title: Identification of specific gene sequences conserved in contemporary epidemic strains of Salmonella enterica.
abstract: Genetic elements specific to recent and contemporary epidemic strains of Salmonella enterica were identified using comparative genomic analysis. Two epidemic multidrug-resistant (MDR) strains, MDR Salmonella enterica serovar Typhimurium definitive phage type 104 (DT104) and cephalosporin-resistant MDR Salmonella enterica serovar Newport, and an epidemic pansusceptible strain, Salmonella serovar Typhimurium DT160, were subjected to Salmonella gene microarray and suppression subtractive hybridization analyses. Their genome contents were compared with those of coexisting sporadic strains matched by serotype, geographic and temporal distribution, and host species origin. These paired comparisons revealed that epidemic strains of S. enterica had specific genes and gene regions that were shared by isolates of the same subtype. Most of these gene sequences are related to mobile genetic elements, including phages, plasmids, and plasmid-like and transposable elements, and some genes may encode proteins conferring growth or survival advantages. The emergence of epidemic MDR strains may therefore be associated with the presence of fitness-associated genetic factors in addition to their antimicrobial resistance genes.
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, 402 Bustad Hall, Pullman, WA 99164-7040, USA.
authors.forename: Min-Su
authors.initials: MS
authors.lastname: Kang
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Besser
authors.forename: Dale D
authors.initials: DD
authors.lastname: Hancock
authors.forename: Steffen
authors.initials: S
authors.lastname: Porwollik
authors.forename: Michael
authors.initials: M
authors.lastname: McClelland
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Call
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000453:epidemiology / Q000382:microbiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D017124:Conserved Sequence; D004196:Disease Outbreaks / Q000662:veterinary*; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010957:Plasmids; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000382:microbiology; D019779:Salmonella enterica / Q000145:classification* / Q000187:drug effects / Q000235:genetics*; D012486:Salmonella typhimurium / Q000145:classification / Q000187:drug effects / Q000235:genetics; D017422:Sequence Analysis, DNA; D012703:Serotyping