Clinical and molecular characterizations of carbapenem-resistant Klebsiella pneumoniae among children with bloodstream infections in Beijing, China

Bloodstream infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) in children pose a significant challenge to global public health and place tremendous pressure on clinical antibiotic treatment. A longitudinal retrospective study was designed to elucidate the clinical features, antibiotic resistance phenotypes, and molecular characteristics of CRKP isolated from bloodstream infections in children. CRKP strains were collected from blood cultures over an eight-year period (2018–2025) at a tertiary children’s hospital in Beijing, China. Antimicrobial susceptibility testing and whole-genome sequencing (WGS) were performed to examine the resistance patterns and genetic diversity. CRKP bloodstream infections exhibited a distinct age-related pattern, with the highest incidence observed in infants younger than 3 months. Among the 91 isolates studied, none showed resistance to tigecycline or polymyxin B. The predominant carbapenemase genes identified were bla KPC-2 (52.7%) and bla NDM variants (40.7%), among which bla NDM-5 was the most prevalent. Strains carrying only bla KPC-2 were susceptible to ceftazidime/avibactam, whereas all strains harboring bla NDM genes demonstrated 100% resistance to this antibiotic. ST11–KL47(49.5%) was the predominant type and was strongly associated with bla KPC-2 and the 16S rRNA methyltransferase gene rmtB . Additionally, ST20–KL28 (15.4%) was prevalent and closely linked to bla NDM-5 . Although ST11–KL64 (3.3%) constituted a minor proportion of isolates, all strains within this clone harbored notable virulence genes. Pediatric CRKP bloodstream infections, predominantly affect young infants and are mediated primarily by bla KPC and bla NDM type carbapenemases. The dominant epidemic clones are ST11–KL47 and ST20–KL28, specifically linked to bla KPC-2 and bla NDM-5 , respectively. Although ST11–KL64 accounted for only a limited proportion of the isolates, the virulence genes carried by this clone merit particular concern. These findings elucidate the molecular epidemiology of CRKP in children and provide a foundation for developing effective diagnostic, therapeutic, and preventive strategies.