dnaJ gene sequence-based assay for species identification and phylogenetic grouping in the genus Staphylococcus.

In the last few years, many attempts have been made to use conserved gene sequences for identification and for phylogenetic studies of Staphylococcus species. In an effort to identify a more reliable approach, a dnaJ gene sequence-based database was created. In this study, an approximately 883 bp portion of the dnaJ gene sequence from 45 staphylococcal type strains was compared with 16S rRNA and other conserved gene (hsp60, sodA and rpoB) sequences available in public databases. Nucleotide sequence comparisons revealed that the staphylococcal dnaJ gene showed higher discrimination (mean similarity 77.6 %) than the 16S rRNA (mean similarity 97.4 %), rpoB (mean similarity 86 %), hsp60 (mean similarity 82 %) and sodA (mean similarity 81.5 %) genes. Analysis of the dnaJ gene sequence from 20 Staphylococcus isolates representing two clinically important species showed <1 % sequence divergence. Phylogenetic data obtained from the dnaJ gene sequence were in general agreement with those of 16S rRNA gene sequence analysis and DNA-DNA reassociation studies. In conclusion, the dnaJ gene sequence-based assay is an effective alternative to currently used methods, including 16S rRNA gene sequencing, for identification and taxonomical analysis of Staphylococcus species.