Genomic and patient epidemiology of Streptococcus dysgalactiae subspecies equisimilis in Houston, Texas

Our study provides considerable new information about the genomic epidemiology and patient characteristics of Streptococcus dysgalactiae subspecies equisimilis (SDSE) infections in a large metropolitan area in the United States. We discovered that all abundantly occurring genetic lineages were comprised of isolates with multiple emm gene types and multilocus sequence types. Analyses based solely or predominantly on these two commonly employed molecular epidemiologic markers obscure a detailed understanding of SDSE genetic diversity, population genomics, and may fail to reveal important disease associations. Our work highlights the need for longitudinal SDSE whole-genome sequencing-based surveillance and analysis of this emerging human pathogen. Such efforts will contribute to enhanced epidemiologic understanding and patient demographics and may aid improved diagnostics, infection control, public health strategies, and vaccine development for a pathogen that disproportionately affects older patients and patients with underlying medical conditions. These at-risk populations are currently rapidly expanding in the United States and many other high-income countries.