LAUSR

Objective: Increasing data supports the role of bacterial inflammation in adverse events of cardiovascular and cerebrovascular diseases. In our previous research, DNA of bacterial species found in coronary artery thrombus aspirates and ruptured cerebral aneurysms were mostly of endodontic and periodontal origin, where Streptococcus mitis group DNA was the most common. We hypothesized that the genomes of S mitis group could be identified in thrombus aspirates of patients with lower limb arterial and deep venous thrombosis. Methods: Thrombus aspirates and control blood samples taken from 42 patients with acute or acute‐on‐chronic lower limb ischemia (Rutherford I‐IIb) owing to arterial or graft thrombosis (n = 31) or lower limb deep venous thrombosis (n = 11) were examined using a quantitative real‐time polymerase chain reaction to detect all possible bacterial DNA and DNA of S mitis group in particular. The samples were considered positive, if the amount of bacterial DNA in the thrombus aspirates was 2‐fold or greater in comparison with control blood samples. Results: In the positive samples the mean difference for the total bacterial DNA was 12.1‐fold (median, 7.1), whereas the differences for S mitis group DNA were a mean of 29.1 and a median of 5.2‐fold. Of the arterial thrombus aspirates, 57.9% were positive for bacterial DNA, whereas bacterial genomes were found in 75% of bypass graft thrombosis with 77.8% of the prosthetic grafts being positive. Of the deep vein thrombus aspirates, 45.5% contained bacterial genomes. Most (80%) of bacterial DNA‐positive cases contained DNA from the S mitis group. Previous arterial interventions were significantly associated with the occurrence of S mitis group DNA (P = .049, Fisher's exact test). Conclusions: This is the first study to report the presence of bacterial DNA, predominantly of S mitis group origin, in the thrombus aspirates of surgical patients with lower limb arterial and deep venous thrombosis, suggesting their possible role in the pathogenesis of thrombotic events. Additional studies will, however, be needed to reach a final conclusion. Clinical Relevance: This is the first study to report the presence of bacterial DNA, predominantly of Streptococcus mitis group origin, in the thrombus aspirates of patients with lower limb arterial and deep venous thrombosis. Interestingly, the occurrence of S mitis group DNA seems to be significantly associated with previous vascular manipulations. It remains to be established whether these findings play a role in the actual thrombosis.