COMPARISON OF 3 MOLECULAR METHODS FOR TYPING AND SUBTYPING PATHOGENICYERSINIA-ENTEROCOLITICA STRAINS

The efficiency of pulsed-field get electrophoresis (PFGE), ribotyping and restriction enzyme analysis of the virulence plasmid (RE AP) for t yping and subtyping strains of Yersinia enterocolitica was compared. A ll three techniques gave concordant results, and the strains studied c ould be separated into three distinct clusters: (1) heterogeneous stra ins of biotype 1A and serotype O5 (1A/O5); (2) one 3/O3 strain and all 2/O9 strains; and (3) all 4/O3, 2/O5 and two 3/O3 strains. Within clu ster 3, the 2/O5 and 3/O3 strains were related more closely to each ot her than to the 4/O3 isolates. With ribotyping, PFGE and phage-typing, the 3/O3 isolates were subdivided into two homogeneous groups, corres ponding to strains of phage type IX(b) and strains of other phage type s, respectively. Similarly, ribotyping and PFGE subdivided the 2/O9 st rains into two conserved groups (I and II), but REAP gave a different subdivision and identified a new REAP pattern (P3). The three techniqu es confirmed the clear distinction between the heterogeneous group of non-pathogenic 1A/O5 strains and the well conserved group of pathogeni c 2/O5 strains. Additional plasmids were identified in some 3/O3 strai ns. Combined, the results indicated that REAP (with EcoRI) and ribotyp ing (with EcoRV) are valuable alternatives to bioserotype determinatio n, and PFGE is the most suitable technique for epidemiological tracing .