Coriander borne <i>Salmonella</i> superbug: genomic assessments of chromosomal and plasmid-associated resistance, virulence and MGEs of XDR <i>Salmonella</i> enterica Typhi NH1

The drug-resistant strains of <i>Salmonella</i> enterica serovar Typhi (<i>S</i>. Typhi) are serious threats to health sectors worldwide. This study focuses on genomic characterization of environmentally derived an extensively drug resistant (XDR) strain of <i>Salmonella</i> Typhi, highlighting its potential to cause significant outbreak. The XDR strain (labeled as NH1) was isolated from fresh coriander, and characterized through whole-genome sequencing to investigate its lineage diversity, niche adaptation, sources and resistant mechanism. The NH1 strain exhibits phylogenomic association with clinical lineages <i>S</i>. Typhi NCTC8385 and ASM3025476. Its genome, assembled in 67 contigs, exhibited expected coverage and GC content, harboring a mega-plasmid, virulence factors, and intrinsic and extrinsic antimicrobial resistance genes. Plasmid annotation revealed IncQ1 and IncY plasmids responsible for the acquired resistance. SPIFinder identified SPI1-10 pathogenicity islands, and the CRISPR-Cas locus, associated with bacterial defense, bile salt resistance and biofilm formation, was present. NH1 strain also possesses numerous mobile elements (proteins and transposases), 12 prophages, and secretion systems (types I-IV, VI), aiding its survival in environment like vegetables. The genomic characterization of <i>S</i>. Typhi NH1 highlights the emergence of coriander-borne XDR strain, underscoring the need for targeted prevention to mitigate its public health impact.