Molecular epidemiological tools for Salmonella Dublin typing.

A total of 32 strains of Salmonella Dublin recovered from cattle were differentiated by electrophoretic typing of their esterases (zymotyping), restriction fragment length polymorphism of ribosomal DNA (ribotyping), arbitrarily primed PCR (AP-PCR) using five primers, PCR based on repetitive extragenic palindromic sequences (REP-PCR) and PCR based on enterobacterial repetitive intergenic consensus sequences (ERIC-PCR). ERIC-PCR and REP-PCR each gave one type, zymotyping gave three, AP-PCR gave five and ribotyping gave seven types. Combination of ribotyping and AP-PCR produced a total of 11 types, whereas 14 different types were obtained by all five methods. Thus a combination of several methods enhanced the discrimination of cattle-adapted strains among the genotypically homogeneous serovar Salmonella Dublin.