The use of PCR ribotyping for typing strains of Listeria spp.

The potential of PCR ribotyping for discriminating between and within various species of Listeria, as well as strains of Listeria monocytogenes was examined. In total, 49 strains of Listeria monocytogenes and 12 isolates of Listeria spp. were analyzed. The genomic DNA isolated from these strains was subjected to PCR amplification in the regions between 16S and 5S rRNA. Amplifications were performed with both low and high concentrations of Taq polymerase. Length polymorphisms in the amplified DNA products enabled distinction between various strains of Listeria spp. and between various serotypes of L. monocytogenes. Six composite profiles for serotype 4b strains, 8 for 1/2a strains and 11 for 1/2b strains, were observed. In addition, several different PCR ribotyping strategies were evaluated. Restriction fragment length polymorphisms of the spacer region between the 16S and 23S rRNA genes of 16 strains of L. monocytogenes were not observed, except for two isolates. PCR ribotyping analysis displayed promise as an alternative to traditional L. monocytogenes molecular typing methods.