Identification of the novel class D β-lactamase OXA-679 involved in carbapenem resistance in Acinetobacter calcoaceticus. (7th March 2019)

• Record Type: Journal Article
• Authors: Tietgen, Manuela; Kramer, Jan S; Brunst, Steffen; Djahanschiri, Bardya; Wohra, Sonali; Higgins, Paul G; Weidensdorfer, Marko; Riedel-Christ, Sara; Pos, Klaas M; Gonzaga, Aitor; Steglich, Matthias; Nübel, Ulrich; Ebersberger, Ingo; Proschak, Ewgenij; Göttig, Stephan
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 74:Number 6(2019)
• Page Start: 1494
• Page End: 1502
• Publication Date: 2019-03-07
• Subjects: Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dkz080
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Objectives: The aim of this study was to characterize the Acinetobacter calcoaceticus clinical isolate AC_2117 with the novel carbapenem-hydrolysing class D β-lactamase (CHDL) OXA-679. Methods: Identification of the species and β-lactamases was verified by genome sequencing (PacBio) and phylogenetic analyses. Antibiotic susceptibility of AC_2117 and transformants harbouring cloned bla OXA-679 was evaluated using antibiotic gradient strips and microbroth dilution. OXA-679 was purified heterologously and kinetic parameters were determined using spectrometry or isothermal titration calorimetry. The impact of OXA-679 production during imipenem therapy was evaluated in the Galleria mellonella infection model. Results: Sequencing of the complete genome of the clinical A. calcoaceticus isolate AC_2117 identified a novel CHDL, termed OXA-679. This enzyme shared sequence similarity of 71% to each of the families OXA-143 and OXA-24/40. Phylogenetic analyses revealed that OXA-679 represents a member of a new OXA family. Cloning and expression of bla OXA-679 as well as measurement of kinetic parameters revealed the effective hydrolysis of carbapenems which resulted in reduced susceptibility to carbapenems in Escherichia coli and A. calcoaceticus, and high-level carbapenem resistance in Acinetobacter baumannii . Infection of larvae of G. mellonella with a sublethal dose of bla OXA-679 -expressing A. baumannii could not be cured by high-dose imipenem therapy, indicating carbapenem resistance in vivo . Conclusions: We identified bla OXA-679 in a clinical A. calcoaceticus isolate that represents a member of the new OXA-679 family and that conferred high-level carbapenem resistance in vitro and in vivo .