Application of tRNA intergenic spacer PCR for identification of Enterococcus species

Abstract

tRNA intergenic spacer PCR (tDNA-PCR) was evaluated for its usefulness in the differentiation of enterococcal species of human and animal origin. This technique was carried out for 124 strains belonging to 17 enterococcal species and generated DNA fragments, which were separated by capillary electrophoresis. tDNA-PCR enabled us to discriminate for all species tested. Enterococcus faecium showed minor but reproducible differences with Enterococcus durans, while Enterococcus hirae was easily distinguishable. Enterococcus avium, Enterococcus malodoratus, and Enterococcus raffinosus generated highly similar though distinctive patterns.

FIG. 1

tDNA-PCR fingerprint patterns of enterococcal strains. a, E. faecalis 266/5371; b, E. faecium LMG 11423; c, E. hirae LMG 6399^T; d, E. durans LMG 13604; e, E. avium LMG 107444^T; f, E. malodoratus LMG 12300; g, E. raffinosus LMG 12888^T; h, E. raffinosus LMG 14595; i, E. gallinarum LMG 16204; j, E. casseliflavus LMG 10745; k, E. flavescens LMG 13518; l, E. cecorum LMG 11744; m, E. columbae LMG 11740^T. The x axis represents the fragment length in base pairs; the y axis represents the peak intensity.

FIG. 2

Dendrogram obtained from tDNA-PCR fingerprints after similarity calculation with the in-house software and clustering with UPGMA using Neighbor software. Bar, distance of 10%.