Emergence of clade 3 emm89 group A Streptococcus in Queensland, Australia

The emergence of a new clade of <i>emm</i>89 group A <i>Streptococcus</i> (GAS) (clade 3) has been described in several countries. Strains in this clade have been reported to have genomic characteristics that lead to increased expression of virulence factors and may confer a selective advantage over previous <i>emm</i>89 strains. To investigate whether clade 3 GAS is present in the <i>emm</i>89 GAS population of Queensland, Australia, all <i>emm</i>89 GAS isolates received by the Queensland Public Health Microbiology Reference Laboratory since <i>emm</i> typing began in the early 2000s underwent genomic sequencing and analysis. Analysis of sequences from 293 <i>emm</i>89 GAS isolates demonstrated the presence of distinct genomic groups in the Queensland <i>emm</i>89 GAS population. Unlike <i>emm</i>89 GAS populations described in the UK and USA, which were mostly ST101 and ST407, there were a relatively high number of ST142 and ST812 strains in the Queensland <i>emm</i>89 GAS population. However, the majority of Queensland isolates belonged to clade 3, with 80% (<i>n</i>=233) of <i>emm</i>89 GAS isolated from 2006 onwards belonging to this clade. All Queensland clade 3 isolates had the reported genomic features associated with higher virulence potential including increased streptolysin O production and an acapsular phenotype. Clade 3, which has emerged to become the dominant clade of <i>emm</i>89 GAS in Europe and the USA, is now also the dominant clade in Queensland.