Co-existence ofblaKPC-2andblaVIM-2in highly carbapenem-resistantPseudomonas aeruginosaisolated in the ICU of a public hospital

Abstract

AbstractIn this study, highly carbapenem-resistantPseudomonas aeruginosa(h-CRPA) 18102011 [the minimum inhibitory concentration (MIC) value of carbapenem antimicrobial imipenem (IP) for h-CRPA is 4,096 μg/mL] was isolated from the bile of an intensive care unit (ICU) burn patient in China, and genomic sequencing revealed a complete genome. The genome’s molecular characteristics were analyzed to assess the genetic environment ofblaKPC-2andblaVIM-2. Average nucleotide identity (ANI) comparisons were used for precise species-level identification, while serotyping, multi-locus sequence typing, and the identification of acquired resistance genes, and virulence genes were also carried out. The h-CRPA 18102011 strain carryingblaKPC-2andblaVIM-2was identified as strain ST2374 and the O4 serotype. Virulence genes (plcH,exoST) and resistance genes (aph(3’)-IIb,aac(6’)-Ib-cr,ant(2’’)-Ia,blaOXA-396,blaPAO,blaKPC-2,blaVIM-2,blaPER-1,sul1,catB7,qnrVC6,fosA) were both identified in the genome. In addition, the IncpRBL16type mega-plasmid pP2011-1 carryingblaVIM-2and the IncP6 type plasmid pP2011-2 carryingblaKPC-2were identified in the strain. The genetic environment ofblaVIM-2andblaKPC-2was specifically evaluated to assess their origins.blaVIM-2was located in the region of In2075 (a novel type 1 integron) that was inserted into plasmid pP2011-1, this plasmid contained 3 novel recombination sites, as well as the typical recombination site 2 (umuC) observed for IncpRBL16type plasmids. However, the core module Tn3-ISKpn27-blaKPC-ΔISKpn6was identified as theblaKPC-2platform in plasmid pP2011-2. Conjugation experiments revealed that the plasmids pP2011-1 and pP2011-2 of the h-CRPA 18102011 strain could be transferred intoEscherichia coliwith a conjugation transfer efficiency of 10-6. TheE. colitransconjugant carriedblaKPC-2andblaVIM-2from the donor and the MIC value of IP to theE. colitransconjugant was 4,096 μg/mL, which was the same as observed for the donor. Overall, this study revealed the molecular characteristics of a VIM-2 and KPC-2-co-producing strain that was typed as O4 and ST2374. The continuous monitoring of bacteria, such as the strain investigated here, that co-harbor different types of carbapenemase genes is critical for preventing the spread of these genes.