OBJECTIVETo differentiate closely related pathogenic bacteria via phylogenetic method on the basis of gyrB gene sequences.

METHODSGyrB sequences of 19 strains of E.coli, 13 Shigella spp. 2 Aeromonas caviae, 2 Aeromonas hydrophilia,1 Aeromonas veronii were determined and combined with sequences retrieved from public databases to construct phylogenetic trees. For each sequence tested, the identification deduced from the clustering relation of sequences was compared with the phenetic identification.

RESULTSAll the tested sequences, except those of Shigella boydii and Shigella dysenteriae, were corresponded with the 5 closest sequences on the tree at the species level. While the BLAST queries returned some other bacteria organisms or undetermined entries.

CONCLUSIONPhylogenetics displays good discriminative power in bacterial sequences differentiation.