Abstract Background Molecular epidemiological surveillance of carbapenem-resistant Klebsiella pneumoniae (CRKP) in neonates remains limited. This study aimed to investigate the molecular characteristics and transmission patterns of CRKP isolates from neonates. Methods A total of 120 nonduplicate CRKP isolates were consecutively collected between 2018 and 2024 from neonates at West China Second University Hospital, a tertiary-care teaching hospital and national regional medical center for children in Southwest China. The isolates were obtained from routine clinical specimens and targeted surveillance samples. Antimicrobial susceptibility testing was performed using broth microdilution or disk diffusion methods. Whole-genome sequencing was performed for genomic analysis, including sequence types (STs), capsular typing, and resistance/virulence genes. Phylogenetic analyses based on core single-nucleotide polymorphisms were performed. Results High resistance rates ( 95%) to ceftazidime-avibactam and imipenem-relebactam were observed, while susceptibility to cefiderocol, tigecycline, colistin, and aminoglycosides remained high. blaNDM (95.8%, 115/120) was the most prevalent carbapenemase gene. The major STs were ST789 (45.0%, 54/120) and ST35 (39.2%, 47/120); however, since 2024, ST35 has surpassed ST789 to become the most common ST. Notable differences between ST789 and ST35 were identified: ST789 exhibited a higher aztreonam resistance rate (96.3% vs 14.9%), while ST35 harbored virulence genes kfuABC and mce. Phylogenetic analyses suggested clonal transmission of both STs within the hospital. Conclusions This study suggests clonal dissemination of CRKP in neonates and documents a shift in the predominant ST from ST789 to ST35. ST35 strains displayed distinct resistance phenotypes and siderophore-linked virulence genes. Given that CRKP represented 73 of 310 (23.5%) neonatal K. pneumoniae isolates during 2018–2024, these data underscore the need for sustained surveillance and strengthened infection control measures in neonatal care units.
Liang et al. (Tue,) studied this question.