Genomic characterization of a multidrug-resistant Salmonella enterica serovar Goldcoast sequence type 358 strain in China.

OBJECTIVES

Salmonella enterica serovar Goldcoast has been identified as the agent responsible for multistate epidemic outbreaks in humans. However, knowledge regarding the antimicrobial resistance and transmission of S. Goldcoast is scarce. This study aimed to investigate the genomic features of a multidrug-resistant S. Goldcoast sequence type 358 strain in China.

METHODS

Antimicrobial susceptibility of S. enterica strain SalGC_ZJ_53 was determined by microdilution broth assay. Whole genomic DNA was extracted and sequenced using the Illumina NovaSeq platform. De novo genome assembly was performed using Unicycler and the draft genome was annotated using the NCBI Prokaryotic Genome Annotation Pipeline. The sequence type (ST), antimicrobial resistance genes and Salmonella pathogenicity islands were identified from the genome sequence. The core genome multilocus sequence typing (cgMLST) analysis between S. enterica SalGC_ZJ_53 and all of the S. Goldcoast strains retrieved from the public database was performed using BacWGSTdb server.

RESULTS

Salmonella enterica SalGC_ZJ_53 was resistant to ampicillin, amikacin, cefotetan, cefazolin, ciprofloxacin, gentamicin and tetracycline. The genome size was calculated as 4,904,788 bp, with 4595 protein-coding sequences and GC content of 52.0%. This isolate was assigned to ST358. Several antimicrobial resistance genes and salmonella pathogenicity islands, as well as multiple insertion sequences were identified. The closest relative of S. enterica SalGC_ZJ_53 was another isolate recovered from the UK, differing by only six cgMLST loci.

CONCLUSIONS

This study reports the first genome sequence of a multidrug-resistant S. Goldcoast isolate in China. These data may help to understand the antimicrobial resistance mechanisms and transmission dynamics of this rare serovar of Salmonella infection in humans.