title: DNA microarray analysis of Salmonella serotype Typhimurium strains causing different symptoms of disease.
abstract: BACKGROUND
  Salmonella enterica subsp. enterica is one of the leading food-borne pathogens in the USA and European countries. Outcome of human Salmonella serotype Typhimurium infections ranges from mild self-limiting diarrhoea to severe diarrhoea that requires hospitalization. Increased knowledge of the mechanisms that are responsible for causing infection and especially the severity of infection is of high interest.
  
  
  RESULTS
  Strains were selected from patients with mild infections (n = 9) and patients with severe infections (n = 9) and clinical data allowed us to correct for known underlying diseases. Additionally, outbreak isolates (n = 3) were selected. Strains were analyzed on a DNA-DNA microarray for presence or absence of 281 genes covering marker groups of genes related to pathogenicity, phages, antimicrobial resistance, fimbriae, mobility, serotype and metabolism. Strains showed highly similar profiles when comparing virulence associated genes, but differences between strains were detected in the prophage marker group. The Salmonella virulence plasmid was present in 72% of the strains, but presence or absence of the virulence plasmid did not correspond to disease symptoms. A dendrogram clustered strains into four groups. Clustering confirmed DT104 as being a clonal phagetype. Clustering of the remaining strains was mainly correlated to presence or absence of the virulence plasmid and mobile elements such as transposons. Each of the four clusters in the tree represented an almost equal amount of strains causing severe or mild symptoms of infection.
  
  
  CONCLUSIONS
  We investigated clinical significance of known virulence factors of Salmonella serotype Typhimurium strains causing different disease symptoms, and conclude that the few detected differences in Salmonella serotype Typhimurium do not affect outcome of human disease.
authors.affiliation: Statens Serum Institut, Bacterial Typing, Copenhagen S, Denmark. evl@ssi.dk
authors.forename: Eva
authors.initials: E
authors.lastname: Litrup
authors.forename: Mia
authors.initials: M
authors.lastname: Torpdahl
authors.forename: Burkhard
authors.initials: B
authors.lastname: Malorny
authors.forename: Stephan
authors.initials: S
authors.lastname: Huehn
authors.forename: Morten
authors.initials: M
authors.lastname: Helms
authors.forename: Henrik
authors.initials: H
authors.lastname: Christensen
authors.forename: Eva M
authors.initials: EM
authors.lastname: Nielsen
mesh_terms: D000293:Adolescent; D000328:Adult; D001434:Bacteriophage Typing; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D010861:Fimbriae, Bacterial / Q000235:genetics; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D018598:Minisatellite Repeats; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D011446:Prospective Studies; D012480:Salmonella Infections / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D017422:Sequence Analysis, DNA; D012703:Serotyping; D012720:Severity of Illness Index; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors