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 monocytoge nes was examined. In total, 49 strains of Listeria monocytogenes and 1 2 isolates of Listeria spp, were analyzed. The genomic DNA isolated fr om these strains was subjected to PCR amplification in the regions bet ween 16S and 5S rRNA. Amplifications were performed with both low and high concentrations of Taq polymerase. Length polymorphisms in the amp lified DNA products enabled distinction between various strains of Lis teria spp. and between various serotypes of L. monocytogenes. Six comp osite profiles for serotype 4b strains, 8 for 1/2a strains and 11 for 1/2b strains, were observed. In addition, several different PCR riboty ping strategies were evaluated. Restriction fragment length polymorphi sms of the spacer region between the 16S and 23S rRNA genes of 16 stra ins of L. monocytogenes were not observed, except for two isolates. PC R ribotyping analysis displayed promise as an alternative to tradition al L. monocytogenes molecular typing methods.