Genomic Insights into the First Emergence of bla_NDM-5-Carrying Carbapenem-Resistant Salmonella enterica Serovar London Strain in China

Abstract

Carbapenem-resistant Salmonella enterica (S. enterica) pose a significant threat to public health, causing gastroenteritis and invasive infections. We report the first emergence of a carbapenem-resistant S. enterica serovar London strain, A132, carrying the bla_NDM-5 gene in China. Whole-genome sequencing and bioinformatics analysis assigned A132 to be ST155, a multidrug-resistant clone frequently reported in China. The strain A132 exhibited resistance to multiple antibiotics, with 20 acquired antibiotic resistance genes (ARGs) identified, predominantly located on the IncFIB plasmid (pA132-1-NDM). Notably, the bla_NDM-5 gene was located within an IS26 flanked-class 1 integron-ISCR1 complex, comprising two genetic cassettes. One cassette is the class 1 integron, which may facilitate the transmission of the entire complex, while the other is the bla_NDM-5-containing ISCR1-IS26-flanked cassette, carrying multiple other ARGs. Genbank database search based on the bla_NDM-5-carrying cassette identified a similar genetic context found in transmissible IncFIA plasmids from Escherichia coli (p91) and Enterobacter hormaechei (p388) with a shared host range, suggesting the potential for cross-species transmission of bla_NDM-5. To our knowledge, this is the first reported case of Salmonella serovar London ST155 harboring bla_NDM-5 gene. Phylogenetic analysis indicated a close relationship between A132 and eight S. London ST155 strains isolated from the same province. However, A132 differed by carrying the bla_NDM-5 gene and four unique ARGs. Given the high transmissibility of the F-type plasmid harboring bla_NDM-5 and 18 other ARGs, it is imperative to implement vigilant surveillance and adopt appropriate infection control measures to mitigate the threat to public health.

Keywords:

• blaNDM-5
• Salmonella London
• ST155
• carbapenem resistance
• IncFIB
• integron

Data Sharing Statement

The datasets presented in this study can be found in online repositories. The genome sequence of the strain has been deposited in the NCBI database under BioProject accession number PRJNA1057448.

Ethics Approval and Informed Consent

The authors certify that the patient consent form has been obtained. Written informed consent was obtained from the patient for publication of this Case report and any accompanying images. The studies involving human participants were reviewed and approved by the Ethics Committee of the First People’s Hospital of Huzhou.

Disclosure

The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

The study was supported by grants from the public welfare technology application research program of Huzhou (Grant no. 2023GYB19), Zhejiang Province Medical and Health Technology Plan Project (Project ID: 2024KY424), and Zhejiang Provincial Natural Science Foundation of China (Grant No. LTGD24C010001).