Phenotypic and molecular characterizations of carbapenem-resistant Acinetobacter baumannii isolates collected within the EURECA study

Multi-drug-resistant Acinetobacter baumannii isolates are key pathogens that contribute to the global burden of antimicrobial resistance. This study aimed to investigate the phenotypic and molecular character-istics of carbapenem-resistant A. baumannii (CRAB) isolates from the EURECA clinical trial. In total, 228 CRAB clinical strains were recovered from 29 sites in 10 European countries participating in the EURECA study between May 2016 and November 2018. All strains were reconfirmed centrally for identification and antimicrobial susceptibility testing, and were then subjected to DNA isolation and whole-genome sequencing (WGS), with analysis performed using BacPipe v.1.2.6. K and O typing was performed using KAPTIVE. Overall, 226 (99.1%) strains were confirmed as CRAB isolates. The minimum inhibitory con-centration (MIC90) results of imipenem and meropenem were > 16 mg/L. WGS showed that the isolates mainly harboured bla(OXA-23) (n = 153, 67.7%) or blaOXA-72 (n = 70, 30.1%). Four bla(OXA-72) isolates from Serbia co-harboured bla(NDM-1). An IS5 transposase family element, ISAba31, was found upstream of the blaOXA-72 gene harboured on a small (similar to 10-kb) pSE41030-EUR plasmid. The majority of isolates (n = 178, 79.1%) be-longed to international clone II. Strains belonging to the same sequence type but isolated in different countries or within the same country could be delineated in different clusters by core-genome multi-locus sequence typing (MLST). Whole-genome/core-genome MLST showed high diversity among the iso-lates, and the most common sequence type was ST2 (n = 153, 67.7%). The EURECA A. baumannii strain collection represents a unique, diverse repository of carbapenem-resistant isolates that adds to the exist-ing knowledge of A. baumannii epidemiology and resistance genes harboured by these strains. (C) 2021 The Author(s). Published by Elsevier Ltd.

Automated summary

This study investigated the phenotypic and molecular characteristics of carbapenem-resistant Acinetobacter baumannii isolates from the EURECA clinical trial. The isolates mainly harbored bla(OXA-23) or blaOXA-72 genes, with the majority belonging to international clone II and showing high diversity.