Bacterial signatures in atherosclerotic lesions represent human commensals and pathogens

Background Various studies have suggested the involvement of infectious agents in chronic inflammatory diseases, including atherosclerosis. By using a novel subtraction broad-range PCR approach, we defined bacterial DNA signatures in surgically removed sterile abdominal aorta samples of patients with aortic atherosclerosis. Methods Partial bacterial 16S rDNA nucleotide sequences were determined using broad-range PCR from aortic samples of 20 patients, and from appropriate methodological controls. In all, 160 sequences from 16 clone libraries were studied. Results After subtraction analysis 16 clinically relevant bacterial sequence-types were identified among the patient samples, whereas 29 were discarded as potential methodological contaminants. On average 2.2 ± 1.2 different bacterial sequence-types were present in the nine true PCR-positive atheroma samples. Conclusions Many studies have reported the presence of a variety of bacterial sequences from atherosclerotic lesions. However, the results obtained with these PCR technologies may have been skewed by methodological contaminants. After our subtraction approach, 63% of the remaining sequence-types from sites of aortic atherosclerosis were related to those of known human pathogens. This may imply that advanced atherosclerotic plaques accumulate bacterial DNA.