Phenotypic and genotypic characterization of clinical carbapenem-resistant species harboring the metallo-beta-lactamases IMP-8 or NDM-1 in China.

UNLABELLED

Carbapenem-resistant spp. pose a significant challenge in clinical settings due to limited treatment options for nosocomial infections. Carbapenem-hydrolyzing class D beta-lactamases are the primary cause for carbapenem resistance, while metallo-beta-lactamases (MBLs) New Delhi metallo beta-lactamase (NDM) and imipenemase (IMP) also contribute. This study investigated five MBL-producing spp. strains isolated from a clinic in China in 2010. The -carrying A1014 was the first identified CRAB among all known ST150 isolates worldwide. Through whole-genome sequencing and the southern blot analysis, we determined that was located on a pR4WN-type plasmid and was located on four distinct pSU1904NDM-type plasmids. The gene was identified within a class 1 integron organized as a 5'-conserved segment (), variable region (-), and 3'-conserved segment (Δ1/). All available sequences of variants in from the NCBI were investigated and classified into five types of class 1 integrons. All plasmids were transferable, and the genes were in a conservative region. Additionally, multiple resistance genes, including those conferring resistance to aminoglycosides, tetracyclines, and macrolides, were detected on plasmids from these strains. All strains were resistant to meropenem and imipenem, while they were all susceptible to tigecycline and intermediate to polymyxin. A207 and A1014 were susceptible to cefiderocol, and only -carrying A1014 had low MIC value (4/2 µg/mL) toward cefoperazone/sulbactam. In conclusion, we characterized the phenotypic and genotypic features of one IMP-8-producing and four NDM-1-producing plasmids recovered from spp. strains isolated in 2010, contributing to the understanding of the dissemination and evolution of these enzymes.

IMPORTANCE

Given the low prevalence of IMP among and the limited sequencing technology in earlier years, research on in is scarce, and genetic information on -producing spp. strains isolated in earlier years is limited. This study revisited five MBL-carrying spp. strains isolated in 2010, characterizing their phenotypic and genotypic features. This retrospective analysis serves as a form of "bacterial archaeology," providing evidence of the evolutionary changes in genetic elements conferring antibiotic resistance.