Chlamydia pneumoniae DNA is more frequent in advanced than in mild atherosclerosis lesions.

There is growing evidence of an association between Chlamydia pneumoniae infection and atherosclerosis. By using polymerase chain reaction (PCR), we detected the presence of C. pneumoniae DNA in 16 of 92 (17%) arterial specimens with severe atherosclerotic lesions, and in 3 of 109 (3%) such specimens with mild atherosclerotic lesions (p < 0.01) from 49 cases with an autopsy diagnosis of cardiac death and 5 patients who underwent vascular reconstructive surgery. 14 of the 54 cases (28%) were C. pneumoniae-positive in at least 1 vascular sample. 12 of the 14 (86%) PCR positive cases were aged 60 y or older. Normal pulmonary artery specimens from 24 autopsy cases, used as a methodological control, tested negative. The levels of low density lipoprotein cholesterol and triglycerides were significantly lower in the PCR-positive cases than in the PCR-negative cases (p < 0.05). Importantly, 11 of the 14 PCR-positive cases had only 1 risk factor for atherosclerotic cardiovascular disease, whereas all PCR-negative cases had multiple risk factors (p < 0.05). Our data support the idea that C. pneumoniae may be involved in the development of atherosclerosis in humans, especially in cases where classic risk factors are not identified to explain the incidence of atherosclerotic vascular disease.