Vieira V V, Teixeira L M, Zahner V, Momen H, Facklam R R, Steigerwalt A G, Brenner D J, Castro A C
Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Brazil.
Int J Syst Bacteriol. 1998 Oct;48 Pt 4:1231-43. doi: 10.1099/00207713-48-4-1231.
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 alpha-haemolytic group C streptococci, previously called S. dysgalactiae; animal and human isolates of beta-haemolytic group C streptococci, previously called 'S. equisimilis'; beta-haemolytic group L strains associated with infections in animals and, rarely, in humans; and beta-haemolytic 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 sub-group contained alpha-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 degrees C) and stringent (70 degrees C) conditions, respectively. The second sub-group contained beta-haemolytic strains showing levels of relatedness ranging from 71 to 79% (55 degrees C) and from 62 to 73% (70 degrees C). Percentage divergence varied from 0.5 to 1.0% (alpha-haemolytic group) and from 2.0 to 3.5% (beta-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.
提出了嗜热栖热放线菌这一物种，以容纳与动物和人类感染相关的一组异质性链球菌。现在认为这个分类单元包括以前称为嗜热栖热放线菌的α-溶血C群链球菌的动物分离株；以前称为“似马链球菌”的β-溶血C群链球菌的动物和人类分离株；与动物感染相关且很少与人类感染相关的β-溶血L群菌株；以及从人类分离出的β-溶血G群菌株。对参考菌株和临床分离株进行了DNA-DNA重结合实验（羟基磷灰石法）和多位点酶电泳（MEE），以确定这些不同表型类别的遗传关系。DNA-DNA杂交试验表明，尽管存在表型和宿主异质性，但它们在物种水平上是相关的。基因型和表型特征均表明，嗜热栖热放线菌可分为两个主要亚群。第一个亚群包含α-溶血菌株，在最佳（55℃）和严格（70℃）条件下，其与嗜热栖热放线菌模式菌株的DNA相关性水平分别为84%至90%和82%至88%。第二个亚群包含β-溶血菌株，其相关性水平为71%至79%（55℃）和62%至73%（70℃）。百分比差异在0.5%至1.0%（α-溶血群）和2.0%至3.5%（β-溶血群）之间。基于MEE产生的酶带之间表型相似性的树状图显示，两个亚群形成的子簇之间的杰卡德相似系数为0.45。表型和基因型特征的结果与已发表的将嗜热栖热放线菌分为两个亚种，即嗜热栖热放线菌亚种嗜热栖热放线菌和嗜热栖热放线菌亚种似马链球菌的提议一致，但有一些修改。
