First Report of New Delhi Metallo- β -Lactamase-6 (NDM-6) in a Clinical Acinetobacter baumannii Isolate From Northern Spain.

The objective of this study was the phenotypic and genotypic characterization of a carbapenem resistant Acinetobacter baumannii (CRAB) isolate. The isolate, recovered in Northern Spain in 2019, was identified by MALDI-TOF to the species level. Antimicrobial susceptibility testing was performed using the Phoenix BD NMIC-502 Panel, E-test, and broth microdilution methods. The presence of a metallo- β -lactamase (MBL) was verified by PCR and immunochromatographic assays. The genetic location of the MBL was confirmed using S1-pulsed-field gel electrophoresis (S1-PFGE) followed by Southern blot hybridization. Whole genome sequencing (WGS) was completed using the Miseq and MinION platforms, followed by core-genome MLST (cgMLST) and seven-locus MLST analysis. The CRAB was assigned ST85 (Pasteur scheme) and ST957 (Oxford scheme) representing international clone (IC) 9 and harbored the intrinsic β -lactamase OXA-94 with IS Aba1 upstream of it, and the MBL bla _NDM-6 . Hybridization experiments revealed that the bla _NDM-6 was encoded on the chromosome. Using WGS the bla _NDM-6 environment could be identified arranged in the following order: IS Aba14 , aphA6 , IS Aba125 , bla _NDM-6 , ble _MBL , trpF , dsbC , cutA , and IS Aba14 . Downstream, a 10,462 bp duplication was identified, including a second copy of bla _NDM-6 in the following genetic composition: IS Aba125 , bla _NDM-6 , ble _MBL , trpF , dsbC , cutA , and IS Aba14 . To our knowledge, this is the first description of bla _NDM-6 in A. baumannii . The MBL was present in two copies in the chromosome in a new genetic environment associated with IS elements highlighting the contribution of mobile genetic elements in the dissemination of this gene.
(Copyright © 2020 Xanthopoulou, Urrutikoetxea-Gutiérrez, Vidal-Garcia, Diaz de Tuesta del Arco, Sánchez-Urtaza, Wille, Seifert, Higgins and Gallego.)