A Side by Side Comparison of Bruker Biotyper and VITEK MS: Utility of MALDI-TOF MS Technology for Microorganism Identification in a Public Health Reference Laboratory

Abstract

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid, highly accurate, and cost-effective method for routine identification of a wide range of microorganisms. We carried out a side by side comparative evaluation of the performance of Bruker Biotyper versus VITEK MS for identification of a large and diverse collection of microorganisms. Most difficult and/or unusual microorganisms, as well as commonly encountered microorganisms were selected, including Gram-positive and negative bacteria, mycobacteria, actinomycetes, yeasts and filamentous fungi. Six hundred forty two strains representing 159 genera and 441 species from clinical specimens previously identified at the Laboratoire de santé publique du Québec (LSPQ) by reference methods were retrospectively chosen for the study. They included 254 Gram-positive bacteria, 167 Gram-negative bacteria, 109 mycobacteria and aerobic actinomycetes and 112 yeasts and moulds. MALDI-TOF MS analyses were performed on both systems according to the manufacturer’s instructions. Of the 642 strains tested, the name of the genus and / or species of 572 strains were referenced in the Bruker database while 406 were present in the VITEK MS IVD database. The Biotyper correctly identified 494 (86.4%) of the strains, while the VITEK MS correctly identified 362 (92.3%) of the strains (excluding 14 mycobacteria that were not tested). Of the 70 strains not present in the Bruker database at the species level, the Biotyper correctly identified 10 (14.3%) to the genus level and 2 (2.9%) to the complex/group level. For 52 (74.2%) strains, we obtained no identification, and an incorrect identification was given for 6 (8.6%) strains. Of the 178 strains not present in the VITEK MS IVD database at the species level (excluding 71 untested mycobacteria and actinomycetes), the VITEK MS correctly identified 12 (6.8%) of the strains each to the genus and to the complex/group level. For 97 (54.5%) strains, no identification was given and for 69 (38.7%) strains, an incorrect identification was obtained. Our study demonstrates that both systems gave a high level (above 85%) of correct identification for a wide range of microorganisms. However, VITEK MS gave more misidentification when the microorganism analysed was not present in the database, compared to Bruker Biotyper. This should be taken into account when this technology is used alone for microorganism identification in a public health laboratory, where isolates received are often difficult to identify and/or unusual microorganisms.

Comparison of Saramis 4.12 and IVD 3.0 Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Mycobacteria from Solid and Liquid Culture Media

“…Identification of mycobacteria has not reached an optimal level of routine testing yet and published studies showed discrepant performances, depending on spectrometer, extraction method, algorithm, library, media, and biomass used for the assays (15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32). In this study, we compared two distinct databases of Vitek-MS, the Saramis v4.12 open database and the new IVD v3.0 closed database.…”

“…It was initially evaluated with mycobacterial intact cells (9)(10)(11)(12), but several investigators worked on improving inactivation and protein extraction (13)(14)(15)(16)(17)(18)(19)(20). Most published studies assessed the performance of MALDI-TOF BioTyper (Bruker Daltonics, Bremen, Germany) (15,17,(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). Few of them evaluated Vitek MS (bioMérieux, Marcy l'Etoile, France) (16,17,20,24,25,32).…”

“…Most published studies assessed the performance of MALDI-TOF BioTyper (Bruker Daltonics, Bremen, Germany) (15,17,(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). Few of them evaluated Vitek MS (bioMérieux, Marcy l'Etoile, France) (16,17,20,24,25,32). Performances ranged widely, from 0% (24) to 94.4% (17) correct identifications depending on database versions, algorithms, and media (liquid or solid) used.…”

Identification of Molds by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

“…Thus, when present in their respective databases, 76.7% (33/43) and 50.0% (10/20) of isolates could be correctly identified (to both the species and genus levels) with the Bruker Biotyper and Vitek MS systems, respectively; only one misidentification was obtained (1 Fusarium proliferatum isolate misidentified as Fusarium oxysporum) with the Vitek MS system, whereas there was no misidentification with the Bruker Biotyper system. When absent from their respective databases, 12 misidentifications (mainly to the genus level) were obtained with the Vitek MS system, as opposed to none with the Bruker Biotyper system (21).…”

“…In a head-to-head comparison of the Bruker Biotyper and Vitek MS systems carried out on a large collection of microorganisms, including filamentous fungi, at a public health reference laboratory in Québec, Canada, it was found that only 17 of 71 isolates tested were referenced in both systems' databases, with 43 being present in the Bruker Biotyper database and 20 being present in the Vitek MS database (21). Thus, when present in their respective databases, 76.7% (33/43) and 50.0% (10/20) of isolates could be correctly identified (to both the species and genus levels) with the Bruker Biotyper and Vitek MS systems, respectively; only one misidentification was obtained (1 Fusarium proliferatum isolate misidentified as Fusarium oxysporum) with the Vitek MS system, whereas there was no misidentification with the Bruker Biotyper system.…”