Multicenter evaluation of the VITEK MS matrix-assisted laser desorption/ionization-time of flight mass spectrometry system for identification of bacteria, including Brucella, and yeasts.

The use of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry has proven to be rapid and accurate for the majority of clinical isolates. Some gaps remain concerning rare, emerging, or highly pathogenic species, showing the need to continuously expand the databases. In this multicenter study, we evaluated the accuracy of the VITEK MS v3.2 database in identifying 1172 unique isolates compared to identification by DNA sequence analysis. A total of 93.6% of the isolates were identified to species or group/complex level. A remaining 5.2% of the isolates were identified to the genus level. Forty tests gave a result of no identification (0.9%) and 12 tests (0.3%) gave a discordant identification compared to the reference identification. VITEK MS is also the first MALDI-TOF MS system that is able to delineate the four members of the Acinetobacter baumannii complex at species level without any specific protocol or special analysis method. These findings demonstrate that the VITEK MS v3.2 database is highly accurate for the identification of bacteria and fungi encountered in the clinical laboratory as well as emerging species like Candida auris and the highly pathogenic Brucella species.

Development and application of MALDI-TOF MS for identification of food spoilage fungi.

Filamentous fungi are frequently involved in food spoilage and cause important food losses and substantial economic damage. Their rapid and accurate identification is a key step to better manage food safety and quality. In recent years, MALDI-TOF MS has emerged as a powerful tool to identify microorganisms and has successfully been applied to the identification of filamentous fungi especially in the clinical context. The aim of this study was to implement a spectral database representative of food spoilage molds. To this end, after application of a standardized extraction protocol, 6477 spectra were acquired from 618 fungal strains belonging to 136 species and integrated in the VITEK MS database. The performances of this database were then evaluated by cross-validation and ∼95% of correct identification to the species level was achieved, independently of the cultivation medium and incubation time. The database was also challenged with external isolates belonging to 52 species claimed in the database and 90% were correctly identified to the species level. To our best knowledge, this is the most comprehensive database of food-relevant filamentous fungi developed to date. This study demonstrates that MALDI-TOF MS could be an alternative to conventional techniques for the rapid and reliable identification of spoilage fungi in food and industrial environments.

Routine identification of Nocardia species by MALDI-TOF mass spectrometry.

We here show adequate species identification for bacterial isolates of the genus Nocardia spp. through VITEK mass spectrometry. Application of a specific sample preparation method in combination with a robust matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) database leads to 94% accurate identification to the species level on a set of 164 isolates. The possibility to identify Nocardia spp. using MALDI-TOF MS will be available in the next release of VITEK MS update (IVD Version 3.0).