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 16 S rRNA gene sequencing. Bacterium-specific structures were observed with transmission electron microscopy. Bacterium-specific biomarkers were detected through immunohistochemical staining.

Results: 16 S 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.