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Chlamydia pneumoniae and atherosclerosis
Y K Wong1, P J Gallagher, M E Ward
1Wessex Cardiothoracic Unit, Southampton General Hospital, Tremona Road, Southampton, Hampshire SO16 6YD, UK. YW2@soton.ac.uk
Insights
Chronic Chlamydia pneumoniae infection may be linked to atherosclerosis, but more research is needed. Current evidence is inconclusive, and antibiotic use is not yet recommended for this condition.
Area of Science:
- Cardiovascular Medicine
- Infectious Diseases
- Microbiology
Background:
- Atherosclerosis is a major cause of cardiovascular disease.
- Chlamydia pneumoniae is a bacterium that has been investigated for its potential role in atherosclerosis.
- Understanding the link between chronic infections and cardiovascular health is crucial.
Purpose of the Study:
- To systematically review existing literature for evidence connecting chronic Chlamydia pneumoniae infection with atherosclerosis and acute coronary syndromes.
- To evaluate the strength and consistency of evidence from serological and pathological studies.
Main Methods:
- Comprehensive literature search of MEDLINE and Institute of Science and Information databases up to September 1998.
- Inclusion of serological and pathological studies examining Chlamydia pneumoniae and cardiovascular disease.
- Application of strict criteria for defining chronic infection (IgG and IgA presence) and assessing C. pneumoniae in atherosclerotic lesions.
Main Results:
- Most serological studies suggest an association between Chlamydia pneumoniae and atherosclerosis.
- However, studies meeting strict chronic infection criteria show similar numbers of positive and negative associations.
- Chlamydia pneumoniae is frequently detected in atherosclerotic vessels, but not exclusively in severe lesions. Animal models and early trials hint at exacerbation of atherosclerosis.
Conclusions:
- Conclusive evidence for Chlamydia pneumoniae's role in atherosclerosis is still lacking.
- Current data do not support routine antibiotic treatment for this association.
- Ongoing large-scale trials are expected to clarify the role of Chlamydia pneumoniae in cardiovascular disease.
Objective:
To review the literature for evidence that chronic infection with Chlamydia pneumoniae is associated with atherosclerosis and acute coronary syndromes.
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 pathological 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 characterised by the presence of both specific IgG and IgA, and serological studies were examined for associations that fulfilled these criteria. Pathological studies were also reviewed for evidence that the presence of C pneumoniae in diseased vessels is associated with the severity and extent of atherosclerosis.
Data Synthesis:
The majority of serological studies have shown an association between C pneumoniae and atherosclerosis. However, the number of cases in studies that have reported a positive association when using strict criteria for chronic infection is similar to the number of cases in studies which found no association. Nevertheless, the organism is widely found in atherosclerotic vessels, although it may not be at all diseased sites and is not confined to the most severe lesions. Rabbit models and preliminary antibiotic 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 elucidate the role of C pneumoniae.