DETERMINATION OF CLONAL RELATIONSHIPS OF SALMONELLA-TYPHIMURIUM BY NUMERICAL-ANALYSIS OF MACRORESTRICTION PROFILES

The use of numerical analysis of macrorestriction profiles resolved by pulsed-field gel electrophoresis (PFGE) for identifying epidemiologic al and clonal relationships between strains of Salmonella typhimurium was investigated. A cluster analysis based on Xba1 macrorestriction pr ofiles of 40 strains was compared to biotype, phage-type and ribotype data on each isolate to validate the integrity and significance of the results. A significant correlation between these data was noted, sugg esting that evolutionary divergence, of both recent and a more distant nature, may be detected. Moreover, two principal clonal lines of Salm . typhimurium appear to be prevalent in Denmark, of which one is compa ratively stable with respect to phenotype and genotype, while the othe r is relatively diverse in these respects. We conclude that numerical analysis of macrorestriction profiles is a useful means of evaluating interstrain relationships between Salm. typhimurium strains and has pr actical applications for both short-and long-term epidermiological sur veillance purposes.