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Genetic characteristics: A clonal group of serovar Weltevreden isolated in farmed shrimp from Vietnam’s Mekong Delta showed susceptibility to most tested antimicrobials, though some isolates exhibited resistance to florfenicol, chloramphenicol, sulfamethoxazole, or trimethoprim. 

All sequenced serovar Weltevreden isolates in a Danish study belonged to ST365 and carried key virulence genes located within Salmonella Pathogenicity Islands 1–5. Ten isolates possessed the IncFII(S) plasmid, similar to the virulence-associated plasmid pSPCV found in S. Paratyphi C, while one isolate contained an IncQ1 plasmid co-located with resistance genes (strA/B, sul2, tetA), similar to the IncQ1-type plasmid pNUC in S. Typhimurium. Pangenome analysis identified 7,891 genes, with a core genome of 4,892 genes, showing highly similar accessory genomes between clinical and environmental isolates. Additionally, serovar Weltevreden featured unique genomic regions containing glpX (class II fructose-1,6-bisphosphatase), rfbC (dTDP-4-dehydrorhamnose 3,5-epimerase), and cmtB (mannitol-specific PTS enzyme IIA component), which are involved in carbohydrate biosynthesis pathways.

Animal reservoir: Wild geckos are likely to be the reservoir for serovar Weltevreden. Serovar Weltevreden was also frequently reported from seafood. 

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