LETTER TO THE EDITOR
Reply
Yuk-ki Wonga,
Keith D. Dawkinsa and
Michael E. Warda
a Wessex Cardiothoracic Unit Southampton General Hospital Tremona Road Southampton, Hampshire S016 6YD United Kingdom
We thank Drs. Taylor-Robinson and Thomas for their interest in our study, which found circulating Chlamydia pneumoniae (C. pneumoniae) DNA to be associated with coronary artery disease (CAD) in men but not women (1). The association in men was moderate, with an odds ratio of 3.2 (95% confidence interval 1.1 to 8.9), and this was stronger than that reported in most serologic studies (2). We discussed possible reasons for the lack of an association in women, but because the number of male subjects was over twice that of females, the statistical power to detect a difference was strongest for men. In our study, patients and control subjects were defined according to the presence of CAD by angiographic criteria, an approach taken by other studies of C. pneumoniae and CAD (2), and, indeed, by studies that have investigated other coronary risk factors. We can justifiably claim that we have found an association between C. pneumoniae DNA and clinically significant atherosclerosis.
Our study and that of Boman et al. (3) are still the only published reports on circulating C. pneumoniae DNA and CAD, and we pointed out the differences in the reported prevalence of C. pneumoniae DNA. In our view, the finding that circulating C. pneumoniae DNA was found in 46% of a healthy, blood-donating population (3) is remarkable and an extraordinarily high level for any bacterium. However, although our study was far larger than Boman’s, further work is required to clarify the situation, but we cannot comment on the unpublished data of the correspondents or their observations.
It would be generally accepted that evidence of current C. pneumoniae infection should be found before prescribing antibiotics to patients with CAD. At present, the presence of circulating C. pneumoniae DNA is the most accurate method of diagnosing current infection and is therefore a means of identifying suitable patients for intervention trials. This was also a view held by the correspondents (4), and we are therefore surprised by their statement that "fortunately," current antibiotic trials are being undertaken with complete disregard for the PBMC C. pneumoniae status. Fortunately, investigators running such trials do realize the potential importance of such a test (5).
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References
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1. Wong Y, Dawkins KD, Ward ME. Circulating Chlamydia pneumoniae DNA as a predictor of coronary artery disease. J Am Coll Cardiol. 1999;34:1435–1439[Abstract/Free Full Text]
2. Wong YK, Gallagher PJ, Ward ME. Chlamydia pneumoniae and atherosclerosis. Heart. 1999;81:232–238[Abstract/Free Full Text]
3. Boman J, Soderberg S, Forsberg J, et al. High prevalence of Chlamydia pneumoniae DNA in peripheral blood mononuclear cells in patients with cardiovascular disease and in middle-aged blood donors. J Infect Dis. 1998;178:274–277[Medline]
4. Taylor-Robinson D, Thomas BJ. Chlamydia pneumoniae in arteries: the facts, their interpretation, and future studies. J Clin Pathol. 1998;51:793–797[Medline]
5. Grayston JT, Jackson LA, Kennedy WJ, et al. Secondary prevention trials for coronary artery disease with antibiotic treatment for Chlamydia pneumoniae: design issues. Am Heart J. 1999;138:S545–S549[CrossRef][Medline]
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