Tuesday, October 9, 2007

IDSA: No Evidence of Infectious Link to Coronary Disease Revealed

IDSA: No Evidence of Infectious Link to Coronary Disease Revealed


SAN DIEGO, Oct. 8 -- The infectious link to coronary artery disease, if there is one, remained as elusive as ever after scrutiny of peripheral blood mononuclear cells (PMBCs), investigators said here.

The examination of PMBCs from patients with coronary disease failed to turn up any evidence of Chlamydia pneumoniae, Sarah West, M.D., of Oregon Health & Science University in Portland reported at the Infectious Diseases Society of America meeting.

However, Dr. West and colleagues are not ready to close the door on investigation of an infectious etiology for coronary disease.

"All we can say on the basis of this work is that we were unable to detect the pathogen with the methods we used," said Dr. West. "We're confident in our results, but the data on human atheromas and from animal models are just too compelling to say there is nothing to this."

Previous studies of C. pneumoniae and coronary disease have yielded mixed results. Nucleic acid from the pathogen has been reported in 0% to 90% of atherosclerotic plaques. Similar variation has emerged from studies of C. pneumoniae nucleic acid in PBMCs of patients with coronary disease.

"I think our study differs from some of the others in that we used a very sensitive PCR assay, and we performed the assay three times with each specimen to ensure reliability," said Dr. West. "We also sent samples to an outside laboratory for confirmation."

Investigators tested the theory that C. pneumoniae spread to atherosclerotic plaque by PBMCs or vice versa would be detectable and serve as a marker for coronary disease. The study involved 86 patients with angiographically proven coronary disease and 90 age- and sex-matched controls without coronary disease or modifiable risk factors for coronary disease.

PBMCs in blood samples from patients and controls were probed for C. pneumoniae DNA and RNA by means of two different real-time PCR assays. Additionally, microimmunofluorescence assays were used to screen specimens for IgG for C. pneumoniae.

Three fourths of the patients and controls had serologic evidence of prior exposure to C. pneumoniae, as determined by microimmunofluorescence. Even so, none of the patients or controls had evidence of C. pneumoniae nucleic acid in PBMCs.

Samples sent to an outside laboratory yielded the same results.

"Our results were uniformly negative, using highly sensitive PCR techniques," said Dr. West. "The results indicate that PBMCs can't be used as a means of determining whether C. pneumoniae is in atheromatous lesions and that the presence or absence of C. pneumoniae nucleic acid in PBMCs is not a useful risk factor for coronary artery disease."

Primary source: Infectious Diseases Society of America

Source reference:

West SK et al. "No evidence of circulating C. pneumoniae nucleic acid in patients with coronary artery disease (CAD) or healthy controls." Infectious Diseases Society of American 45th Annual Meeting. Oct. 4-7, 2007. San Diego. Final Program and Abstracts. Abstract 464.

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