Comparison of ribotyping and arbitrarily primed PCR for molecular typing of Salmonella enterica and relationships between strains on the basis of these molecular markers

Arbitrarily primed PCR (AP-PCR) using a discriminatory 10-mer primer and an automated EcoRI ribotyping technique (Riboprinter) were compared for their ability to discriminate between 100 serovars of Salmonella, including mult iple isolates representing Salm. Enteritidis PT4 and Salm. Typhimurium DT10 4. Profiles generated by each method were subjected to numerical analysis u sing GelCompar software, resulting in the construction of phylogenetic tree s and calculation of Simpson's numerical index of diversity (DI), Both meth ods were highly discriminatory for isolates of Salmonella (Ribotype DI = 0. 990, AP-PCR DI = 0.997) with EcoRI ribotyping proving more discriminatory t han AP-PCR for isolates of Typhimurium DT104. The population structure was found to be clonal by numerical analysis of markers generated by both metho ds with serovars being polyphyletic in some cases and grouped in a single c luster in others. No absolute correlation nas observed in the relationships between strains formed on the basis of ribo- and AP-PCR markers and serolo gical characteristics.