Chlamydia pneumoniae and atherosclerosis

Objective-To review the literature evidence that chronic infection with Chl amydia pneumoniae is associated with atherosclerosis and acute coronary syn dromes. Data sources-MEDLINE and Institute of Science and Information bibliographic databases were searched at the end of September 1998. Indexing terms used were chlamydi*, heart, coronary, and atherosclerosis. Serological and patho logical studies published as papers in any language since 1988 or abstracts since 1997 were selected. Data extraction-It was assumed that chronic C pneumoniae infection is chara cterised by the presence of both specific IgG and IgA, and serological stud ies were examined for associations that fulfilled these criteria. Pathologi cal studies were also reviewed for evidence that the presence of C pneumoni ae in diseased vessels is associated with the severity and extent of athero sclerosis. Data synthesis-The majority of serological studies have shown an associatio n between C pneumoniae and atherosclerosis. However, the number of cases in studies that have reported a positive association when using strict criter ia for chronic infection is similar to the number of cases in studies which found no association. Nevertheless, the organism is widely found in athero sclerotic vessels, although it may not be at all diseased sites and is not confined to the most severe lesions. Rabbit models and preliminary antibiot ic trials suggest that the organism might exacerbate atherosclerosis. Conclusion-More evidence is required before C pneumoniae can be accepted as playing a role in atherosclerosis. Although use of antibiotics in routine practice is not justified, large scale trials in progress will help to eluc idate the role of C pneumoniae. (Heart 1999;81:232-238).