A Pandrug-Resistant Providencia Carrying Two blaIMP Carbapenemase-Encoding Genes Including blaIMP-69, a New blaIMP Variant, on a Newly Identified Worldwide-Distributed IncC Plasmid

Abstract

Imipenemase (IMP) is a metallo-β-lactamase that confers resistance to almost all β-lactams. Identification of IMP genes is essential for understanding and combatting antibiotic resistance. In this study, we report a pandrug-resistant Providencia strain from a human rectal swab. This strain carried 2 blaIMP carbapenemase genes, blaIMP-69 and blaIMP-4. IMP-69 is a novel IMP variant with an amino acid substitution at A21T compared with IMP-8. blaIMP-69 was found in a blaIMP-69-aacA4 array of an integron on a 165-kilobase (kb) IncC self-transmissible plasmid, whereas blaIMP-4 was located in a blaIMP-4-qacG-aacA4-catB3 array of an integron on a 19-kb nonself-transmissible plasmid. Such coexistence has the potential to allow the generation of new, hybrid blaIMP variants by homologous recombination. The blaIMP-69-carrying IncC plasmid belonged to the core-genome plasmid multilocus sequence typing (cgPMLST) 3.5 type. We found that cgPMLST 3.5 IncC plasmids have been circulating worldwide for decades and may represent a common vehicle mediating the spread of antimicrobial resistance.

Keywords: Providencia; carbapenemase; genome.