Strangles, caused by Streptococcus equi subspecies equi (S. equi) is an infectious disease of horses with worldwide distribution, but there are limited data available regarding strain variation using whole genome sequencing among and within outbreaks in the United States (US), and how US isolates compare with S. equi isolated globally. To address this knowledge-gap, we compared the whole genomes of 54 S. equi isolates from Texas and Kentucky and those of 230 publicly available sequences of S. equi isolates collected from other countries. Our results show that despite minimal variation among isolates within an outbreak some mutations do occur among individual outbreak isolates. Some S. equi strains from the US are closely related to S. equi isolates from other countries, likely reflecting international dissemination of isolates. Collectively, these data improve our understanding of phenotypic and genotypic variation of isolates within an outbreak, and the international distribution of S. equi. We also identify a novel variant of the S. equi M-protein, and observed cases of strangles that were caused by the modified-live vaccine but that were not recognized as vaccine-associated at the time of clinical sample submission.

扼杀，造成链球菌亚种相等（马链球菌）是世界性分布的马匹的传染性疾病，但也有限制使用中，并在美国（美国）爆发之内全基因组测序关于应变变化可用的数据，以及如何美国分离株比较马链球菌全局隔离。为了解决这一知识鸿沟，我们比较了得克萨斯州和肯塔基州的54种马链球菌分离株的全基因组，以及从其他国家收集的230种公开可用的马链球菌分离株序列的全基因组。我们的结果表明，尽管暴发中的分离株之间差异很小，但个别暴发分离株之间确实发生了某些突变。一些马链球菌从美国株密切相关的马链球菌来自其他国家的分离，这可能反映了菌株的国际传播。总的来说，这些数据改善我们的暴发菌株内的表型和基因型变化的了解，以及国际分销马链球菌。我们还确定了一种新的马链球菌M蛋白变体，并观察到由改良活疫苗引起的勒死病例，但在临床样品提交时并未被认为与疫苗相关。