Detection of Chlamydia pneumoniae and Helicobacter pylori DNA in human atherosclerotic plaques by PCR

Chlamydia pneumoniae and Helicobacter pylori can cause persistent infections of the respiratory and gastrointestinal tract, respectively. It has been suggested that persistent infection of arteries with these bacteria can contribute to the development of atherosclerosis. The aims of this study were to determine the presence of C. pneumoniae and H. pylori DNA in atherosclerotic plaque samples by PCR and to evaluate the correlation between clinical status and DNA positivity of these bacteria. Eighty-five consecutive patients (mean age, 59 +/- 10; 75 male, 10 female) undergoing coronary artery bypass grafting, carotid endarterectomy, and surgery of the abdominal aorta for atherosclerotic obstructive lesions were included in the study. Forty-six endarterectomy specimens from the atherosclerotic lesions and 39 specimens from healthy regions of the ascending aorta, which were accepted as the control group, were excised. The presence of microorganism DNA in endarterectomy specimens was assessed by PCR. C. pneumoniae DNA was found in 12 (26%) of 46 endarterectomy specimens and none of the healthy vascular-wall specimens (P < 0.001), while H. pylori DNA was found in 17 (37%) of 46 endarterectomy specimens and none of the controls (P < 0.001). Either C. pneumoniae or H. pylori DNA was positive in 23 (50%) of 46 patients and none of the controls (P < 0. 001). Six of the atherosclerotic lesions showed coexistence of both of the microorganism DNAs. The presence of C. pneumoniae and H. pylori DNA in a considerable number of atherosclerotic plaques but their absence in healthy vascular wall supports the idea that they 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 high prevalence of atherosclerotic vascular disease.