Background:Conventional risk factors cannot completely explain the pathogenesis of atherosclerosis. A possible role of some microorganisms, particularly Chlamydia pneumoniae and Helicobacter pylori has been proposed in the pathogenesis of atherosclerosis for a long time, but it is still an unresolved issue. We explored the presence of Chlamydia pneumoniae and Helicobacter pylori DNA in carotid artery atherosclerotic plaques by using “polymerase chain reaction”.

Methods: Onehundredfour consecutive patients with various types of atherosclerotic diseases who admitted to our center for surgical intervention were included in this prospective study. Fifty-two atherosclerotic plaque specimens that were obtained from carotid arteries of the cases who had carotid endarterectomy constituted the study group and 52 specimens obtained from the macroscopically healthy regions of ascending aorta in cases who undergone coronary artery bypass grafting were the control group.

Results: Chlamydia pneumoniae DNA was detected in 16 (30.77%) of 52 atherosclerotic plaques and 1 (1.92%)of 52 macroscopically healthy ascending aorta wall specimens (p < 0.001). Helicobacter pylori DNA was detected in 9 (17.31%) of 52 atherosclerotic plaques and none of the controls (p = 0.003). Twenty-five of 52 plaques (48%) were positive either for Chlamydia pneumoniae or Helicobacter pylori.

Conclusion: Higher incidence of Chlamydia pneumoniae and Helicobacter pylori DNA in atherosclerotic plaques, compared to healthy vascular walls suggests that these microorganisms may play a role in the pathogenesis of atherogenesis.

Keywords : Atherosclerosis, Chlamydia pneumoniae, Helicobacter pylori, polymerase chain reaction