Analysis of BLACHDL genes and insertion sequences related to carbapenem resistance in acinetobacter baumannii clinical strains isolated in Warsaw, Poland

Alicja Słoczyńska, Matthew E. Wand, Stefan Tyski, Agnieszka E. Laudy*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Acinetobacter baumannii is an important cause of nosocomial infections worldwide. The elucidation of the carbapenem resistance mechanisms of hospital strains is necessary for the effective treatment and prevention of resistance gene transmission. The main mechanism of carbapenem resistance in A. baumannii is carbapenemases, whose expressions are affected by the presence of insertion sequences (ISs) upstream of blaCHDL genes. In this study, 61 imipenem-nonsusceptible A. bauman-nii isolates were characterized using phenotypic (drug-susceptibility profile using CarbaAcineto NP) and molecular methods. Pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) methods were utilized for the genotyping. The majority of isolates (59/61) carried one of the following acquired blaCHDL genes: blaOXA-24-like (39/59), ISAba1-blaOXA-23-like (14/59) or ISAba3-blaOXA-58-like (6/59). Whole genome sequence analysis of 15 selected isolates identified the following intrinsic blaOXA-66 (OXA-51-like; n = 15) and acquired class D β-lactamases (CHDLs): ISAba1-blaOXA-23 (OXA-23-like; n = 7), ISAba3-blaOXA-58-ISAba3 (OXA-58-like; n = 2) and blaOXA-72 (OXA-24-like; n = 6). The isolates were classified into 21 pulsotypes using PFGE, and the representa-tive 15 isolates were found to belong to sequence type ST2 of the Pasteur MLST scheme from the global IC2 clone. The Oxford MLST scheme revealed the diversity among these studied isolates, and identified five sequence types (ST195, ST208, ST208/ST1806, ST348 and ST425). CHDL-type carbapenemases and insertion elements upstream of the blaCHDL genes were found to be widespread among Polish A. baumannii clinical isolates, and this contributed to their carbapenem resistance.

Original languageEnglish
Article number2486
Pages (from-to)1-14
Number of pages14
JournalInternational Journal of Molecular Sciences
Issue number5
Publication statusPublished - 1 Mar 2021

Bibliographical note

Funding Information:
This study was partially supported by grants from the Medical University of Warsaw (grants no. FW15/PM2/16 and FW15/PM1/18) and by the Foundation for the Development of Diag-nostics and Therapy, Warsaw, Poland (REGON: 006220910, NIP: 5262173856 and KRS: 0000195643).

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • CHDL enzymes
  • CarbAcineto NP test
  • Carbapenem resistance
  • Insertion sequences
  • MLST
  • Multidrug resistance
  • PFGE


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