...
Relevant genetic characteristics: Whole genome sequences for 27 strains of S. Typhimurium have been deposited at GenBank as of October, 2013. Genomic characteristics of the sequenced S. Typhimurium strains include (i) a genome size ranging from 4.82- 5.09 Mb, (ii) a mol G+C% of approx. 52.2, and (iii) 4,556 to 5,619 predicted genes. Typically, Most of the strains of S. Typhimurium contain a plasmid of approx. 90 kb that carry virulence genes (Salmonella virulence plasmid (SVP)). Large resistant plasmids of approx. 200 kb , representing that represented different incompatibility types (e.g., IncHI1), have also been identified in the sequenced strains S. Typhimurium. Prophages and genomic islands are important genomic components of serovar Typhimurium; for example, S. Typhimurium str. LT2 has four prophages (Fels-1, Fels-2, Gifsy-1, and Gifsy-2). Among S. Typhimurium strains, the prophage content shows variation. Pathogenicity islands (SPIs) are found in all S. Typhimurium sequenced to date, including SPIs-1 to 6, 9, 11 to 14, and 16; being SPI-14 specific to S. Typhimurium. In addition, genomic island content shows variationsome genomic islands are strain-specific; for example, S. Typhimurium MDR strain ST1660/06 has three strain-specific genomic islands that encode putative virulence and resistance genes. Genomic islands carrying that encode antibiotic resistance appear to be a common feature of a number of S. Typhimurium MDR strains, these genomic islands include, e.g., Salmonella genomic island 1 (SGI1) described in S. Typhimurium DT104 and genomic island GI-DT12 in S. Typhimurium T000240. The latest genomic island (GI-DT12) contains antibiotic resistance genes (i.e., bla(oxa-30), aadA1, qacEΔ1, and sul1, cat, and tetA) and virulence genes (i.e., the aerobactin iron-acquisition siderophore system (lutA and lucABC), and an iron transporter (sitABCD)).
...