Harboring Cnm‐expressing Streptococcus mutans in the oral cavity relates to both deep and lobar cerebral microbleeds.

Background: Cerebral microbleeds (CMBs) influence long‐term prognoses of stroke patients. Streptococcus mutans expressing the collagen‐binding protein Cnm induces cerebrovascular inflammation, impairing blood brain barrier integrity and causing cerebral bleeding. Here, we examine the association of Cnm‐positive S. mutans with CMBs. Methods: Acute stroke patients were selected from a single‐center registry database. Oral carriage of Cnm‐positive or Cnm‐negative S. mutans was determined using polymerase chain reaction assays. The associations of Cnm‐positive S. mutans with CMB number and specifically the presence of >10 CMBs were examined using quasi‐Poisson and logistic regression models, respectively. Results: This study included 3154 stroke patients, of which 428 patients (median [interquartile range] age, 73.0 [63.0–81.0] years; 269 men [62.9%]) underwent oral bacterial examinations. In total, 326 patients harbored S. mutans. After excluding four patients without imaging data, we compared patients with Cnm‐positive (n = 72) and Cnm‐negative (n = 250) S. mutans. Harboring Cnm‐positive S. mutans was independently associated with the presence of >10 CMBs (adjusted odds ratio 2.20 [1.18–4.10]) and higher numbers of deep and lobar CMBs (adjusted risk ratio 1.61 [1.14–2.27] for deep; 5.14 [2.78–9.51] for lobar), but not infratentorial CMBs, after adjusting for age, sex, hypertension, stroke type, National Institutes of Health Stroke Scale score, and cerebral amyloid angiopathy. Conclusions: Harboring Cnm‐positive S. mutans was independently associated with a higher number of CMBs in deep and lobar locations. Reducing Cnm‐positive S. mutans in the oral cavity may serve as a novel therapeutic approach for stroke. [ABSTRACT FROM AUTHOR]