Comparison of genotyping methods by application to Salmonella livingstone strains associated with an outbreak of human salmonellosis

J. Eriksson, Charlotta Löfström, A. Aspan, A. Gunnarsson, I. Karlsson, E. Borch, B. de Jong, P. Radstrom

Research output: Contribution to journalJournal articleResearchpeer-review


During 2000 and 2001, an outbreak of human salmonellosis occurred in Sweden and Norway, caused by Salmonella livingstone. In this study, the genotypic differences between three strains obtained from food sources during the outbreak, two human strains and 27 more or less unrelated strains were analysed, using the three methods; automated ribotyping, pulsed field get electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD). Each method was evaluated regarding its discriminatory ability, reproducibility and typeability. Simpson's discriminatory index calculated for each method was 0.556 for automated ribotyping, 0.766 for PFGE and 0.236 for RAPD. The reproducibility, defined as the minimum similarity between individual replicates in a cluster analysis, was 96% for automated ribotyping and PFGE, and 90% for RAPD. All the strains were typeable with each method. When combining results for the three genotyping methods, it was found that RAPD did not increase the discriminatory index and was therefore excluded from further analysis. Using a combination of the results obtained from ribotyping and PFGE (D = 0.855), two strains that had been isolated from feed factories during 1998 were shown to be identical to the outbreak strain, indicating a possible route of contamination due to a clone of Salmonella livingstone persisting in feed producing facilities. No connection to poultry was established. (c) 2005 Elsevier B.V. All rights reserved.
Original languageEnglish
JournalInternational Journal of Food Microbiology
Issue number1
Pages (from-to)93-103
Number of pages11
Publication statusPublished - 2005
Externally publishedYes


  • Animal Feed
  • Animals
  • Cluster Analysis
  • Disease Outbreaks
  • Electrophoresis, Gel, Pulsed-Field
  • Food Contamination
  • Genotype
  • Humans
  • Norway
  • Random Amplified Polymorphic DNA Technique
  • Reproducibility of Results
  • Ribotyping
  • Salmonella
  • Salmonella Food Poisoning
  • Sensitivity and Specificity
  • Sweden
  • animal food
  • article
  • bacterial strain
  • bacterium contamination
  • bacterium identification
  • bacterium isolation
  • clone
  • cluster analysis
  • epidemic
  • food
  • food contamination
  • genotype
  • human
  • intermethod comparison
  • nonhuman
  • poultry
  • pulsed field gel electrophoresis
  • random amplified polymorphic DNA
  • reproducibility
  • ribotyping
  • salmonellosis
  • strain difference
  • Animalia
  • Animal feed
  • Automated ribotyping
  • Genotyping
  • Pulsed field gel electrophoresis
  • Randomly amplified polymorphic DNA
  • Reproducibility
  • FOOD
  • RAPD
  • PCR
  • animal feed
  • automated ribotyping
  • genotyping
  • randomly amplified polymorphic DNA
  • Norway Europe Palearctic region
  • Sweden Europe Palearctic region
  • salmonellosis bacterial disease diagnosis
  • Facultatively Anaerobic Gram-Negative Rods Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Enterobacteriaceae [06702] Salmonella genus pathogen strain-livingstone
  • Primates Mammalia Vertebrata Chordata Animalia (Animals, Chordates, Humans, Mammals, Primates, Vertebrates) - Hominidae [86215] human common host
  • Vertebrata Chordata Animalia (Animals, Birds, Chordates, Nonhuman Vertebrates, Vertebrates) - Aves [85500] poultry common
  • 03502, Genetics - General
  • 03506, Genetics - Animal
  • 03508, Genetics - Human
  • 10062, Biochemistry studies - Nucleic acids, purines and pyrimidines
  • 12504, Pathology - Diagnostic
  • 31000, Physiology and biochemistry of bacteria
  • 31500, Genetics of bacteria and viruses
  • 36002, Medical and clinical microbiology - Bacteriology
  • Biochemistry and Molecular Biophysics
  • genotyping laboratory techniques, genetic techniques
  • pulsed field gel electrophoresis PFGE electrophoretic techniques, laboratory techniques
  • randomly amplified polymorphic DNA laboratory techniques, genetic techniques
  • ribotyping laboratory techniques, genetic techniques
  • Infection
  • Molecular Genetics
  • PFGE
  • Hygiene and toxicology
  • Microbiological aspects


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