Replicative transposition contributes to the evolution and dissemination of KPC-2-producing plasmid in Enterobacterales

Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales are prevalent worldwide and pose an alarming threat to public health. The incidence and transmission of bla(KPC-2) gene via horizontal gene transfer (e.g. transposition) have been well documented. However, the dynamics of transposon structure bearing bla(KPC-2) and their exact effects on the evolution and dissemination of bla(KPC-2) gene are not well characterized. Here, we collected all 161 carbapenem-resistant Enterobacterales (CRE) isolates during the early stage of CRE pandemic. We observed that the prevalence of KPC-2-producing Enterobacterales was mediated by multiple species and sequence types (STs), and that bla(KPC-2) gene was located on three diverse variants of Tn1721 in multi-drug resistance (MDR) region of plasmid. Notably, the outbreak of KPC-2-producing plasmid is correlated with the dynamics of transposon structure. Furthermore, we experimentally demonstrated that replicative transposition of Tn1721 and IS26 promotes horizontal transfer of bla(KPC-2) and the evolution of KPC-2-producing plasmid. The Tn1721 variants appearing concurrently with the peak of an epidemic (A2- and B-type) showed higher transposition frequencies and a certain superior ability to propagation. Overall, our work suggests replicative transposition contributes to the evolution and transmission of KPC-2-producing plasmid and highlights its important role in the inter- and intra-species dissemination of bla(KPC-2) gene in Enterobacterales.