Distribution of the Shigella sonnei insertion elements in Enterobacteriaceae

The distribution of IS1, IS600, IS629, IS630 and IS640, present in an Shigella sonnei strain, was examined in strains belonging to various species of enteric bacteria. Four Shigella species including Sh. sonnei contained all IS elements, several of which were in large numbers, and showed species-specific distribution patterns. The other strains contained some of the IS elements in a few copies or none at all, except for some clinical isolates in the Escherichia coli strains, which showed similar distribution patterns to those of the Shigella species, suggesting that the E. coli isolates are closely related to those in Shigella. The IS elements examined may be used to classify various bacterial strains and to identify the Shigella strains and some of the E. coli strains to be isolated from various sources.