MALDI-TOF MS experience with the identification of complex microorganisms using two devices in a National Reference Laboratory.

Unlabelled: Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) methodology has meant a true revolution in clinical microbiology, optimizing diagnosis times through reliable results in a matter of minutes, replacing phenotypic and molecular procedures in several cases. Today, two major platforms are commercially available, the MALDI Biotyper (Bruker Daltonics Inc., Bremen, Germany) and the VITEKMS PRIME (bioMérieux, Marcy l'Etoile, France). In Argentina, the pioneering adoption of this technology took place at the National Reference Laboratory of the National Institute of Infectious Diseases, then a strategic network has emerged to disseminate the experience to all clinical laboratories utilizing MALDI-TOF and oversee their operational efficacy. In this study, we developed a strictly in parallel comparative evaluation of the performance of the Microflex LT and the next generation VITEK MS PRIME for the identification of a large number of complex microorganisms with clinical relevance, based on updated platforms and databases. The overall agreement of correct identifications of both systems was 98.23%, with the same or better resolution as rRNA gene sequencing but with cheaper and faster. Each has its advantages and limitations, so it will be up to each individual laboratory to evaluate which one is most appropriate for its workflow. Once purchased, both platforms represent enormous cost savings in supplies and labor in any laboratory.

Importance: This work detailed a matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) experience with the identification of a large set of complex microorganisms using two devices in the settings of a National Reference Laboratory. In Argentina, we coordinate the national network of mass spectrometry (MS), an extended work group formed in year 2015 that includes all public and private laboratories that have incorporated the technology as a diagnostic tool through the different commercial platforms available on the market. At this time, as a National Reference Laboratory, we conducted this comprehensive assessment of MALDI-TOF MS performance for the identification of diverse bacteria, specifically targeting pathogens of significant public health concern. During investigation, we identified certain limitations inherent to the methodology and the results obtained have considerable impact that must be transferred to the users of MS platforms in clinical laboratories all over the world.