Emergence of ST1076 as a dominant high-risk clone carrying blaKPC–2 in carbapenem-resistant Pseudomonas aeruginosa from Deqing, Zhejiang, China: a 5-year genomic epidemiology study

Background Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a major healthcare-associated pathogen with high multidrug resistance and mortality. Regional clonal spread of high-risk lineages carrying carbapenemase genes poses significant challenges for infection control. Methods We analyzed 100 non-duplicate CRPA clinical isolates collected from June 2020 to December 2024 in Deqing, Zhejiang Province, China. Antimicrobial susceptibility was determined by automated systems, and molecular characterization was performed via whole-genome sequencing, multilocus sequence typing (MLST), core-genome single nucleotide polymorphism (SNP) phylogeny, resistance and virulence gene profiling, and phylogeographic analysis. Results The observed resistance rates were 95% for imipenem and 91% for meropenem. Carbapenemase-producing isolates comprised 44% (44/100), with bla KPC –2 predominating (95.5%, 42/44). MLST identified 44 sequence types, including novel ST5216. ST1076 was the dominant clone (23%, 23/100), followed by ST463 (17%). Among ST1076 isolates, 87.0% carried bla KPC –2 . Core-genome SNP analysis revealed tight clustering of 22/23 ST1076 isolates (4–105 SNPs), suggesting possible prolonged nosocomial transmission centered in the Intensive Care Unit (ICU) since mid-2020. Phylogeographic analysis showed strong clustering with ST1076 strains from Ningbo and Hangzhou, supporting intra-provincial dissemination within Zhejiang. Virulence profiling demonstrated high prevalence of T3SS effectors ( exoT 100%, exoY 97%) and frequent oprD inactivation. Conclusion This study reveals the emergence and sustained ICU-associated transmission of bla KPC –2 -harboring ST1076 CRPA as a regionally dominant clone in Zhejiang, China, while preserving high susceptibility to ceftazidime/avibactam (CZA). Enhanced local surveillance and strict infection control measures are urgently needed to prevent further spread of this high-risk lineage.