysis.…”