Expansion of Invasive Group A <i>Streptococcus</i> M1_UK Lineage in Active Bacterial Core Surveillance, United States, 2019‒2021

Abstract

From 2015-2018 to 2019‒2021, hypertoxigenic M1_UK lineage among invasive group A Streptococcus increased in the United States (1.7%, 21/1,230 to 11%, 65/603; p<0.001). M1_UK was observed in 9 of 10 states, concentrated in Georgia (n = 41), Tennessee (n = 13), and New York (n = 13). Genomic cluster analysis indicated recent expansions.