RT Journal Article SR Electronic(1) A1 VIEIRA, VERÔNICA V. A1 TEIXEIRA, LÚCIA M. A1 ZAHNER, VIVIANE A1 MOMEN, HOOMAN A1 FACKLAM, RICHARD R. A1 STEIGERWALT, ARNOLD G. A1 BRENNER, DON J. A1 CASTRO, ANGELA C. D.YR 1998 T1 Genetic relationships among the different phenotypes of Streptococcus dysgalactiae strains JF International Journal of Systematic and Evolutionary Microbiology, VO 48 IS 4 SP 1231 OP 1243 DO https://doi.org/10.1099/00207713-48-4-1231 PB Microbiology Society, SN 1466-5034, AB The species Streptococcus dysgalactiae was proposed to accommodate a heterogeneous group of streptococci associated with infections in animals and human beings. This taxon is now considered to include animal isolates of α-haemolytic group C streptococci, previously called S. dysgalactiae; animal and human isolates of β-haemolytic group C streptococci, previously called ‘S. equisimilis’; β-haemolytic group L strains associated with infections in animals and, rarely, in humans; and β-hiaemolytic group G strains isolated from humans. DNA-DNA reassociation experiments (hydroxyapatite method) and multilocus enzyme electrophoresis (MEE) were performed on reference strains and clinical isolates to determine the genetic relationships among these different phenotypic categories. DNA-DNA hybridization tests showed that they were related at the species level, despite the phenotypic and host heterogeneity. Both genotypic and phenotypic characterization indicated that S. dysgalactiae could be separated into two major sub-groups. The first subgroup contained α-haemolytic strains that showed levels of DNA relatedness with the type strain of S. dysgalactiae ranging from 84 to 90% and from 82 to 88% under optimal (55 °C) and stringent (70 °C) conditions, respectively. The second sub-group contained βhaemolytic strains showing levels of relatedness ranging from 71 to 79% (55 °C) and from 62 to 73% (70 °C). Percentage divergence varied from 0·5 to 1·0% (α-haemolytic group) and from 20 to 3·5% (α-haemolytic group). A dendrogram based on phenotypic similarity between the enzyme bands produced by MEE showed a Jaccard similarity coefficient of 0·45 between the subclusters formed by the two sub-groups. The results of phenotypic and genotypic characterization were consistent with a published proposal to divide S. dysgalactiae into two subspecies, S. dysgalactiae subsp. dysgalactiae and S. dysgalactiae subsp. equisimilis, with a few modifications., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/00207713-48-4-1231