title: Allele distribution and genetic diversity of VNTR loci in Salmonella enterica serotype Enteritidis isolates from different sources.
abstract: BACKGROUND
  Salmonella enterica serotype Enteritidis (S. Enteritidis) is a zoonotic pathogen, which can be found in many sources including animals and the environment. However, little is known about the molecular relatedness among S. Enteritidis isolates from different sources. We have applied multiple-locus variable number tandem repeat analysis (MLVA) to study the genetic diversity of S. Enteritidis isolates from human and non-human sources.
  
  
  RESULTS
  We identified 38 unique MLVA types using nine VNTR loci markers for discrimination between 145 S. Enteritidis isolates from different sources including humans (n = 41), chickens (n = 45), and eggs (n = 40). There were 20 distinct MLVA types identified from human isolates, 17 distinct MLVA types from chicken isolates, and 5 from egg isolates. We compared allele distribution and frequency for each VNTR marker and measured allelic polymorphism within each VNTR locus of S. Enteritidis isolates from the sources using Nei's diversity index (D). Differences in allele distribution and frequency were detected in most loci of study isolates. Different genetic diversity for certain loci was identified in isolates from different sources. The average of genetic diversity (D) was lower in egg isolates (0.16) compared to human (0.41) and chicken (0.30). However, for loci SE3, SE7, and SE9, human isolates showed significantly higher diversity than both chicken and egg isolates. Whereas for loci SE5 and SE10, chicken isolates had significantly higher diversity than both human and egg isolates. Minimum-spanning tree (MST) comprised one major cluster, a minor cluster, and four clonal expansions. MLVA application enabled a cluster analysis by the MST of the S. Enteritidis isolates by sources, which allows a great insight into the genetic relatedness and the possible flow of these organisms between different reservoirs and humans.
  
  
  CONCLUSIONS
  Differences in allele distribution and genetic diversity of VNTR loci in S. Enteritidis isolates from different sources were found. Polymorphism in most of the VNTR loci was more frequent among human S. Enteritidis isolates than isolates from chickens or eggs. Therefore, VNTR profiles of S. Enteritidis isolates from a specific source should be further evaluated as potential markers in epidemiologic investigations to trace S. Enteritidis to their probable source.
authors.affiliation: National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI, USA. chose@msu.edu
authors.forename: Seongbeom
authors.initials: S
authors.lastname: Cho
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Whittam
authors.forename: David J
authors.initials: DJ
authors.lastname: Boxrud
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Bartkus
authors.forename: A Mahdi
authors.initials: AM
authors.lastname: Saeed
mesh_terms: D000483:Alleles; D000818:Animals; D001434:Bacteriophage Typing; D002417:Cattle; D002642:Chick Embryo; D002645:Chickens / Q000382:microbiology; D003670:Deer; D004285:Dogs; D005516:Food Microbiology; D014644:Genetic Variation; D006801:Humans; D008322:Mammals / Q000382:microbiology; D051379:Mice; D018598:Minisatellite Repeats; D010802:Phylogeny; D012480:Salmonella Infections / Q000382:microbiology*; D012477:Salmonella enteritidis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D046070:Sea Lions
references.citation: J Clin Microbiol. 2004 Dec;42(12):5722-30
references.pmid: 15583305
references.citation: Epidemiol Infect. 1995 Apr;114(2):227-36
references.pmid: 7705486
references.citation: Avian Dis. 2001 Oct-Dec;45(4):875-86
references.pmid: 11785892
references.citation: J Clin Microbiol. 2006 Nov;44(11):3849-54
references.pmid: 16943354
references.citation: FEMS Microbiol Lett. 2007 Oct;275(1):16-23
references.pmid: 17692097
references.citation: J Clin Microbiol. 2007 Sep;45(9):3058-61
references.pmid: 17609320
references.citation: J Appl Microbiol. 2007 Sep;103(3):565-72
references.pmid: 17714389
references.citation: Poult Sci. 1994 Jan;73(1):89-98
references.pmid: 8165173
references.citation: Infect Immun. 2003 Dec;71(12):6734-41
references.pmid: 14638758
references.citation: Emerg Infect Dis. 1999 Sep-Oct;5(5):607-25
references.pmid: 10511517
references.citation: J Infect Dis. 1993 Jan;167(1):107-11
references.pmid: 8418156
references.citation: J AOAC Int. 2006 Mar-Apr;89(2):504-11
references.pmid: 16640300
references.citation: Clin Infect Dis. 2004 Apr 15;38 Suppl 3:S244-52
references.pmid: 15095196
references.citation: J Clin Microbiol. 2001 Jan;39(1):154-61
references.pmid: 11136764
references.citation: Infect Immun. 1996 Dec;64(12):5015-21
references.pmid: 8945540
references.citation: BMC Microbiol. 2004 Jun 08;4:22
references.pmid: 15186506
references.citation: Epidemiol Infect. 1990 Aug;105(1):21-7
references.pmid: 2200698
references.citation: J Clin Microbiol. 2003 Apr;41(4):1469-79
references.pmid: 12682132
references.citation: Environ Microbiol. 2007 Apr;9(4):1047-59
references.pmid: 17359275
references.citation: Nucleic Acids Res. 1999 Jan 15;27(2):573-80
references.pmid: 9862982
references.citation: J Appl Microbiol. 2002;92(2):196-209
references.pmid: 11849346
references.citation: J Clin Microbiol. 2007 Feb;45(2):536-43
references.pmid: 17151203
references.citation: Epidemiol Infect. 1987 Oct;99(2):291-4
references.pmid: 3315705
references.citation: Nature. 1993 Sep 16;365(6443):274-6
references.pmid: 8371783
references.citation: Microbes Infect. 2001 Mar;3(3):237-47
references.pmid: 11358718
references.citation: Microbiol Mol Biol Rev. 1998 Jun;62(2):275-93
references.pmid: 9618442
references.citation: J Bacteriol. 2005 Sep;187(18):6545-55
references.pmid: 16159788