EFFICIENT SUBTYPING OF PATHOGENIC YERSINIA-ENTEROCOLITICA STRAINS BY PULSED-FIELD GEL-ELECTROPHORESIS

Yersinia enterocolitica is an enteropathogen that has recently and rap idly expanded over the world. There is a close correlation between the biotypes, serotypes, and phage types of the strains, making it virtua lly impossible to distinguish isolates of the same serotype with the c lassical phenotypic markers. In the present study, pulsed-filed gel el ectrophoresis (PFGE) was used to compare the NotI genomic profile (i.e ., pulsotype) of 20 strains each of serotypes 0:3, 0:9, and 0:5. Eleve n, 12 and 18 different pulsotypes were obtained, respectively, indicat ion that this technique is very efficient for subtyping pathogenic iso lates of Y. enterocolitica. Within strains of serotype 0:5, PFGE diffe rentiated two subgroups that corresponded to two biotypes (biotypes 1A and 3). Comparison of the pulsotypes of three strains of biotype 3 an d serotype 0:3 (referred to as 3/0:3) with those of strains 4/0:3 and 3/0:5 suggested that the pulsotype is close to the biotype than to the serotype. The pulsotypes of five pairs of strains isolated from the s ame patient or siblings were also analyzed. In four pairs, the two str ains displayed identical pulsotypes, indicating that PFGE might be a p owerful epidemiological tool. In the fifth pair, one restriction fragm ent differed, suggesting that genomic polymorphism may occur in vivo i n Y. enterocolitica. Finally, the in vitro genomic stabilities of one strain each of Y. enterocolitica 0:3, 0:9, and 0:5 were investigated. The pulsotypes of 10 isolated colonies were identical within each stra in, indicating that in vitro, the genome of Y. enterocolitica is much more stable than that of Y. pestis.