Comparison of MALDI-ToF MS with the RapidecCarba NP test for the detection of carbapenemase-producingEnterobacteriaceae

Abstract Although carbapenemase-producingEnterobacteriaceae (CPE) have become a serious publichealth issue, their detection remains challenging. The aimof this study was to implement a test based on imipenemhydrolysis by matrix-assisted laser desorption/ionizationtime-of-flight mass spectrometry (MALDI-ToF MS), using65 strains producing or not a carbapenemase. Then, we comparedits performance to that of the Rapidec Carba NP testusing 20 additional strains. The MS-based test effectivelydiscriminated between CPE and other non-carbapenemsusceptiblestrains compared to the Rapidec Carba NP test(sensitivity 100% and 92%, specificity 94% and 92%, respectively).The MS-based test gave less difficulty in interpretationthan the colorimetric Rapidec Carba NP test.MALDI-ToF gave a result in less than one hour and limitedthe use of expensive molecular assays. In conclusion, thehydrolysis test based on MALDI-ToF MS can detect clinicallyrelevant CPE isolates in routine practice. This technology,also described to screen for carbapenem resistance inPseudomonas aeruginosa and Acinetobacter baumanniicomplex strains, also seems to be interesting in routine practicefor these pathogens