Introduction. Acinetobacter baumannii is an opportunistic pathogen responsible for severe hospital-acquired infections, including bloodstream infections (BSIs). Although major epidemic clones and resistance mechanisms have been described, integrated analyses combining clinical features, patient outcomes and genomic characteristics of BSI isolates remain limited, particularly in China. Gap Statement. Comprehensive analyses integrating clinical outcomes, high-resolution genotyping, capsule locus diversity and their associations with mortality are still lacking. Aim. This study aimed to characterize the clinical characteristics and outcomes of patients with A. baumannii BSIs, as well as the phenotypic and genomic characteristics of the causative isolates. Specifically, we sought to identify high-risk clones and their association with 30-day mortality to improve diagnostic and therapeutic strategies. Methodology. A retrospective cohort study was conducted on 151 cases of A. baumannii BSIs in a tertiary hospital in China. Isolates were analysed using whole-genome sequencing to determine sequence types (STs), capsule loci and resistance and virulence gene profiles. Results. The 151 isolates were classified into 11 different STs using the Pasteur MLST scheme, with ST2 Pasteur predominating (88.1%). One isolate represented a novel Pasteur ST (ST2831 Pasteur ). Using the Oxford MLST scheme, 22 STs were identified, with ST195 Oxford , ST208 Oxford and ST540 Oxford being the most common. Four novel Oxford STs (ST2457 Oxford , ST2458 Oxford , ST2459 Oxford and ST2460 Oxford ) were identified. Twenty-three capsule locus (KL) types were detected, with KL3 being the most prevalent. Phylogenetic analysis showed clear clustering according to STs and KL types. The ST2 Pasteur lineage was characterized by the presence of the OXA-23 gene and carbapenem resistance, as well as an expanded virulence gene repertoire, suggesting enhanced pathogenic potential. The overall 30-day mortality rate was 35.1%. Patients in the death group had shorter hospital stays, fewer surgical interventions and higher rates of complications, invasive procedures and intensive care unit admission. Certain clone combinations, including ST369 Oxford -KL9, ST938 Oxford -KL210 and ST195 Oxford -KL3, were associated with higher mortality rates. Conclusion. ST369 Oxford -KL9, ST938 Oxford -KL210 and ST195 Oxford -KL3 represent high-risk clones associated with A. baumannii BSIs. Early identification of ST and capsule type, alongside clinical risk stratification, may improve diagnosis and guide treatment strategies.
Ye et al. (Tue,) studied this question.