Molecular characteristics of KPC-producing Klebsiella pneumoniae isolates from children and adults in Kunming.

UNLABELLED: The increasing prevalence of KPC-producing Klebsiella pneumoniae (KPC-Kp) poses a critical public health threat. While Sequence Type 11 (ST11) is the dominant carbapenem-resistant clone in China, the comparative molecular characteristics of isolates affecting distinct patient demographics remain understudied. Fifty non-duplicate KPC-Kp clinical isolates (18 from children, 32 from adults) were prospectively collected from four hospitals in Kunming during 2023. Whole-genome sequencing was performed to determine multilocus sequence types (MLST), capsular serotypes (KL types), plasmid replicons, and resistance/virulence gene profiles. Phylogenetic relationships were reconstructed using single-nucleotide polymorphisms and core-genome MLST. All isolates carried blaKPC-2, and 98% (49/50) belonged to ST11. Pediatric isolates were predominantly ST11-KL47 (72.2%), exhibiting a classic multidrug-resistant profile, whereas adult isolates were dominated by ST11-KL64 (59.4%) and frequently harbored IncFIB/IncH1IB virulence plasmids carrying rmpA, iuc, and iro genes, indicating a hypervirulent phenotype (CR-hvKP). Kunming isolates were genetically closely related to strains from other Chinese provinces, suggesting that local CRKP epidemiology is shaped by national dissemination of successful ST11 clones rather than isolated regional outbreaks. Although ST11 drives the regional KPC-Kp epidemic, the molecular characteristics of isolates from children and adults are distinct. The shared ST11 genetic backbone and the presence of transferable virulence plasmids in adult isolates raise a potential risk of cross-population spread. Continuous genomic surveillance is essential to monitor the possible horizontal transfer of virulence plasmids from adult to pediatric reservoirs.

IMPORTANCE: This study investigated 50 KPC-2-producing Klebsiella pneumoniae isolates from four hospitals in Kunming (2023). Nearly all (98%) belonged to ST11, confirming this clone drives the regional carbapenem-resistant epidemic. However, striking differences emerged between pediatric and adult isolates. Pediatric isolates were predominantly ST11-KL47 (72.2%) with a classic multidrug-resistant profile, whereas adult isolates were mainly ST11-KL64 (59.4%) and frequently carried IncFIB/IncH1IB virulence plasmids harboring rmpA, iuc, and iro genes, indicating a hypervirulent phenotype (CR-hvKP). Phylogenetic analysis revealed that Kunming strains are closely related to those from other Chinese provinces, suggesting national dissemination of successful ST11 clones rather than isolated local outbreaks. Although adult virulence plasmids were not found in pediatric isolates, the shared ST11 genetic backbone raises concerns about potential horizontal transfer of these plasmids from adult to pediatric populations. Continuous genomic surveillance is essential to monitor this cross‑population risk.