DIVISION OF THE GENUS ENTEROCOCCUS INTO SPECIES GROUPS USING PCR-BASED MOLECULAR TYPING METHODS

Broad-range 16S rDNA PCR (BR-PCR) applied to DNA from 32 clinical ente rococcal isolates and 12 other enterococci from a clinical reference c ollection followed by species-specific hybridization analysis identifi ed 25 strains of Enterococcus faecalis and 19 Enterococcus species. Ra ndomly amplified polymorphic DNA (RAPD) analysis using UPGMA clusterin g on the same material revealed four different clusters at a similarit y level of 49 %. Based on partial 16S rDNA sequence analysis of variab le regions V4 and V9, it was possible to divide the 19 type strains sp ecifying the genus Enterococcus into 12 different 16S rDNA species gro ups. The type strain distribution then served as a template for the an alysis of the other 44 strains which were assigned to four different s pecies groups (a-d) based on their 16S rDNA motifs. There was good agr eement with the RAPD clusters. Species group a was an individual speci es line containing 25 strains that were identified as E. faecalis. Gro up b also represented an individual species line of 12 strains identif ied as E. faecium. The remaining seven strains that formed species gro ups c and d could not be fully identified to species by this analysis. It was concluded that BR-PCR of 16S rDNA followed by partial sequence analysis of the PCR products is a reliable technique for the identifi cation and classification of enterococci. Further division of unresolv ed species groups should be achievable if regions other than V4 and V9 of 16S rDNA are also analysed.