Detection of diverse bacterial signatures in atherosclerotic lesions of patients with coronary heart disease

Background - Bacterial infection has been discussed as a potential etiologic factor in the pathophysiology of coronary heart disease (CHD). This study analyzes molecular phylogenies to systematically explore the presence, frequency, and diversity of bacteria in atherosclerotic lesions in patients with CHD. Methods and Results - We investigated 16S rDNA signatures in atherosclerotic tissue obtained through catheter-based atherectomy of 38 patients with CHD, control material from postmortem patients (n = 15), and heart-beating organ donors (n = 11) using clone libraries, denaturating gradient gel analysis, and fluorescence in situ hybridization. Bacterial DNA was found in all CHD patients by conserved PCR but not in control material or in any of the normal/unaffected coronary arteries. Presence of bacteria in atherosclerotic lesions was confirmed by fluorescence in situ hybridization. A high overall bacterial diversity of > 50 different species, among them Staphylococcus species, Proteus vulgaris, Klebsiella pneumoniae, and Streptococcus species, was demonstrated in > 1500 clones from a combined library and confirmed by denaturating gradient gel analysis. Mean bacterial diversity in atheromas was high, with a score of 12.33 +/- 3.81 (range, 5 to 22). A specific PCR detected Chlamydia species in 51.5% of CHD patients. Conclusions - Detection of a broad variety of molecular signatures in all CHD specimens suggests that diverse bacterial colonization may be more important than a single pathogen. Our observation does not allow us to conclude that bacteria are the causative agent in the etiopathogenesis of CHD. However, bacterial agents could have secondarily colonized atheromatous lesions and could act as an additional factor accelerating disease progression.