A Review on the Role of Oral Bacteria in Stroke.

Emerging evidence suggests periodontitis may contribute to stroke risk via vascular inflammation and endothelial dysfunction, promoting atherothrombosis and atrial fibrillation. This review aims to synthesize the evidence on the presence of oral bacteria and their products in biological samples from stroke patients and assess their potential impact on stroke pathophysiology, clinical outcomes, and prognosis. We conducted a narrative review of epidemiological, serological, and molecular studies examining the presence of oral bacterial DNA, endotoxins and antibodies against oral pathogens in biological samples (blood, saliva and thrombi) from stroke patients. Seropositivity for periodontal pathogens in blood was associated with incident stroke, as well as with poorer prognosis. Oral bacterial DNA, mainly from Streptococcus spp. and Prevotella spp., was consistently detected in thrombi, whereas no DNA from classic periodontal pathogens was found. The presence of P. gingivalis antibodies in thrombi was associated with lower complete reperfusion rates, while Acinetobacter spp. and Enterobacteriaceae correlated with higher early adverse events and poorer prognosis. DNA detection was limited by low-biomass samples and methodological constraints. These findings support a potential link between periodontitis and ischemic stroke. However, further studies using improved molecular methods are needed to clarify underlying mechanisms and to assess the presence of periodontal pathogen DNA in thrombi.