Generally, molecular approaches proposed for the identification of staphylococci can be divided into those based on the detection of species-specific sequences and those based on the detection of sequence variations in ubiquitous elements such as rRNA and tRNA operons or chaperonin-encoding genes (3). To the best of our knowledge, species-specific primers have been published only for S. sciuri (of all the staphylococci in the S. sciuri group) (7). All the strains were tested by PCR using species-specific primers for S. sciuri based on previously published primers and methods (7). Bright bands indicating a positive reaction were obtained for all 23 S. sciuri strains (Table (Table1)1) and agreed with the identification by API Staph and ID32 STAPH. However, the fact that strong or weak hybridization signals were obtained for all S. lentus and S. vitulinus strains suggests that this set of primers may not be reliable in the identification of S. sciuri. PCR amplification of the 16S-23S rRNA intergenic spacer region was performed in accordance with the protocols previously described by Couto et al. (4) and Shittu et al. (16). This PCR method enabled identification of all isolates to the species or subspecies level. Out of the 28 isolates, 8 strains were identified as S. sciuri subsp. sciuri, 15 were identified as S. sciuri subsp. rodentium, 3 were identified as S. lentus, and 2 were identified as S. vitulinus by the 16S-23S rRNA PCR method.
In conclusion, our study showed that the members of the S. sciuri group can be identified and differentiated from other staphylococci from human clinical samples on the basis of the oxidase test. Only the recently described Staphylococcus fleurettii is also novobiocin resistant, coagulase negative, and oxidase positive as well (24). It should be noted that this bacterium has not been isolated from clinical samples of humans. However, certain problems could arise in the identification of these bacteria to the species level by use of API Staph and ID32 STAPH, since S. vitulinus is not included in the database for these tests.