Circulating Chlamydia pneumoniae DNA as a predictor of coronary artery disease.

OBJECTIVE To determine whether current vascular Chlamydia pneumoniae (CPn) infection as diagnosed by circulating CPn DNA is more common in subjects with coronary artery disease (CAD). BACKGROUND Serological, pathological and animal studies have associated CPn with CAD and preliminary trials suggest antibiotics may prevent adverse coronary events. C. pneumoniae is thought to disseminate systemically within macrophages. We therefore detected CPn DNA in blood to determine whether its presence was a predictor of CAD. METHODS One thousand, two hundred and five subjects attending for diagnostic and interventional coronary arteriography were recruited. The mononuclear cell layer and platelets were separated from collected blood and the polymerase chain reaction (PCR) was used to detect CPn DNA. RESULTS Circulating CPn DNA was found in 8.8% of 669 men with CAD compared with 2.9% of 135 men with normal coronary arteries (odds ratio [OR] 3.2, 95% confidence interval [CI] 1.1-8.9). In men with CAD, those with CPn DNA had higher mean platelet counts than those without CPn DNA. Monocyte counts and indirect fibrinogen levels were also raised but not significantly so. By contrast, no association of circulating CPn DNA and CAD was seen in women. CONCLUSIONS Circulating CPn DNA is a predictor of CAD in men. Unlike serology, it is a specific indicator of current infection and is a means of identifying subjects who may potentially benefit from antichlamydial therapy.