摘要
Background:Carbapenemase-producing Klebsiella pneumoniae(CP-Kp)poses distinct clinical challenges due to extensively drug resistant(XDR)phenotype,and sequence type(ST)11 is the most dominant blaKPC-2-bearing CP-Kp clone in China.The purpose of this current retrospective study was to explore the genetic factors associated with the success of XDR CP-Kp ST11 strains circulated in the intensive care unit(ICU)of a Chinese tertiary hospital.Methods:Six ST11 XDR CP-Kp strains were identified between May and December 2014 and validated by minimum inhibitory concentration examination,polymerase chain reaction,and pyrosequencing.The six ST11 XDR CP-Kp,as well as three multi-drug resistant(MDR)and four susceptible strains,were sequenced using single-molecule real-time method.Comprehensively structural and functional analysis based on comparative genomics was performed to identify genomic characteristics of the XDR ST11 CP-Kp strains.Results:We found that ST11 XDR blaKPC-2-bearing CP-Kp strains isolated from inpatients spread in the ICU of the hospital.Functionally,genes associated with information storage and processing of the ST11 XDR CP-Kp strains were more abundant than those of MDR and susceptible strains,especially genes correlative with mobile genetic elements(MGEs)such as transposons and prophages.Structurally,eleven large-scale genetic regions taken for the unique genome in these ST11 XDR CP-Kp strains were identified as MGEs including transposons,integrons,prophages,genomic islands,and integrative and conjugative elements.Three of them were located on plasmids and eight on chromosomes;five of them were with antimicrobial resistance genes and eight with adaptation associated genes.Notably,a new blaKPC-2-bearingΔΔTn1721-blaKPC-2 transposon,probably transposed and truncated fromΔTn1721-blaKPC-2 by IS903D and ISKpn8,was identified in all six ST11 XDR CP-Kp strains.Conclusion:Our findings suggested that together with clonal spread,MGEs identified uniquely in the ST11 XDR CP-Kp strains might contribute to their formidable adaptability,which facilitated their widespread dissemination in hospital.
基金
the Chinese Ministry of Science and Technology(No.2016YFC0903800)
the National Natural Science Foundation of China(No.81870010)
the Natural Science Foundation of Beijing Municipality(No.7192217)。
