Disruption of the blaOXA-51-like gene by ISAba16 and activation of the blaOXA-58 gene leading to carbapenem resistance in Acinetobacter baumannii Ab244

Lopes, Bruno S, Evans, Benjamin A and Amyes, Sebastian G B (2012) Disruption of the blaOXA-51-like gene by ISAba16 and activation of the blaOXA-58 gene leading to carbapenem resistance in Acinetobacter baumannii Ab244. Journal of Antimicrobial Chemotherapy, 67 (1). pp. 59-63. ISSN 0305-7453

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Abstract

Objectives: This study examines the mechanism of carbapenem resistance in Acinetobacter baumannii isolate Ab244.  Methods: A multiplex PCR for the detection of the blaOXA-23-like, blaOXA-40-like, blaOXA-51-like and blaOXA-58-like families was performed. MICs of imipenem and meropenem were determined by the agar dilution method. The sequence surrounding the blaOXA-132 gene was determined by amplification with primer pairs encompassing a part of fxsA and an acetyltransferase gene (GNAT). The sequence upstream of the blaOXA-58 gene was determined by sequencing. SDS–PAGE and carO PCR were performed to check the integrity of the outer membrane proteins. RT–PCRs for the expression of the blaOXA-132 gene and the blaOXA-58 gene were performed.  Results: Isolate Ab244 harboured blaOXA-132 belonging to the blaOXA-51-like gene cluster and a blaOXA-58 gene. The 4239 bp region between fxsA and GNAT showed an insert of ISAba16 (where IS stands for insertion sequence) after the first 15 nucleotides of the blaOXA-132 gene, with an 8 bp target site duplication at the 5′ and 3′ ends of ISAba16. The sequence oriented in the 5′→3′ direction caused insertional inactivation of the blaOXA-132 gene. The blaOXA-58 gene was highly expressed by the promoters provided by an ISAba3-like structure found upstream of the gene. The isolate was resistant to meropenem and had intermediate resistance to imipenem, and was also positive for ISAba1.  Conclusions: This is the first report showing ISAba16-mediated inactivation of the blaOXA-132 gene in strain Ab244. The resistance to carbapenems in strain Ab244 is related to the acquisition of the blaOXA-58 gene, here governed by an ISAba3-like element.

Item Type: Article
Uncontrolled Keywords: a. baumannii,insertion sequences,β-lactamases,gene environment
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Pure Connector
Date Deposited: 24 Sep 2016 00:09
Last Modified: 22 Apr 2020 01:35
URI: https://ueaeprints.uea.ac.uk/id/eprint/59866
DOI: 10.1093/jac/dkr415

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