Phylogenetic relationships within different Acinetobacter spp.

(11 representative clinical isolates, 16S rRNA gene sequences of 12 standard strains and rpoB gene sequences of 16 reference strains included in this study), as obtained by rooted dendrogram construction on the basis of rpoB gene sequences (a) and 16S rRNA gene sequences (b). The cluster analysis was performed using the MEGA 5.2 software and was based on the neighbor-joining algorithm using species of the closest related genus (i.e., Psychrobacter cryohalolentis) as an outgroup, with 1,000 bootstrap replications. The bar indicates 1% and 5% sequence diversity. In the phylogenetic tree of the rpoB gene (a), the Acb complex could be divided into five branches, and the evolutionary relationships among the branches were reasonable. In the phylogenetic tree of the 16S rRNA gene (b), only the A. baumnnii branch was separated individually from the Acb complex, although it was located near the branch of A. junii.