to optochin when incubated in an atmosphere with elevated CO2 but is susceptible when incubated in ambient air. Bile solubility is a more specific test for S. pseudopneumoniae than optochin susceptibility, as the organism is not bile soluble (1). S. sanguinis group The genetically heterogeneous S. sanguinis group was formerly known as S. sanguinis. Some taxonomists have lumped the S. sanguinis group in with the S. mitis group based on 16S rRNA gene sequence analysis, but S. sanguinis group organisms exhibit divergent phenotypic characteristics. Isolates in the S. sanguinis group are arginine and esculin positive. Like members of the S. mitis group, they are negative for acetoin production and mannitol and sorbitol fermentation. The S. sanguinis group includes S. sanguinis, S. parasanguinis, and S. gordonii (14). S. salivarius group The S. salivarius group is closely related to the S. bovis group. Species from this group that have been isolated from human infection include S. salivarius and S. vestibularis, as well as S. thermophilus, which has been identified from dairy products. S. salivarius group organisms are positive for acetoin production and are esculin positive but are negative for arginine hydrolysis and fermentation of mannitol and sorbitol. S. mutans group Members of the S. mutans group are primarily isolated from the human oral cavity and includes several species that are phenotypically similar. S. mutans and S. sobrinus are the species within this group most commonly isolated from human infection. They do not hydrolyze arginine but are positive for acetoin production, esculin hydrolysis, and mannitol and sorbitol fermentation. Automated biochemical methods for identification For the VGS, the use of automated systems for identification has historically been reported as problematic, and this theme applies to multiple automated methodologies. One of the major factors affecting the quality of the identifications generated is that the systems may not have all species represented in their databases (32). In one investigation comparing the accuracy of the Vitek2 ID-GPC card to that of conventional agar-based biochemical methods for identification of a variety of Gram-positive and Gram-negative organisms, 72% of Gram-positive isolates were accurately identified by the Vitek2 system (21). Among the most problematic identifications (whether incorrectly identified or unresolved) were the VGS; S. anginosus, S. mutans, and S. sanguinis were misidentified as other VGS species and, in some instances, as S. pneumoniae (21). An investigation into the ability of the BD Phoenix system SMIC/ID panel to identify Streptococcus spp.