Introduction: Poor oral hygiene had been recognized as a vascular risk factor. Recently, we showed that cnm gene positive Streptococcus mutans (cnm-positive S.mutans) encoding collagen-binding protein (CBP) was associated with intracerebral hemorrhage (ICH). Deep cerebral microbleeds (CMBs), a biomarker of hemorrhagic small vessel disease, is also associated with cnm-positive S.mutans in a population cohort study.
Hypothesis: In this study, we aim to ascertain the correlation in acute stroke setting and investigated whether other factors, collagen binding activities of each S.mutans strain’s CBP or inflammatory markers, effects in the correlation.
Methods: We enrolled 99 acute stroke patients between February and August 2014. S.mutans was isolated from saliva, and cnm-gene was screened using PCR technique and collagen binding activities was evaluated using type I collagen assay. CMBs were evaluated on T2* gradient-recalled echo MRI.
Result: 67 subjects with ischemic stroke, 5 with transient ischemic attack, and 27 with ICH were included. The presence of cnm-positive S. mutans was significantly associated with ICH [odds ratio vs. ischemic stroke, 3.8; 95% CI, 1.06-13.8], increased number of deep CMBs [median (IQR), 3 (2-9) vs. 0 (0-1), p=0.0002], and fibrinogen [361 (336-459) vs. 320 (274-365) mg/dl, p=0.01]. The relative ratio for number of deep CMBs, cnm-positive S.mutans was 2.2 [95%CI 1.1-4.7] after adjustment of age, sex, systolic blood pressure and creatinine clearance. In subjects positive for S. mutans, collagen binding activity was positively correlated with the number of deep CMBs [γ=0.054; R2, 0.405; p<0.0001].
Conclusions: In acute stroke setting, we ascertained that cnm-positive S.mutans is independently associated with deep CMBs and ICH, and inflammation may have a mechanistic link.