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.