Rapid, sensitive and specific detection of OXA-48-like-producing Enterobacteriaceae by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The emergence of Enterobacteriaceae producing the class D carbapenemase OXA-48 has become a public health concern, particularly in southern Europe and in the Mediterranean area. The existing MALDI-TOF MS assays that detect carbapenemase activity have disregarded the Enterobacteriaceae producing OXA-48-like enzymes. Here, we assessed the ability of an optimized MALDI-TOF MS imipenem hydrolysis assay to detect OXA-48-like-producing Enterobacteriaceae. We tested 372 non duplicate isolates of Enterobacteriaceae from 9 species, among which 92 harbored a blaOXA-48-like gene and 180 were non-susceptible to ertapenem. The vast majority (98.9%) of the OXA-48-like producers were detected and 97.8% of the ertapenem non-susceptible isolates were correctly classified. From the agar plate to the final result, the turnaround time of the test was 90min. This quick, easy and accurate MALDI-TOF MS test can expedite the implementation of hygiene measures to prevent dissemination of OXA-48-like-producing Enterobacteriaceae and limit outbreaks.