Karl Dichtl (Graz / AT), Isabel Klugherz (Graz / AT), Hanna Greimel (Graz / AT), Josefa Luxner (Graz / AT), Julian Köberl (Graz / AT), Simone Friedl (Graz / AT), Ivo Steinmetz (Graz / AT), Eva Leitner (Graz / AT)
Background: Matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS) has revolutionized diagnostics in bacteriology. To date, virtually all MALDI-TOF MS based diagnostics is carried out using systems of only two manufacturers, i.e., Bruker Daltonics (MALDI biotyper system) and bioMérieux (VITEK MS system). Recently, a new competitor (Zybio) launched the novel EXS2600 MALDI-TOF MS device. This study aimed to evaluate the performance of the three test systems by comparing the results to 16S rRNA gene sequencing.
Methods: A set of 356 previously collected difficult-to-identify bacterial isolates was tested in parallel with the three systems relying only on the direct smear method and simple formic acid extraction.
Results: MALDI Biotyper, EXS2600, and Vitek MS yielded valid results for 98.6 %, 94.4 %, and 93.3 % of all isolates, respectively. Of all valid results, agreement with sequencing data was achieved in 98.9 % (MALDI Biotyper), 98.5 % (EXS2600), and 99.7 % (Vitek MS). Misidentification rates were 0 %, 2.6 %, and 1.1 % for MALDI Biotyper, EXS2600, and Vitek MS, respectively, when only the isolates with valid measurements at single species level were considered. Minor differences concerning the handling were observed between the respective devices and software systems.
Conclusion: The three systems provided comparable results. Our data demonstrate that all systems are suitable for the use in medical diagnostic laboratories.