Genomic insights into blaAFM-positive carbapenem-resistant Pseudomonas aeruginosa in China

Carbapenem-resistant <i>Pseudomonas aeruginosa</i> (CRPA) poses a global threat; however, the epidemiological characteristics and clinical significance of <i>bla</i> _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 <i>bla</i> _AFM-positive CRPA were elucidated. We characterised the genetic features of <i>bla</i> _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 <i>bla</i> _AFM-positive multidrug-resistant (MDR) strain, PA19-3158 (ST1123), was identified, with the <i>bla</i> _AFM-1 gene located on a novel 518,222 bp megaplasmid. Additionally, big data analysis revealed the genomic characteristics of <i>bla</i> _AFM-positive CRPA across China. A total of three different <i>bla</i> _AFM gene variants were identified among these isolates, namely <i>bla</i> _AFM-1 (44.12%), <i>bla</i> _AFM-2 (52.94%), and <i>bla</i> _AFM-4 (2.94%). Our findings identified ST463 as the dominant clone among <i>bla</i> _AFM-positive CRPA in different regions of China, with some <i>bla</i> _AFM-positive CRPA isolates from these regions exhibiting high genetic similarity. Notably, all <i>bla</i> _AFM-positive CRPA isolates carried multiple antibiotic resistance genes (ARGs), with approximately 38% co-harboring the carbapenem-resistant gene <i>bla</i> _KPC-2 and approximately 47% co-harboring the tigecycline-resistant gene <i>tmexCD-toprJ</i>. Correlation analysis underscored the significant role of mobile genetic elements in facilitating <i>bla</i> _AFM gene transfer. These results highlight the critical need for continuous surveillance of <i>bla</i> _AFM-positive CRPA in clinical settings to mitigate potential risks.