Genomic Characteristics of a Multidrug-Resistant ST648 Isolate Co-Carrying and Genes Recovered from a Respiratory Infection in China.

BACKGROUND

The transmission of carbapenem-resistant Enterobacterales pose a significant threat to global public health, which weakens the effectiveness of most antimicrobial agents. The aim of this study is to present the genomic characteristics of a multidrug-resistant , which contains both and genes, discovered from a respiratory infection in China.

METHODS

The antimicrobial susceptibility of isolate 488 was measured by using the broth microdilution method. The Oxford Nanopore MinION and Illumina NovaSeq 6000 platforms were applied to determine the whole-genome sequence of this isolate. De novo assembly of short Illumina reads and long MinION reads were performed by Unicycler. In silico multilocus sequence typing (MLST), antimicrobial resistance genes and plasmid replicon types were determined using the genome sequencing data. Additionally, a pairwise core genome single nucleotide polymorphism (cgSNP) comparison between 488 and all ST648 strains retrieved from NCBI GenBank database were conducted using the BacWGSTdb 2.0 server.

RESULTS

488 was resistant to aztreonam, levofloxacin, cefepime, fosfomycin, amikacin, imipenem, cefotaxime, and meropenem. The complete genome sequence of 488 (belong to ST648) is made up of eleven contigs totaling 5,573,915 bp, including one chromosome and ten plasmids. Eight antimicrobial resistance genes were identified, including located in a 46,161 bp IncI1-type plasmid and the gene situated in the chromosome. Other two S617-2 and R616-1 isolates, recovered from China in 2018, are the closest relatives of 488, with only 52 SNPs difference. The genome also contains at least 57 genomic islands and several IS elements.

CONCLUSION

Our study reveals the first ST648 isolate containing both and in China. These results could provide valuable insights into the genetic characteristics, antimicrobial resistance mechanisms, and transmission dynamics of carbapenem-resistant Enterobacterales in clinical settings.