Detecting Prokaryote-Specific Gene and Other Bacterial Signatures in Thrombi from Patients with Acute Ischemic Stroke

Background: and Purpose —Microbial infection has been associated with thrombogenesis. This study aimed to detect bacterium-specific genes and other signatures in thrombi from patients with acute ischemic stroke and to relate these signatures to clinical characteristics. Methods: —Blood samples were collected before thrombectomy procedures, and thrombus samples were obtained during the procedure. Identification and classification of bacteria in the samples were accomplished using 16S rRNA gene sequencing. Bacterium-specific structures were observed with transmission electron microscopy. Bacterium-specific biomarkers were detected through immunohistochemical staining. Results: —16S rRNA gene was detected in 32.1% of the thrombus samples from 81 patients. Bacillus (0.04% vs 0.00046%, p =0.003), Parabacteroides (0.20% vs 0.09%, p =0.029), Prevotella (1.57% vs 0.38%, p =0.010), Streptococcus (1.53% vs 0.29%, p =0.001), Romboutsia (0.18% vs 0.0070%, p =0.029), Corynebacterium (1.61% vs 1.26%, p =0.026) and Roseburia (0.53% vs 0.05%, p =0.005) exhibited significantly higher abundance in thrombi compared to arterial blood. Bacteria-like structures were observed in 22 (27.1%), while whole bacteria-like structures were observed in 7 (8.6%) thrombi under transmission electron microscopy. Immunohistochemical staining detected bacterium-specific monocyte/macrophage markers in 51 (63.0%) out of 81 thrombi. Logistic regression analysis indicated that alcohol consumption was associated with a higher bacteria burden in thrombi (odds ratio =3.19; 95% CI, 1.10-9.27; p =0.033). Conclusion: —Bacterial signatures usually found in the oral cavity and digestive tract were detected in thrombi from patients with ischemic stroke. This suggests a potential involvement of bacterial infection in the development of thrombosis. Long-term alcohol consumption may potentially enhance this possibility.