DNA-DNA reassociation was performed on 15 strains of Globicatella sanguinis to compare their taxonomic status with phenotypic characterization. All 15 strains selected for DNA-DNA reassociation readily met the criteria for species relatedness. The relative binding ratio was 81% or greater at the optimal temperature and 76% or greater at the stringent temperature, and the divergence was less than 3% for all strains hybridized with the type strain. These strains included nine strains from the Centers for Disease Control Streptococcus Laboratory culture collection that were previously included in comparative 16S rRNA gene sequencing studies as well as six additional phenotypically variant isolates. DNA-DNA relatedness was less than 18% at the optimal reassociation temperature to Aerococcus viridans, Enterococcus avium, and Streptococcus uberis, which are phenotypically similar to G. sanguinis. This study confirms these Globicatella strains were previously misidentified as S. uberis or S. uberis-like strains based on biochemical characteristics. The biochemical data from 28 strains was compiled to further define the phenotypic criteria for identification of this species. A revised description of the species should be variable reaction for pyrrolidonylarylamidase production (75% positive), positive reaction for the bile esculin test (100%), growth at 45°C (96%), variable reaction for acid production from arabinose (45% positive), and negative starch hydrolysis (0% positive). We also evaluated four rapid identification systems, the Biomerieux rapid ID32 STREP (ID32), the Crystal rapid gram-positive identification (Cry4), the BBL Crystal gram-positive identification (Cry24), and the Remel IDS RapID STR (IDS) systems for their ability to identify these strains.In the 1977 summary of the identification of viridans streptococci isolated from human sources, 7 of 1,227 isolates were reported to be Streptococcus uberis (10). It was noted at that time that these isolates phenotypically resembled Streptococcus mutans based on biochemical reactions. However, four of the seven strains grew in 6.5% NaCl broth, which differentiated this species from all other viridans streptococci. Some of these strains, identified as S. uberis, were distributed to commercial manufacturers of kits designed to identify viridans streptococci (15,16,30). These strains had phenotypic characteristics similar to those described in 1977 and were identified as S. uberis (10) until 1990. With the advent of new tests to discriminate between the genera of gram-positive cocci, it became clear that our phenotypic criteria for identification of S. uberis was probably not valid.In 1992, comparative 16S rRNA gene sequencing data for nine of these strains were analyzed to determine their phylogenetic position (4). In this study, the highest sequence homology was shown with the genus Aerococcus (91%), followed by the lactococci (88%), leuconostocs (86 to 89%), pediococci (89 to 90%), and streptococci (87 to 88%). Phylogenetic analysis showed an unknown line of desc...