Background:Group A Streptococcus (GAS) cause a wide range of human infections. Typing of emm gene can be used to predict tropism and virulence potential. Recently, a more virulent emm1/ST28 lineage (M1UK) emerged in Europe. Likewise, PAHO/WHO reported an increase of invasive GAS (iGAS) in South America, with detection of M1UK in Uruguay and Argentina.
Methods: Here we characterized five iGAS isolates obtained between 2023 and 2024, in Brazil. Strains were identified using MALDI-TOF and WGS was performed using Illumina.
Results: Three iGAS strains (60%) belonged to emm1/ST28, one (20%) to emm94/ST89 and one (20%) to emm44/ST1516. emm1/ST28 strains were detected in three different hospitals, and patients were between 5 and 74 years old. emm94/ST89 was resistant to erythromycin, clindamycin and tetracycline and carried ermA and tetM genes, while emm44/ST1516 was resistant to tetracycline carrying tetM gene. emm1/ST28 strains did not harbor any AMR genes; however, they had more virulence genes when compared to other strains. Genes coding for FCT region (fctA, fctb, lepA and srtC1), as well as SIC protein and pyrogenic exotoxin SpeA were exclusively identified in emm1/ST28. Phylogenetic analysis including reference GAS genomes from other countries clustered our emm1/ST28 strains in a separate group, which was closer to M1 global lineage when compared to M1UK.
Discussion: Our results suggest the emergence of emm1/ST28 among iGAS in Brazil, pointing to the rise of a new regional M1 clone with potential to spread rapidly in the country. Maintaining epidemiological surveillance is necessary to evaluate this hypothesis.