Chlamydia pneumoniae may contribute to stroke, heart attacks

Analysis of available data suggests that Chlamydia pneumoniae, which causes “walking pneumonia,” may contribute to atherosclerosis (hardening of the arteries) and its complications, such as heart attack and stroke, according to a paper in the Dec. 4 issue of the Journal of the American Medical Association (JAMA).

Murat Kalayoglu of the Massachusetts Eye and Ear Infirmary, Peter Libby of Harvard-affiliated Brigham and Women’s Hospital, and Gerald Byrne of the University of Tennessee Health Science Center, searched MEDLINE and considered online resources, texts, meeting abstracts, and expert opinion for the association between Chlamydia pneumoniae (C pneumoniae) and atherosclerosis. They included five types of studies and extracted diagnostic, pathophysiologic, and therapeutic information from the selected literature.

“Atherosclerosis causes approximately half of all adult deaths in the Western hemisphere and continues to be a major health problem worldwide,” Kalayoglu, the lead author, said. “Traditional risk factors such as elevated cholesterol clearly contribute to these cardiovascular diseases, but leave some 40 percent of cases unexplained. Recent appreciation of atherosclerosis as a chronic, inflammatory disease has rekindled efforts to examine the role that infectious agents may play in atherogenesis.”

Much of this interest has focused on infection with C pneumoniae, stimulated by a variety of epidemiological, pathology-based, animal model, cell biology, and human antibiotic treatment studies. The possibility that a bacterium contributes to atherogenesis has high clinical interest, as C pneumoniae infection may represent a treatable risk factor in cardiovascular diseases. This article reviews the evidence implicating C pneumoniae in the pathogenesis of atherosclerosis.

“Overall, analysis of available data suggests that C pneumoniae is emerging as an additional risk factor in cardiovascular diseases,” Kalayoglu said. “At present, antibiotics are not indicated to prevent recurrent heart attacks or treat coronary disease. The preclinical evidence is significantly compelling to warrant careful further study.”