2026 Volume 79 Issue 4 Pages 150-161
We aimed to specify the characteristics of group A Streptococcus M1 (n = 23) or non-M1 (n = 282) isolates from adult (n = 176) and pediatric (n = 129) populations in central Japan, October 2024–April 2025. Of the 14 speA-possessing non-M1 isolates, there were seven emm3.93 isolates from 6 non-invasive samples of pediatric patients and 1 invasive specimen of an adult patient. We found the distribution of M1 clones containing M1global (n = 1), M113snps (n = 4), or M1UK (n = 18) lineages in the central Japan region consisting of Tokyo, Chiba, Tochigi, Saitama and Kanagawa. The M1 clones were from 21 non-invasive samples of pediatric/adult patients and 2 invasive specimens from adult patients. Additionally, we determined the sic nucleotide alleles and observed the M1global/M113snps/M1UK sic clustering. Of the CovS amino acid (AA) mutations among M1, there was an insertion of transposase (ISAs1-like IS1548 transposase, 377 AA) into the CovS histidine kinase-like ATPase domain (following AA position 458) of one invasive M1UK isolate. Our observations suggest that CovS AA mutations in invasive isolates with M1UK should be specified within the four functional domains of CovS to evaluate their hypervirulent properties.
