Phylogenetic structure and clinical implications of carbapenemase-aerobactin (iuc) convergence in respiratory Klebsiella pneumoniae from a tertiary hospital in China, 2017–2023

OBJECTIVES: To characterise the phylogenetic structure and clinical implications of carbapenemase-aerobactin (iuc) convergence among respiratory Klebsiella pneumoniae isolates. METHODS: We performed whole-genome sequencing of 707 non-duplicate respiratory K. pneumoniae isolates collected at a tertiary hospital in China from 2017 to 2023 and linked the genomic data to blinded clinical adjudication. Isolates were grouped by carbapenemase gene carriage and iuc status. Core-genome SNP phylogenies were constructed for ST11 and ST23, and reference-plasmid mapping to pK2044 was performed in a targeted subset. Within the carbapenemase-positive subset, logistic regression was used to test the incremental contribution of iuc beyond age, Charlson Comorbidity Index, and ICU admission during hospitalisation. All-cause mortality at 14, 28, and 90 days was assessed among infection cases. RESULTS: groups showed broadly similar all-cause mortality at 14, 28, and 90 days. CONCLUSIONS: Carbapenemase-aerobactin convergence among respiratory K. pneumoniae was concentrated in dominant ST11 backgrounds and occurred in distinct lineage-specific virulence contexts. However, within the carbapenemase-positive respiratory subset, iuc added limited value for infection attribution and did not clearly separate short- to intermediate-term mortality beyond host and care-setting factors.