Global phylogeography and genomic characterization of blaNDM-1-positive carbapenem-resistant Acinetobacter soli

To investigate the genomic and resistance features of a blaNDM-1-positive Acinetobacter soli isolate and assess the global distribution and genomic traits of A. soli.

We isolated a blaNDM-1-positive A. soli strain from a patient in 2023. Antimicrobial susceptibility testing was performed and whole-genome sequencing was used to investigate the genomic characteristics and resistance features of A. soli. Conjugation was performed to assess the transferability of the blaNDM-1-carrying plasmid, and plasmid stability was evaluated using serial-passaging experiments. Additionally, genomic analysis of 74 publicly available A. soli genomes was performed to explore their global distribution, resistance genes, plasmid replicons and phylogeographic relationships.

SZL7 exhibited resistance to meropenem (8 mg/L) and ceftazidime (≥64 mg/L), but remained susceptible to tigecycline, polymyxin B, fluoroquinolones, cefiderocol and cefoperazone-sulbactam. Among the 74 global genomes, blaNDM-1 was detected in 9.46% (7/74) of the isolates. The blaNDM-1 gene was located on a plasmid and was stably inherited after 10 days of serial passage. A total of 83.78% of the isolates originated from Asia, particularly China and Japan. Notably, all Chinese isolates were collected from coastal cities, with environmental samples predominating, indicating the importance of environmental monitoring in these high-risk areas.

This study presents the first global genomic analysis of A. soli, highlighting its potential as a reservoir and vector for clinically significant resistance genes, such as blaNDM-1. These findings emphasize the importance of continuous genomic surveillance and environmental monitoring within the One Health framework to mitigate emerging resistance threats.