This study investigates the microbial composition of atherosclerotic plaques, oral, and gut samples in patients with atherosclerosis to explore the potential role of oral and gut microbiota in the development of atherosclerosis. Using qPCR, the researchers found that bacterial DNA was present in atherosclerotic plaques, with its amount correlating with the number of leukocytes. Pyrosequencing of 16S rRNA genes revealed that Chryseomonas was present in all atherosclerotic plaque samples, while Veillonella and Streptococcus were common in most. The abundance of Veillonella and Streptococcus in plaques correlated with their abundance in the oral cavity. Several bacterial phylotypes were shared between atherosclerotic plaques and oral or gut samples within the same individual. Additionally, several bacterial taxa in the oral cavity and gut correlated with plasma cholesterol levels. These findings suggest that bacteria from the oral cavity and possibly the gut may contribute to disease markers of atherosclerosis.This study investigates the microbial composition of atherosclerotic plaques, oral, and gut samples in patients with atherosclerosis to explore the potential role of oral and gut microbiota in the development of atherosclerosis. Using qPCR, the researchers found that bacterial DNA was present in atherosclerotic plaques, with its amount correlating with the number of leukocytes. Pyrosequencing of 16S rRNA genes revealed that Chryseomonas was present in all atherosclerotic plaque samples, while Veillonella and Streptococcus were common in most. The abundance of Veillonella and Streptococcus in plaques correlated with their abundance in the oral cavity. Several bacterial phylotypes were shared between atherosclerotic plaques and oral or gut samples within the same individual. Additionally, several bacterial taxa in the oral cavity and gut correlated with plasma cholesterol levels. These findings suggest that bacteria from the oral cavity and possibly the gut may contribute to disease markers of atherosclerosis.