Molecular epidemiological characteristics of carbapenem-resistant Pseudomonas aeruginosa clinical isolates in southeast Shanxi, China

Objectives: Infection by carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a serious clinical problem worldwide. However, the molecular epidemiology of the clinical isolates varies depending on the region. This study was conducted to analyse the resistance phenotype and clarify the genetic and epidemiological properties of CRPA clinical isolates from southeast Shanxi, China. Methods: Fifty-seven isolates of CRPA were collected from a hospital in this region. These isolates were reidentified by MALDI-TOF and subjected to whole-genome sequencing by next-generation sequencing. Phylogenetic trees were constructed based on single nucleotide polymorphisms (SNPs), after which multilocus sequence typing (MLST) was performed and antimicrobial resistance genes were identified. Results: All the 57 CRPA isolates carried at least one kind of gene encoding carbapenemase, such as blaIMP-1, blaIMP-10, blaOXA-10, blaOXA-395, blaOXA-396, blaOXA-485, blaOXA-486, blaOXA-488, blaOXA-494, and blaOXA-50. The isolates harboured AIM-1, CMY-51, mecD, and NmcR genes and carried one kind of Pseudomonas-derived cephalosporinase (PDC) β-lactamase-encoding gene, such as blaPCD-1 to blaPCD-3, blaPCD-5, or blaPCD-7 to blaPCD-10. Two isolates were found to harbour the aminoglycoside-modifying enzyme genes aadA1 and aadA7; however, no isolates were found to harbour genes encoding 16S rRNA methylase or quinolone resistance-related genes. These CRPA isolates belonged to various sequence types (STs), two of which, namely, ST235 and ST277, were high-risk types. Conclusions: Our findings indicate that CRPA isolates carrying resistance genes with unique regional characteristics are spreading in this region, with a high diversity of STs, especially in high-risk clones. These findings highlight the necessity for further measures to prevent CRPA spread in Shanxi.