Role of Chlamydia pneumoniae in cardiovascular disease

Cardiovascular disease (CAD) is the leading cause of death in developed countries. The cause is multifactorial. A substantial proportion of patients with CAD do not have traditional risk factors. Infectious diseases may play a role in these cases, or they may intensify the effect of the risk factors. The association of CAD and Chlamydia pneumoniae infection is firmly established, but causality is yet to be proven. We investigated their presence in carotid atherosclerotic plaques. One-hundred two atherosclerotic plaques in dead patients were studied. The highly sensitive polymerase chain reaction method was employed with primers specific for this agent. PCR targeting the 16S rRNA gene and a nested PCR targeting the ompA gene were performed to detect C pneumoniae DNA. The presence of Chlamydia DNA was detected in 22 (23.3%) samples. The following risk factors were found among these 23 C. pneumoniae-infected cases: low HDL in 8 (34.8%), hypertension in 5 (21.7%), diabetes mellitus in 4 (17.4%), smoking in 11 (47.8%) and family history of cardiovascular disease in 6 (26.1%). The presence of Chlamydia DNA supports the hypothesis that this agent is associated with atherosclerosis.