Phylogenetic analysis and identification of Shigella spp. by molecular probes.

Oligonucleotide probes were used for identification of Shigella and analysis of the relationship between Shigella spp. and Escherichia coli. Probe-based PCRs shown cross-reactions from Shigella to E. coli. Probe-based 16S rRNA sequencing and phylogenetic analysis showed the four species of Shigella: Sh. dysenteriae, Sh. boydii, Sh. sonnei, and Sh. flexneri, formed a cluster with E. coli. Shigella flexneri and Sh. sonnei are even more similar to E. coli than to the other two Shigella species. These results confirmed an earlier recommendation that the four species of Shigella and E. coli should be classified as five sub-groups within a single species.