Chlamydia pneumoniae as an etiological agent in atherosclerosis from patients undergoing carotid endarterectomy or abdominal aortic aneurysm repair

A substantial amount of evidence in recent years based on seroepidemiological, electron microscopy and cytochemical studies suggests an association between Chlamydia pneumoniae and the development of atherosclerotic cardiovascular disease. However, the inability to demonstrate on a routine basis viable C. pneumoniae in the majority of studies on atherosclerotic tissues continues to raise the question of direct involvement of this organism in the development of atherosclerotic plaques. C. pneumoniae DNA has also been demonstrated in peripheral blood mononuclear cells (PBMC) in patients with atherosclerosis, as well as in healthy middle aged blood donors. Using a C. pneumoniae specific primer for polymerase chain reaction (PCR) and heat treatment of H-292 cells with multiple centrifugations for culture, we looked for evidence of C. pneumoniae in atherosclerotic tissue and PBMC from 112 patients undergoing elective abdominal aortic aneurysm (AAA) repair or carotid endarterectomy (CE). The PBMC from 51 age-matched healthy controls were also analyzed for the presence of this organism. This study was successful at detecting C. pneumoniae in 90/112 (80%) of the atherosclerotic plaques by PCR, and in 94/108 (87%) by culture. In addition, C. pneumoniae was identified by PCR in the PBMC of 78/100 (78%) patients with atherosclerosis. Viable organisms were demonstrated in the PBMC of 43/46 (94%) from these patients. C. pneumoniae was also detected by PCR in the PBMC of 37/51 (73%) age-matched controls and by culture in 33/51 (65%) of these individuals. These results provide further evidence for the involvement of an infectious agent in the development of atherosclerosis. The presence of C. pneumoniae within PBMC of patients with cardiovascular disease may result in a diagnostic tool for identification of individuals who may eventually be targeted for antibiotic therapy.