Genomic characterization of Salmonella enterica serovar Kentucky and London recovered from food and human salmonellosis in Zhejiang Province, China (2016–2021)

Abstract

Increasing human salmonellosis caused by Salmonella enterica serovar Kentucky and London has raised serious concerns. To better understand possible health risks, insights were provided into specific genetic traits and antimicrobial resistance of 88 representative isolates from human and food sources in Zhejiang Province, China, during 2016–2021. Phylogenomic analysis revealed consistent clustering of isolates into the respective serovar or sequence types, and identified plausible interhost transmission via distinct routes. Each serovar exhibited remarkable diversity in host range and disease-causing potential by cgMLST analyses, and approximately half (48.6%, 17/35) of the food isolates were phylogenetically indistinguishable to those of clinical isolates in the same region. S. London and S. Kentucky harbored serovar-specific virulence genes contributing to their functions in pathogenesis. The overall resistance genotypes correlated with 97.7% sensitivity and 60.2% specificity to the identified phenotypes. Resistance to ciprofloxacin, cefazolin, tetracycline, ampicillin, azithromycin, chloramphenicol, as well as multidrug resistance, was common. High-level dual resistance to ciprofloxacin and cephalosporins in S. Kentucky ST198 isolates highlights evolving threats of antibiotic resistance. These findings underscored the necessity for the development of effective strategies to mitigate the risk of food contamination by Salmonella host-restricted serovars.

Genomic analysis of Salmonella enterica from Metropolitan Manila abattoirs and markets reveals insights into circulating virulence and antimicrobial resistance genotypes

“…The London serovar has been associated with various infections in humans (Yong et al, 2005), animals, and food products (Meunsene et al, 2021). Although it is uncommonly detected and studied among Salmonella serovars, London isolates have exhibited potential zoonotic transmission and increasing resistance to antibiotics (Fang et al, 2022). In this study, London isolates were exclusively found in swine samples and only conferred resistance to limited antimicrobial classes.…”

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

“…These prevalent Chinese S. London ST155 isolates have been predominantly sourced from humans, swine, and food products, suggesting that S. London infections in humans often originate from zoonotic transmission. 49 Therefore, it is highly probable that the patient in our study had a foodborne infection. In addition, recent studies have reported a rising prevalence of S. London isolates associated with foodborne human salmonellosis in Zhejiang Province.…”

Prevalence and Antimicrobial Resistance Diversity of Salmonella Isolates in Jiaxing City, China

“…S. Kentucky sequence type (ST)198 is mostly isolated from chickens and humans [28,29]. bla CTX-M-55 , rmtB, tet(A), floR, and fosA3, together with amino acid substitution in gyrA (S83F and D83N) and parC (S80I), have contributed to the high resistance to ciprofloxacin, cephalosporin, and fluoroquinolones in S. Kentucky isolates [30][31][32]. The IncHI2 plasmid carries numerous resistance genes including bla CTX-M , aadA7, lnu(F), bla TEM-1b , rmtB, and mph(A), except for bla CTX-M-14b , which is inserted into the chromosomes of S. Kentucky isolates, enabling them to transfer vertically as intrinsic chromosomal genes within this lineage.…”