Characterization of the Chromosomally Located Metallo--Lactamase Genes and in a Carbapenem-Resistant Clinical Isolate.

Characterization of the multidrug resistance (MDR) region in strain PA59 revealed the presence of antibiotic resistance genes, including and , within a complex genetic landscape of mobile genetic elements. Carbapenem-resistant (CRPA) strains were isolated from Shanghai Changhai Hospital. Polymerase chain reaction (PCR) was used to detect the -lactamase genes in the isolated strains. Strains carrying two or more genes were subjected to whole-genome sequencing (WGS) and in-depth bioinformatics analysis. A total of 94 CRPA strains were isolated, among which PA59 was determined to carry and genes. Compared with single-gene positive or other and dual-gene positive strains reported, PA59 exhibited a broader range of drug resistance. We discovered a multidrug resistant (MDR)-related region composed of various mobile elements in the PA59 chromosome. This region carried many resistance genes, including the target genes and . By further comparing the mobile elements GI13 and Ph08, we speculated that this integron structure carrying and was initially integrated into the genomic island or prophage, forming a more complex genetic structure, and then further integrated into the PA59 chromosome through plasmids. Phylogenetic tree analysis showed limited sequence similarity between PA59 and other CRPA strains. This study identified PA59 as the first reported strain carrying both and on the chromosome. The assembly and annotation of the PA59 genome provide valuable insights into the genomic diversity and gene content of this clinically important pathogen, aiding the development of effective strategies against antibiotic resistance.