Cell wall glycosyltransferase of <i>Streptococcus mutans</i> impacts its dissemination to murine organs

<i>Streptococcus mutans</i>, a cariogenic bacterium in humans, is associated with systemic disorders. Its cariogenic factors include glucosyltransferases (GTFs) and the glycosyltransferase rhamnose-glucose polysaccharide I (RgpI), which is involved in cell wall synthesis. However, the potential roles of these enzymes in systemic disorders remain unclear. We constructed a luciferase-tagged <i>S. mutans</i> UA159 mutant strain that lacked <i>rgpI</i> to explore the involvement of this enzyme in the systemic pathogenicity of <i>S. mutans</i>. We also employed the luciferase-tagged <i>S. mutans</i> UA159 variant, which exhibited reduced GTF production and therefore had a low glucan synthesis ability. We intravenously inoculated these luciferase-tagged mutants and parent strains into 12-week-old male BALB/c mice to evaluate their distribution to organs. Strong luminescence was noted in the spleen and kidneys, indicating that <i>S. mutans</i> was disseminated to these organs. Several organs collected from mice inoculated with the luciferase-tagged parent strain emitted a signal, and inflammatory cytokine production was detected in the blood. The luminescence intensity was lower in the kidneys of mice challenged with the mutant strain, which has a low glucan synthesis ability. Conversely, challenge with the <i>rgpI</i> deletion mutant strain resulted in the lowest number of luminescent organs, with a lower intensity and attenuated inflammation. Furthermore, all the mice inoculated with the <i>rgpI</i> deletion mutant strain survived, whereas not all the mice inoculated with the parent strain survived. Collectively, these results suggest that RgpI is involved in the systemic pathogenicity of <i>S. mutans</i> UA159.