Decadal Evolution of KPC-related plasmids in Pseudomonas aeruginosa high-risk clone ST463 in Zhejiang, China.

Klebsiella pneumoniae carbapenemase-producing Pseudomonas aeruginosa (KPC-PA) isolates have quickly expanded in China, especially the high-risk clone ST463. We aimed to explore the evolution of KPC-related plasmids driving ST463 clone success. Whole-genome sequencing of 1258 clinical P. aeruginosa strains (2011-2020) identified 106 ST463-PA isolates, with a KPC prevalence of 90.6%. Early on (2011-2012), ST463-PA obtained the KPC-encoding type II (pT2-KPC) or type I plasmid (pT1-KPC) to overcome carbapenem stress. Between 2012 and 2017, pT1-KPC plasmid dominated due to its lower fitness costs and IS26-driven bla amplification ability. By 2017-2020, large fragment deletions in pT1-KPC formed pT1-KPC plasmid. It conferred even lower fitness costs, enhanced bla gene stability, and greater copy-number flexibility, while maintaining horizontal transmission ability. Consequently, pT1-KPC plasmid finally succeeded, making ST463 the dominant ST in China. Our findings highlight evolutionary pressures driving ST463 dominance and emphasize the need for targeted strategies to control its spread and antibiotic resistance development.