A Novel Shiga Toxin 1a-Converting Bacteriophage of Shigella sonnei With Close Relationship to Shiga Toxin 2-Converting Pages of Escherichia coli

In recent studies, strains of non-dysenteriae 1 Shigella (NDS) expressing Shiga toxin have been reported. In this study, we report a novel stx1a-converting bacteriophage of Shigella sonnei associated with travel to Mexico. Phylogenetic comparison between this and other stx-converting phages suggests that toxigenic NDS strains have arisen through separate horizontal transfer events from toxigenic Escherichia coli.