Abstract Body: Background: We reported that cariogenic bacteria Streptococcus mutans expressing a collagen-binding protein Cnm on its bacterial surface is associated with the prevalence of intracerebral hemorrhage in retrospective observational studies. However, a peak age of stroke onset in patients carrying Cnm-expressing S. mutans remains unknown.
Methods: A multicenter, prospective cohort study (RAMESSES: Risk assessment of Cnm-positive S. mutans in strokesurvivors; UMIN Clinical Trials Registry: UMIN000045559) was initiated in November 2018 with 14 Japanese domestic institutions. The main inclusion criteria were as follows: 1) aged ≥40 years; 2) patients who experienced stroke or transient ischemic attack (TIA) that developed within the past one year, and had old deep intracerebral hemorrhage or at least one deep CMB on T2* weighted brain magnetic resonance imaging. We compared the onset age of the stroke or TIA between the Cnm-expressing S. mutans carriers and noncarriers.
Results: Among 230 participants, the median age was 70 years [62–79], and 63 (27.4%) were women. This cohort included 138 patients with ischemic stroke, 60 patients with hemorrhagic stroke, 23 patients with ischemic and hemorrhagic stroke, 7 patients with TIA, and 2 patients with hemorrhagic stroke and TIA during the past one year. The number of the Cnm-expressing S. mutans carriers were 35 (15.2%). When divided by the median age, younger patients (<70 years) with stroke or TIA, compared to the older patients (≥70 years), had a higher carrier rate of Cnm-expressing S. mutans (22.7% vs. 8.3%, p < 0.001) and a lower prevalence of atrial fibrillation (6.4% vs. 22.5%, p = 0.001). Multivariate logistic regression analysis adjusted for sex, hypertension, and atrial fibrillation revealed that younger onset of stroke or TIA was independently associated with carriage of Cnm-positive S. mutans (adjusted odds ratio 1.26, 95% confidence interval 1.06–1.51; p = 0.009). Additionally, a tertile analysis based on age demonstrated the prevalence of Cnm-expressing S. mutans decreased as the age of stroke or TIA onset increased (24.6%, 12.5%, 9.9%; p for trend = 0.014).
Conclusion: Oral carriage of Cnm-expressing S. mutans may confer a risk of earlier stroke or TIA. This finding suggests that targeting Cnm-positive S. mutans could be a promising novel therapeutic approach for preventing stroke or TIA.