Optimized method for Acinetobacter species carbapenemase detection and identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

The use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for rapid detection and identification of the enzymes responsible for carbapenem resistance in Acinetobacter spp. appears as a promising option, but it will be necessary to have a standardized protocol that facilitates routine use. Based on the results reported herein and comparisons of several previously published reports, we identified the significant peaks for imipenem detection. Optimal bacterial inoculum and incubation time were established, and results obtained with and without dipicolinic acid (DPA) and Zn(2+) allowed us to distinguish between metallo-beta-lactamases and oxacillinases.