Streptococcus taoyuanensis sp. nov., a Novel Species Isolated from a Patient with Bacteremia.

ABSTRACT

Streptococcus spp. are important opportunistic pathogen of bacteremia in both immunocompetent and immunosuppressed patients. A streptococcal strain, designated ST2T, was isolated from the blood specimen of a bacteremic patient. Comparative analyses of 16S rRNA, rpoB and groEL gene sequences demonstrated that the novel strain ST2T is a member of the genus Streptococcus. Based on of 16S rRNA gene sequence similarities, the type strains of Streptococcus (S.) parasanguinis (99.2%), S. ilei (98.8%), S. oralis subsp. oralis (97.6%), S. australis (97.5%) and S. sanguinis (97.5%) were the closest neighbours to strain ST2T. The housekeeping gene sequences (rpoB and groEL) similarities of strain ST2T to these closely related type strains were 80.4-97.4%, respectively. The complete draft genome of strain ST2T consisted of 2,155,906 bp with a G + C content of 42.0%. Strain ST2T has an average nucleotide identity (ANI) value of 94.1 and 81.3% with S. parasanguinis ATCC 15912T and S. ilei I-G2T, respectively. The highest in silico DNA-DNA hybridization value with respect to the closest species S. parasanguinis was 55.6%, below the species cut-off of 70% hybridization. The primary cellular fatty acids of strain ST2T were C160, C181 ω9c, C180 and C140. Based on biochemical criteria and molecular genetic evidence, it is proposed that strain ST2T be assigned to a new species of the genus Streptococcus as Streptococcus taoyuanensis sp. nov. The type strain of Streptococcus taoyuanensis is ST2T (=NBRC 115928T = BCRC 81374T) as the type strain.