Study on genotype of enterohemorrhagic Escherichia coli O157： H7 isolates by pulsed-field gel electrophoresis and multiple-locus variable number tandem repeat analysis

Objective To study genotype of enterohemorrhagic Escher ichia coli(EHEC)O157:H7 with differ ent subtyping methods and compare effectiveness of the methods.Methods 16 isolates of EH EC O157:H7 were analyzed by pulsed -field gel electrophor esis(PFGE)and multilocus var iable-number tandem repeat(VNT R)analysis(MLVA).Results Strains in PF GE clusters were defined by using Xba?and the confirmatory enzyme Bln?.MLVA was per for med by compar ing the number of tandem repeats at nine loci,where three loci showed no variations and six loci showed 2 to 7 variations in the 16 isolates,resulting in 14 MLVA types among the 16 isolates.While by PFGE,only 6 types were found among the 16 isolates.Conclusion The results of MLVA is highly relevant to epidemiological information.MLVA appears to have profound potential for discrimination of EHEC O157:H7 strains.isolates.Conclusion The results of MLVA is highly relevant to epidemiological information.MLVA appears to have profound potential for discrimination of EHEC O157:H7 strains.