Christine Uitz (Graz / AT), Karl Dichtl (Graz / AT), Josefa Luxner (Graz / AT), Simone Friedl (Graz / AT), Eva Leitner (Graz / AT), Andrea Grisold (Graz / AT), Gernot Zarfel (Graz / AT), Ivo Steinmetz (Graz / AT)
Background: Carbapenem-resistant Enterobacterales (CRE) and carbapenemase-producing Enterobacterales (CPE) pose a global healthcare threat. Rapid, reliable assays are paramount to facilitate targeted and effective therapeutic interventions. Among various diagnostic approaches, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) holds promise for carbapenemase detection, featuring advantages over molecular and phenotypic sensitivity tests. To date, only one assay is IVD labelled and commercially available. This study aims to assess and compare its performance to a novel MALDI-TOF MS-based test.
Materials & Methods: Forty pre-characterized CRE isolates (70 % CPEs) were analysed with the established IVD CE certified MALDI-TOF MS carbapenemase detection assay (MBT STAR-Carba IVD Kit; Bruker Daltonics) on the MALDI Biotyper sirius and the newly developed Carbapenemase Activity Kit for the EXS2600 MALDI-TOF MS system (Zybio), assessing performance and handling.
Results: Valid results were obtained for 93 % and 85 % isolates using the Bruker and the Zybio assay. Sensitivities, specificities, and positive and negative predictive values were 92 %, 91 %, 96 %, and 83 % for the Bruker assay and 96 %, 64 %, 85 %, and 88 % for the Zybio assay. Considerable different assay handling aspects were noted.
Conclusion: Both assays demonstrated high sensitivities, with the Bruker assay yielding fewer false positives, and were found to be suitable for the use in a routine laboratory.