Abstract

Persistent infection of arteries with organisms such as Chlamydia pneumoniae was previously found to contribute to the development of atherosclerosis. We investigate the presence of C. pneumoniae in atherosclerotic plaque by polymerase chain reaction and direct immunofluorescence assay, and we examine the correlation between clinical status and the presence of this bacterium in Iran. The study group consisted of 33 atherosclerotic plaque specimens from the arteries (26 coronary and 7 abdominal aorta) of patients who had undergone coronary artery bypass grafting surgery (CABG). The control group consisted of 31 specimens: 12 from biopsies of macroscopically healthy regions of the ascending aorta in patients who had undergone CABG and 19 autopsy specimens of normal coronary arteries. C. pneumoniae DNA and antigen were found in 6 (18) and 7 (21) of 33 endarterectomy specimens, respectively. C. pneumoniae was not detected in the control group by either method. The presence of C. pneumoniae in atherosclerotic plaques and its absence in healthy vessels supports the idea that C. pneumoniae may have a role in the development of atherosclerosis, especially in countries where infection is prevalent and where conventional risk factors fail to explain the exact reason for the high prevalence of atherosclerotic vascular disease.