We report 2 adult cases of invasive disease in Japan caused by Streptococcus oralis that expressed the serotype 3 pneumococcal capsule and formed mucoid colonies. Whole-genome sequencing revealed that the identical serotype 3 pneumococcal capsule locus and hyl fragment were recombined into the genomes of 2 distinct S. oralis strains.
Keywords: Japan; Streptococci; Streptococcus oralis; antimicrobial resistance; bacteria; hyl; mucoid phenotype; multifragment recombination; serotype 3 pneumococcal capsule.