Measurement of Chlamydia pneumoniae bacterial load in peripheral blood mononuclear cells may be helpful to assess the state of chlamidial infection in patients with carotid atherosclerotic disease.

Background: Chlamydia pneumoniae has been repeatedly associated with atherosclerotic cardiovascular diseases.We investigated the pattern of distribution of C. pneumoniae among patients with carotid atherosclerotic disease evaluating chlamydial load in carotid plaque, peripheral blood mononuclear cells (PBMC) and lymph node from same patient. Methods and results: Thirty carotid plaques, 30 PBMC and 30 lymph nodes were examined by real-time PCR assay. C. pneumoniae DNA was detected, in carotid plaques, PBMC and lymph nodes in 11 patients; in carotid plaques and PBMC in five patients; in PBMC and lymph nodes in four patients; in lymph nodes in two patients; and in PBMC only in one patient. C. pneumoniae DNA in PBMC significantly coincided with the presence of the respective DNA in carotid plaque (p = 0.0001) and lymph node (p = 0.02). A higher chlamydial load was detected in PBMC than in lymph nodes and carotid plaques. More than 90% of patients with carotid plaques, PBMC and lymph nodes positive to C. pneumoniae were symptomatic, smokers, hypertensives, dyslipidemics and showed carotid plaques with rupture on the surface, hemorrhage and thrombosis. Conclusion: The measurement of chlamydial load in PBMC may be helpful in the future to assess the state of C. pneumoniae infection and the risk of developing sequelae.