Abstract
Carbapenem-resistant Pseudomonas aeruginosa (CRPA) poses a global threat; however, the epidemiological characteristics and clinical significance of bla (AFM)-positive CRPA strains in China remain unclear. In this study, continuous surveillance was conducted from 2018 to 2022 in a hospital in Henan Province, China, and the genomic characteristics of bla (AFM)-positive CRPA were elucidated. We characterised the genetic features of bla (AFM)-positive CRPA isolates by antimicrobial susceptibility testing, conjugation assays, whole-genome sequencing, large-scale comparative genomics, and bioinformatic analyses. Among 628 CRPA isolates, one bla (AFM)-positive multidrug-resistant (MDR) strain, PA19-3158 (ST1123), was identified, with the bla (AFM-1) gene located on a novel 518,222 bp megaplasmid. Additionally, big data analysis revealed the genomic characteristics of bla (AFM)-positive CRPA across China. A total of three different bla (AFM) gene variants were identified among these isolates, namely bla (AFM-1) (44.12%), bla (AFM-2) (52.94%), and bla (AFM-4) (2.94%). Our findings identified ST463 as the dominant clone among bla (AFM)-positive CRPA in different regions of China, with some bla (AFM)-positive CRPA isolates from these regions exhibiting high genetic similarity. Notably, all bla (AFM)-positive CRPA isolates carried multiple antibiotic resistance genes (ARGs), with approximately 38% co-harboring the carbapenem-resistant gene bla (KPC-2) and approximately 47% co-harboring the tigecycline-resistant gene tmexCD-toprJ. Correlation analysis underscored the significant role of mobile genetic elements in facilitating bla (AFM) gene transfer. These results highlight the critical need for continuous surveillance of bla (AFM)-positive CRPA in clinical settings to mitigate potential risks.