Loading...
Scarlet fever has increased in England since 2014 (NEJM JW Infect Dis Feb 2018 and Lancet Infect Dis 2018; 18:180), as have invasive infections caused by Streptococcus pyogenes. To assess pathogenic changes in S. pyogenes isolates around this time, investigators analyzed genomes of noninvasive S. pyogenes isolates from northwest London and invasive isolates taken from across England and Wales from 2009 through 2016. The investigators focused on emm, the gene encoding the serotype-defining M antigen.
The percentage of emm1 streptococcal isolates increased over time in northwest London, from 5% in 2014 to 19% in 2015 and 33% in 2016. In 2016, emm1 was the single most common genotype causing respiratory infections. Nationally, the percentage of…