Chlamydia pneumoniae strain TWAR antibody and angiographically demonstrated coronary artery disease

Chlamydia pneumoniae and Mycoplasma pneumoniae as two Emerging Risk Factors in Atherosclerosis: Meta-Analysis Study and Systematic Review

BACKGROUND

Previous studies suggested an association between Chlamydia pneumoniae and Mycoplasma pneumonia with atherosclerosis, separately. Until now, according to inconsistent information, the relationship between C.pneumoniae and M.pneumoniae with atherosclerosis is controversial.

OBJECTIVE

the aim of this study, investigate of the association between C.pneumoniae and M.pneumoniae as two separate risk factors with atherosclerosis by systematic review and meta-analysis study.

METHODS

We searched databases such as Pubmed, SID, Magiran, Google scholar and Iranmedex using the following keywords in English and Persian language as C. pneumoniae , M. pneumoniae and atherosclerosis. Data were analyzed with meta-analysis and a random effect model. Also, in this study Heterogeneity of articles were estimated by using I2 index. Finally, data was analyzed with STAT (version 11.2) Results: Among thirty-eight articles for C. pneumoniae and five articles for M. pneumoniae individually reviewed that included 2980 samples for M. pneumoniae and 23298 samples for C. pneumoniae, result demonstrated that association between M. pneumoniae and C. pneumoniae with atherosclerosis is significant with OR (odd ratio) = 1.58 (95% Confidence Interval (CI): 1.00 to 2.50), OR (odd ratio) = 2.25(95% Confidence Interval (CI): 1.91 to 2.64), respectively.

CONCLUSION

This systematic review study provides strong evidence for the role of persistent bacterial infection such as M. pneumoniae and C. pneumoniae in potential atherosclerosis. Thus, a novel way should be employed for the complete management of bacterial infection.

Antibiotics for secondary prevention of coronary heart disease

BACKGROUND

Coronary heart disease is the leading cause of mortality worldwide with approximately 7.4 million deaths each year. People with established coronary heart disease have a high risk of subsequent cardiovascular events including myocardial infarction, stroke, and cardiovascular death. Antibiotics might prevent such outcomes due to their antibacterial, antiinflammatory, and antioxidative effects. However, a randomised clinical trial and several observational studies have suggested that antibiotics may increase the risk of cardiovascular events and mortality. Furthermore, several non-Cochrane Reviews, that are now outdated, have assessed the effects of antibiotics for coronary heart disease and have shown conflicting results. No previous systematic review using Cochrane methodology has assessed the effects of antibiotics for coronary heart disease.

OBJECTIVES

We assessed the benefits and harms of antibiotics compared with placebo or no intervention for the secondary prevention of coronary heart disease.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, SCI-EXPANDED, and BIOSIS in December 2019 in order to identify relevant trials. Additionally, we searched TRIP, Google Scholar, and nine trial registries in December 2019. We also contacted 11 pharmaceutical companies and searched the reference lists of included trials, previous systematic reviews, and other types of reviews.

SELECTION CRITERIA

Randomised clinical trials assessing the effects of antibiotics versus placebo or no intervention for secondary prevention of coronary heart disease in adult participants (≥18 years). Trials were included irrespective of setting, blinding, publication status, publication year, language, and reporting of our outcomes.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse event according to the International Conference on Harmonization - Good Clinical Practice (ICH-GCP), and quality of life. Our secondary outcomes were cardiovascular mortality, myocardial infarction, stroke, and sudden cardiac death. Our primary time point of interest was at maximum follow-up. Additionally, we extracted outcome data at 24±6 months follow-up. We assessed the risks of systematic errors using Cochrane 'Rosk of bias' tool. We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes. We calculated absolute risk reduction (ARR) or increase (ARI) and number needed to treat for an additional beneficial outcome (NNTB) or for an additional harmful outcome (NNTH) if the outcome result showed a beneficial or harmful effect, respectively. The certainty of the body of evidence was assessed by GRADE.

MAIN RESULTS

We included 38 trials randomising a total of 26,638 participants (mean age 61.6 years), with 23/38 trials reporting data on 26,078 participants that could be meta-analysed. Three trials were at low risk of bias and the 35 remaining trials were at high risk of bias. Trials assessing the effects of macrolides (28 trials; 22,059 participants) and quinolones (two trials; 4162 participants) contributed with the vast majority of the data. Meta-analyses at maximum follow-up showed that antibiotics versus placebo or no intervention seemed to increase the risk of all-cause mortality (RR 1.06; 95% CI 0.99 to 1.13; P = 0.07; I² = 0%; ARI 0.48%; NNTH 208; 25,774 participants; 20 trials; high certainty of evidence), stroke (RR 1.14; 95% CI 1.00 to 1.29; P = 0.04; I² = 0%; ARI 0.73%; NNTH 138; 14,774 participants; 9 trials; high certainty of evidence), and probably also cardiovascular mortality (RR 1.11; 95% CI 0.98 to 1.25; P = 0.11; I²= 0%; 4674 participants; 2 trials; moderate certainty of evidence). Little to no difference was observed when assessing the risk of myocardial infarction (RR 0.95; 95% CI 0.88 to 1.03; P = 0.23; I² = 0%; 25,523 participants; 17 trials; high certainty of evidence). No evidence of a difference was observed when assessing sudden cardiac death (RR 1.08; 95% CI 0.90 to 1.31; P = 0.41; I² = 0%; 4520 participants; 2 trials; moderate certainty of evidence). Meta-analyses at 24±6 months follow-up showed that antibiotics versus placebo or no intervention increased the risk of all-cause mortality (RR 1.25; 95% CI 1.06 to 1.48; P = 0.007; I² = 0%; ARI 1.26%; NNTH 79 (95% CI 335 to 42); 9517 participants; 6 trials; high certainty of evidence), cardiovascular mortality (RR 1.50; 95% CI 1.17 to 1.91; P = 0.001; I² = 0%; ARI 1.12%; NNTH 89 (95% CI 261 to 49); 9044 participants; 5 trials; high certainty of evidence), and probably also sudden cardiac death (RR 1.77; 95% CI 1.28 to 2.44; P = 0.0005; I² = 0%; ARI 1.9%; NNTH 53 (95% CI 145 to 28); 4520 participants; 2 trials; moderate certainty of evidence). No evidence of a difference was observed when assessing the risk of myocardial infarction (RR 0.95; 95% CI 0.82 to 1.11; P = 0.53; I² = 43%; 9457 participants; 5 trials; moderate certainty of evidence) and stroke (RR 1.17; 95% CI 0.90 to 1.52; P = 0.24; I² = 0%; 9457 participants; 5 trials; high certainty of evidence). Meta-analyses of trials at low risk of bias differed from the overall analyses when assessing cardiovascular mortality at maximum follow-up. For all other outcomes, meta-analyses of trials at low risk of bias did not differ from the overall analyses. None of the trials specifically assessed serious adverse event according to ICH-GCP. No data were found on quality of life.

AUTHORS' CONCLUSIONS

Our present review indicates that antibiotics (macrolides or quinolones) for secondary prevention of coronary heart disease seem harmful when assessing the risk of all-cause mortality, cardiovascular mortality, and stroke at maximum follow-up and all-cause mortality, cardiovascular mortality, and sudden cardiac death at 24±6 months follow-up. Current evidence does, therefore, not support the clinical use of macrolides and quinolones for the secondary prevention of coronary heart disease. Future trials on the safety of macrolides or quinolones for the secondary prevention in patients with coronary heart disease do not seem ethical. In general, randomised clinical trials assessing the effects of antibiotics, especially macrolides and quinolones, need longer follow-up so that late-occurring adverse events can also be assessed.

Genital Chlamydia infection in hyperlipidemic mouse models exacerbates atherosclerosis

BACKGROUND AND AIMS

Atherosclerosis is a chronic inflammatory disease, and recent studies have shown that infection at remote sites can contribute to the progression of atherosclerosis in hyperlipidemic mouse models. In this report, we tested the hypothesis that genital Chlamydia infection could accelerate the onset and progression of atherosclerosis.

METHODS

Apolipoprotein E (Apoe^-/-) and LDL receptor knockout (Ldlr^-/-) mice on a high-fat diet were infected intra-vaginally with Chlamydia muridarum. Atherosclerotic lesions on the aortic sinuses and in the descending aorta were assessed at 8-weeks post-infection. Systemic, macrophage, and vascular site inflammatory responses were assessed and quantified.

RESULTS

Compared to the uninfected groups, infected Apoe^-/- and Ldlr^-/- mice developed significantly more atherosclerotic lesions in the aortic sinus and in the descending aorta. Increased lesions were associated with higher circulating levels of serum amyloid A-1, IL-1β, TNF-α, and increased VCAM-1 expression in the aortic sinus, suggesting an association with inflammatory responses observed during C. muridarum infection. Genital infection courses were similar in Apoe^-/-, Ldlr^-/-, and wild type mice. Further, Apoe^-/- mice developed severe uterine pathology with increased dilatations. Apoe-deficiency also augmented cytokine/chemokine response in C. muridarum infected macrophages, suggesting that the difference in macrophage response could have contributed to the genital pathology in Apoe^-/- mice.

CONCLUSIONS

Overall, these studies demonstrate that genital Chlamydia infection exacerbates atherosclerotic lesions in hyperlipidemic mouse and suggest a novel role for Apoe in full recovery of uterine anatomy after chlamydial infection.

Atherosclerosis and infection: is the jury still not in?

Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.

Periodontal disease and atherosclerotic vascular disease: does the evidence support an independent association?: a scientific statement from the American Heart Association

A link between oral health and cardiovascular disease has been proposed for more than a century. Recently, concern about possible links between periodontal disease (PD) and atherosclerotic vascular disease (ASVD) has intensified and is driving an active field of investigation into possible association and causality. The 2 disorders share several common risk factors, including cigarette smoking, age, and diabetes mellitus. Patients and providers are increasingly presented with claims that PD treatment strategies offer ASVD protection; these claims are often endorsed by professional and industrial stakeholders. The focus of this review is to assess whether available data support an independent association between ASVD and PD and whether PD treatment might modify ASVD risks or outcomes. It also presents mechanistic details of both PD and ASVD relevant to this topic. The correlation of PD with ASVD outcomes and surrogate markers is discussed, as well as the correlation of response to PD therapy with ASVD event rates. Methodological issues that complicate studies of this association are outlined, with an emphasis on the terms and metrics that would be applicable in future studies. Observational studies to date support an association between PD and ASVD independent of known confounders. They do not, however, support a causative relationship. Although periodontal interventions result in a reduction in systemic inflammation and endothelial dysfunction in short-term studies, there is no evidence that they prevent ASVD or modify its outcomes.

Chlamydophila pneumoniae infection leads to smooth muscle cell proliferation and thickening in the coronary artery without contributions from a host immune response

Chlamydophila pneumonia (C. pneumonia) infection has been associated with the progression of atherosclerosis. It remains unclear, however, whether C. pneumoniae in the absence of an immune response can alone initiate atherogenic events within a complex vessel environment. Left anterior descending coronary arteries isolated from porcine hearts were dissected and placed in culture medium for 72 hours before infection with C. pneumoniae. C. pneumoniae replicated within the arterial wall for the duration of the experiment (up to 10 days). A significant increase in chlamydial-HSP60 protein expression from day 2 to 10 post-infection (pi) indicated the presence of metabolically active C. pneumonia within infected vessels. Significant arterial thickening in infected coronary segments was observed by a considerable decrease in the ratio of lumen to total vessel area (48 +/- 3% at day 4 pi versus 23 +/- 3% at day 10 pi) and a significant increase in the ratio of media to luminal area (113 +/- 16% at day 4 pi versus 365 +/- 65% at day 10 pi). Structural changes were accompanied by an up-regulation of host HSP60 and proliferating cell nuclear antigen expression levels. Immunohistochemical staining confirmed proliferating cell nuclear antigen expression to be primarily localized within smooth muscle cells of the medial area. These results demonstrate that C. pneumoniae infection can stimulate arterial thickening in a complex vessel environment without the presence of a host immune response and further supports the involvement of HSP60 in this action.

Chronic infection in the etiology of atherosclerosis--the case for Chlamydia pneumoniae

Established cardiovascular risk factors do not fully explain the variations in the prevalence and severity of coronary heart disease. Recent evidence suggests that common chronic infections may contribute, either by direct or indirect mechanisms, to the etiology and/or progression of coronary atherosclerosis. Of the candidate infectious agents implicated, Chlamydia pneumoniae has emerged as the most likely pathogen to have a causal role. Evidence for this is based on seroepidemiologic, pathologic, and laboratory-based evidence, in addition to recent small-scale antibiotic intervention studies. Concerted efforts are now focused on the design of large prospective trials with antibiotics active against C. pneumoniae in the secondary prevention of coronary heart disease.

Lack of association between prior infection with Chlamydia pneumoniae and acute or chronic coronary artery disease

BACKGROUND

Higher than normal serologic titers and the detection of bacteria within atheroma have suggested an association between Chlamydia pneumoniae (C. pneumoniae) infection and coronary heart disease (CHD), but the relationship has not been well established.

HYPOTHESIS

The study was designed to establish a lack of relationship between chronic C. pneumoniae infection and CHD.

METHODS

Chlamydia-specific IgG-antibody was assayed using an indirect immunofluorescence test in the serum of 159 patients with severe arterial disease and 203 patients with a heart valve prostheses and no demonstrable CHD. Fatal and nonfatal vascular events and systemic thromboembolism were recorded over a 2-year period.

RESULTS

In the arterial group 107 patients (67.3%) and in the valvular group 120/203 (59.1%) were positive for C. pneumoniae antibody. The number of patients with fatal or nonfatal vascular events (double end point) in the arterial and valvular groups was 23 and 2, respectively (p < .0001). Triple end points (fatal plus nonfatal vascular events plus thromboembolism) were also more frequent in the arterial group (p < 0.002). The prevalence of chlamydia antibody positivity was the same in the arterial and valvular groups, and the occurrence of clinical events was also the same for chlamydia-positive (227 patients) as for chlamydia-negative (135 patients). After adjustment for confounding variables, only arterial disease was a predictive factor for double (OR 17.0; 95% CI 3.94-73.3) or triple (OR 3.12; 95% CI 1.56-6.25) end points.

CONCLUSION

We find C. pneumoniae chronic infection not to be an independent risk factor for acute or chronic arterial disease.

Relationship between periodontal infections and systemic disease

Oral conditions such as gingivitis and chronic periodontitis are found worldwide and are among the most prevalent microbial diseases of mankind. The cause of these common inflammatory conditions is the complex microbiota found as dental plaque, a complex microbial biofilm. Despite 3000 years of history demonstrating the influence of oral status on general health, it is only in recent decades that the association between periodontal diseases and systemic conditions such as coronary heart disease and stroke, and a higher risk of preterm low birth-weight babies, has been realised. Similarly, recognition of the threats posed by periodontal diseases to individuals with chronic diseases such as diabetes, respiratory diseases and osteoporosis is relatively recent. Despite these epidemiological associations, the mechanisms for the various relationships remain unknown. Nevertheless, a number of hypotheses have been postulated, including common susceptibility, systemic inflammation with increased circulating cytokines and mediators, direct infection and cross-reactivity or molecular mimicry between bacterial antigens and self-antigens. With respect to the latter, cross-reactive antibodies and T-cells between self heat-shock proteins (HSPs) and Porphyromonas gingivalis GroEL have been demonstrated in the peripheral blood of patients with atherosclerosis as well as in the atherosclerotic plaques themselves. In addition, P. gingivalis infection has been shown to enhance the development and progression of atherosclerosis in apoE-deficient mice. From these data, it is clear that oral infection may represent a significant risk-factor for systemic diseases, and hence the control of oral disease is essential in the prevention and management of these systemic conditions.

Interaction between Chlamydia pneumoniae seropositivity, inflammation and risk factors for atherosclerosis in patients with severe coronary stenosis

OBJECTIVE

To investigate whether Chlamydia pneumoniae (Cpn) seropositivity in patients with suspected coronary artery disease (CAD) (n = 81) is associated with increases in markers of inflammation, the severity of coronary atherosclerosis, and traditional risk factors for cardiovascular events.

MATERIAL AND METHODS

The severity of coronary atherosclerosis was ranked by Gensini score. Inflammation and endothelial dysfunction were evaluated using white blood cell counts and levels of high-sensitivity C-reactive protein (hs-CRP), ferritin, tumour necrosis factor-alpha (TNF-alpha), interleukins 1beta and 6 (IL-1beta, IL-6), soluble intercellular adhesion molecule-1 (sICAM-1), E-selectin and oxidized LDL (oxLDL), and these were compared between Cpn-seropositive and seronegative individuals.

RESULTS

IgA and IgG Cpn seropositivity were significantly associated with the presence of CAD (p = 0.005) and were independent predictive factors for the severity of coronary atherosclerosis (p = 0.005). Elevated levels of IL-6 (p = 0.027) and triglyceride (p = 0.038) and low levels of high-density lipoprotein cholesterol (HDL-C) (p = 0.038) were significantly predicted by Cpn IgA and IgG seropositivity.

CONCLUSIONS

Seropositivity for Cpn is a risk factor for patients with significant angiographically documented coronary stenosis. Additionally, Cpn seropositivity was significantly associated with dyslipidemia and elevated IL-6, known risk factors for CAD. These observations indicate that Cpn infection may be one entry point to the causal or contributory pathways that lead to atherosclerosis and its clinical manifestations.

A randomized trial in patients undergoing percutaneous coronary angioplasty: roxithromycin does not reduce clinical restenosis but angioplasty increases antibody concentrations against Chlamydia pneumoniae

BACKGROUND

Elevated antibodies against Chlamydia pneumoniae have been associated with coronary artery disease. In patients undergoing percutaneous coronary angioplasty, we therefore investigated the effect of roxithromycin on symptomatic restenosis and determined antichlamydial antibodies as well as inflammatory and immunological parameters.

METHODS

A total of 327 patients undergoing coronary angioplasty were randomized to roxithromycin or placebo and followed-up for 1 year. Antibodies were determined by microimmunofluorescence and enzyme-linked immunosorbent assay; C-reactive protein, interleukin-10, tumor necrosis factor-alpha (TNF-alpha), and eotaxin were determined by enzyme-linked immunosorbent assay.

RESULTS

Although the frequency of restenosis was not affected by roxithromycin (25 restenoses vs 32 in the control group), antichlamydial antibodies increased during follow-up (anti-CP IgG +12 +/- 2%, P < .001). Concentrations of TNF-alpha and eotaxin increased as well (TNF-alpha +9 +/- 1% and eotaxin +10 +/- 2%) and correlated with antichlamydial antibody concentrations (TNF-alpha, r = 0.23, P = .02; eotaxin, r = 0.32, P = .002).

CONCLUSIONS

Treatment with roxithromycin was not associated with a reduction of symptomatic restenoses. During follow-up, a marked increase in antichlamydial antibodies, TNF-alpha, and eotaxin was observed, suggesting that angioplasty-induced plaque rupture induces a specific immunological response without activation of inflammatory mechanisms as represented by C-reactive protein. Whether this mechanism occurs in all plaque ruptures remains to be determined.

Relation of Chlamydia pneumoniae infection to documented coronary artery disease in Shiraz, Southern Iran

The possibility that infectious agents may trigger a cascade of reactions leading to inflammation, atherogenesis, and vascular thrombotic events has recently been raised. Chlamydia pneumoniae is one of those that have received the most investigative attention with respect to coronary artery disease (CAD). This study was undertaken for the first time in Shiraz, Iran to determine this relationship. A case-control study was conducted in 167 subjects (81 women and 86 men) who underwent coronary angiography at cardiac catheterization laboratories of Shiraz University of Medical Sciences Hospitals. Immunoglobulin G (IgG), and IgA antibodies to C. pneumoniae antigen were estimated in baseline serum samples from 109 patients (mean age 57 years) experiencing a coronary event and from their matched controls (n = 58, mean age 50 years) by ELISA method. The prevalence of IgG and IgA antibodies to C. pneumoniae did not show any case-control differences (82.6% vs 74.1% and 22% vs 15.5%, respectively). These results suggest that although C. pneumoniae was highly prevalent among these patients, it did not appear to be associated with angiographically documented CAD and cannot be regarded as a positive predictor for the development of acute coronary syndrome.

Persistent infection and vascular disease: a systematic review

More than 150 epidemiological or clinical studies have reported on associations between vascular disease and the presence of certain persistent bacterial and viral agents, or of clinical conditions (e.g., periodontal disease) that are associated with persistent infection. This article provides a review of such studies, particularly in relation to Helicobacter pylori, Chlamydia pneumoniae, dental disease and cytomegalovirus (CMV), as well as references to possible mechanisms. The association between coronary heart disease and H. pylori or between heart disease and dental disease may be accounted for by residual confounding. Although markers of C. pneumoniae infection are around twenty times more common in atherosclerotic plaques than in disease-free blood vessels, the sequence of infection and disease is uncertain. For CMV, a limited number of patients with classic atherosclerotic coronary heart disease have been investigated in seroepidemiological studies. For all such agents, better and larger seroepidemiological and pathology-based studies are needed to resolve these uncertainties, as well as - at some stage - large-scale, randomised intervention studies.

The mechanisms by which infectious agents may contribute to atherosclerosis and its clinical manifestations

Three infectious agents have recently gained considerable interest as potential pathogens in atherosclerosis and in its clinical manifestations: herpes simplex virus, cytomegalovirus, and Chlamydia pneumoniae. Chronic and often asymptomatic infections with these agents occur widely in the general population. These pathogens may affect atherosclerosis either directly or indirectly. Direct effects on vascular wall cells might include cell lysis, transformation, lipid accumulation, proinflammatory changes, and augmentation of procoagulant activity. Indirect systemic effects may involve induction of acute-phase proteins, establishment of a prothrombotic state, hemodynamic stress caused by tachycardia, increased cardiac output, or a regional inflammatory activation in response to systemic endotoxemia and cytokinemia. The effects of microbial infection, usually in combination with other risk factors (for example, smoking, hyperlipidemia, family history), might promote atherogenesis and eventually trigger acute coronary events.

Chlamydia pneumoniae IgG and the severity of coronary atherosclerosis

BACKGROUND: The aim of this study was to compare Chlamydia pneumoniae IgG and the extent of coronary atherosclerosis. METHODS: We investigated 92 patients with stable angina pectoris who underwent coronary angiography to assess chest pain. Before angiography, C. pneumoniae IgG was analyzed. The number of major coronary arteries (1-3) having at least one diameter narrowing (>/=50%) stenosis was determined. The patients were divided into two groups of equal size, according to C. pneumoniae IgG levels. One group included individuals with C. pneumoniae IgG levels exceeding 46 enzyme-immuno-units (EIU)/L and the other consisted of subjects with IgG concentrations below 46 EIU/L. RESULTS: Subjects with higher antibody concentrations had a more severe disease. The number of diseased arteries was 2.1+/-0.8 (S.D.) and 1.4+/-0.6 (S.D.) for the two groups, respectively. The difference is highly significant (p<0.0001). CONCLUSIONS: This study suggests a causative relationship between C. pneumoniae IgG and the degree of coronary atherosclerosis. It does not, however, prove causality.

Genomic, serologic, and clinical case-control study of Chlamydia pneumoniae and peripheral artery occlusive disease

OBJECTIVES

Chlamydia pneumoniae has been related to atherosclerotic disease in both seroepidemiologic and genomic studies. We performed a case-control study to determine seropositivity and DNA detection in arteries of patients with peripheral artery occlusive disease and of healthy subjects.

METHODS

The study included 64 patients with peripheral artery occlusive disease, and 50 control subjects who underwent varicose vein surgery, matched to the patient group for age, sex, and tobacco use. The fibrinogen level in all study subjects was measured as a marker of inflammation. Blood samples were taken from all subjects for determination of immunoglobulin (Ig) G elementary bodies (EB) against C pneumoniae with microimmunofluorescence (MIF) and enzyme-linked immunosorbent assay (ELISA), and of IgA EB with ELISA. The cutoff titers were 1:32 for MIF and 1.1 for ELISA. Biopsy specimens of arterial atheromatous plaque were obtained from patients, and of pudendal artery and saphenous vein from control subjects, and were studied with hemi-nested polymerase chain reaction.

RESULTS

There were no differences in fibrinogen level between patients and controls. The prevalence of IgG anti-EB with MIF was 78% in patients and 24% in control subjects (P =.0001; odds ratio [OR], 11.3; 95% confidence interval [CI], 4.7-27.2). Prevalence of IgG anti-EB with ELISA was 75% in patients and 16% in control subjects (P =.0001; OR, 15.7; 95% CI, 6.1-40). There were no differences in IgA anti-EB titers. Bacterial DNA was detected in 67% of atheromatous plaques versus 12% of pudendal arteries (P =.0001) and 4% of saphenous veins. A weak correlation was found between seropositivity and the presence of intravascular DNA.

CONCLUSIONS

Our results support the hypothesis that C pneumoniae is related to the pathogenesis of atherosclerotic peripheral artery occlusive disease.

CLINICAL RELEVANCE

This study explored the infectious hypothesis in the context of the pathogenesis of atherosclerosis. This hypothesis has been supported by findings that certain infectious agents can cause or accelerate the course of diseases in which the possibility of a microbial cause was not previously proposed, as in the case of peptic ulcer and spongiform encephalopathy. The present study demonstrated the presence of Chlamydia pneumoniae and seropositivity in atheromatous plaques in patients with peripheral artery occlusive disease. These results contribute to a body of research that is opening up the possibility of treating atherosclerotic disease with antibiotic agents, and preventing it with immunization.

Chlamydia pneumoniae and future risk in patients with coronary heart disease

AIM

To evaluate the association between previous exposure to Chlamydia pneumoniae and future coronary risk in patients with coronary heart disease.

METHODS

A prospective, nested, case-control design was used. The patient sample was derived from a trial study of bezafibrate for the treatment of coronary heart disease. Anti-Chlamydia pneumoniae antibodies (IgG and IgA) in the baseline sera of 136 patients who had coronary events during follow-up (mean 6.2 years) were compared with those in 136 age- and gender-matched patients from the same trial without subsequent coronary events.

RESULTS

Mean titers of IgG and IgA antibodies were similar in cases and controls. The relative odds of future coronary events in patients who were seropositive at baseline were 1.0 (95% CI, 0.54-1.84) for IgG and 0.74 (95% CI, 0.41-1.31) for IgA. The relative odds did not change after adjustment for multiple confounding variables. The risk of future coronary events did not increase with increasing anti-Chlamydia pneumoniae antibody titers.

CONCLUSIONS

Prior exposure to Chlamydia pneumoniae in patients with chronic coronary heart disease is not associated with increased risk of recurrent coronary events.

Chronic infection and coronary artery disease

On a variety of fronts, chronic infection has been found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. For the most part, these relationships are still just associations. Failure to confirm initial reports of serologic associations also has been common. Specific causative relationships on par with that determined between H pylori and peptic ulcer disease have not yet been established. Potential mechanisms whereby chronic infections may play a role in atherogenesis are myriad. In the case of C pneumoniae, the effect may result from direct vessel wall colonization that may damage the vessel either directly or indirectly by initiating immunologic responses. In other cases the effect may simply be that of enhancing the pre-existing chronic inflammatory response of the body to standard risk factors such as hyperlipidemia. Even though the infectious agent may not directly infect the vessel wall, it may perform its critical role from afar. Chronic infection might also influence pre-existing plaque by enhancing T-cell activation or other inflammatory responses that may participate in the destabilization of the intimal cap. Hence chronic infection may play a role either in the initiation, progression, or the destabilization of atherosclerotic plaques. The infectious agents with the most evidence to support an etiologic role in atherosclerosis include C pneumoniae and cytomegalovirus. Evidence is mounting for a variety of other potential agents including other herpes viruses, influenza, other specific bacteria (such as M pneumoniae), and chronic infections with common bacterial agents (periodontal disease, chronic bronchitis, and chronic urinary tract infection, among others) [191]. Future studies are expected to elucidate further the pathophysiologic relationship between chronic infection and atherosclerosis and to evaluate further the potential of a variety of treatment approaches, including antibiotics.

Joint effects of Chlamydia pneumoniae infection and classic coronary risk factors on risk of acute myocardial infarction

BACKGROUND

Although not in itself strongly predictive of coronary heart disease, Chlamydia pneumoniae infection could interact with classic risk factors in determining risk of acute myocardial infarction (AMI).

METHODS

We assessed C pneumoniae immunoglobulin (Ig) G and IgA titers and classic risk factors in 618 patients with AMI and in 967 controls.

RESULTS

IgG titers were not related to AMI, but a significant association was seen between IgA titers and AMI. Excess risk of AMI was noted mainly among patients with the highest IgA titers, such as those beyond 2.88 (the 95th percentile cutoff point in control subjects), showing a 1.8-fold increase in risk (odds ratio 1.75, 95% CI 1.04-2.92). Classic risk factors did not differ between subjects with IgA titers above and below the 95th percentile cutoff. However, in multivariate analyses, models incorporating both IgA titers and a classic risk factor such as obesity, hypercholesterolemia, or smoking predicted risk more effectively than single-parameter models. For example, the odds ratio for AMI among subjects with the highest IgA titers plus hypercholesterolemia was greater than the product of individual risks associated with these high IgA titers and with hypercholesterolemia.

CONCLUSIONS

Interactions with classic risk factors (ie, obesity, hypercholesterolemia, and smoking), increased the predictive value of C pneumoniae IgA antibody titers in determining risk of AMI.

Lack of association between Chlamydia pneumoniae seropositivity and aortic atherosclerotic plaques: a population-based transesophageal echocardiographic study

OBJECTIVES

The objective of this study was to examine the relationship between Chlamydia pneumoniae seropositivity and aortic atherosclerotic plaques in the general population.

BACKGROUND

Seroepidemiologic studies suggest that C pneumoniae infection plays a role in the pathogenesis of atherosclerosis.

METHODS

Transesophageal echocardiography was performed in 385 subjects (median age 66 years, range 51 to 101 years; 53% men), a sample of the Olmsted County (Minnesota) population. The association between C pneumoniae immunoglobulin (Ig) G antibody titers and aortic atherosclerotic plaques was examined.

RESULTS

Chlamydia pneumoniae IgG antibodies (titers >or=1:16) were detected in 287 subjects (74.5%): low titers (1:16 to 1:32) in 58 (15.1%), intermediate titers (1:64 to 1:128) in 144 (37.4%), and high titers (>or=1:256) in 85 subjects (22.1%). Antibody titers were not associated with the presence of aortic plaques after adjustment for age, gender, and smoking status (p = 0.64). Compared with titers <1:16, the adjusted odds ratios for aortic plaques were 1.46 (95% confidence interval [CI] 0.63 to 3.42) for low titers, 1.32 (95% CI 0.68 to 2.55) for intermediate titers, and 0.94 (95% CI 0.42 to 2.07) for high titers. Among the subgroup with plaques, antibody titers were not associated with the presence of plaques >or=4 mm thick (p = 0.99), plaques >or=6 mm (p = 0.49), or mobile debris (p = 0.71), after adjustment for age and smoking.

CONCLUSIONS

Chlamydia pneumoniae IgG antibody titers are not associated with the presence or severity of aortic atherosclerosis in the general population. These observations do not support a role for C pneumoniae infection in the initiation or progression of atherosclerosis.

Role of antibiotics for the prevention of cardiovascular disease

OBJECTIVE

To evaluate the data regarding the use of antibiotic therapy for the prevention of cardiovascular events.

DATA SOURCES

Pertinent literature was identified through a MEDLINE search (1966-September 2001) and through other secondary literature databases and/or bibliographies of pertinent articles.

DATA SYNTHESIS

Cardiovascular disease is a common cause of morbidity and mortality among the general population, with well-defined risk factors (e.g., diabetes, hypertension, hyperlipidemia, cigarette smoking, genetic predisposition). Clinical data evaluating the association between the aforementioned risk factors and the development of atherosclerosis and subsequent cardiovascular disease are substantial; however, these risk factors may only partially explain the high prevalence of cardiovascular disease. The presence of Chlamydia pneumoniae within atherosclerotic lesions has been documented and may be an additional risk factor for the development and progression of cardiovascular disease.

CONCLUSIONS

The results of primary and secondary prevention trials have shown conflicting evidence with regard to the beneficial effects of antibiotic therapy to reduce cardiovascular events. Currently, the lack of certainty in published data does not support the use of antibiotics for the prevention of cardiovascular disease. Clinicians should continue to emphasize interventions proven to reduce adverse cardiovascular events such as smoking cessation, reduction of hyperlipidemia, and control of hypertension.

Induction of proinflammatory cytokines in human lung epithelial cells during Chlamydia pneumoniae infection

Chlamydia pneumoniae is an obligate intracellular human pathogen that causes acute respiratory diseases such as pneumonia and bronchitis. Previous studies have established that C. pneumoniae can induce cytokines in mouse and/or human cells, but little information is available on the cytokine response of respiratory epithelial cells, a first line of infection. In this study, heparin treatment of C. pneumoniae significantly reduced its ability to induce interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) mRNA in human lung carcinoma cells, indicating that cytadherence is an important early stimulus for induction of proinflammatory mediators. Although the IL-8, gamma interferon, and TNF-alpha message was consistently induced by infection of A549 cells not treated with heparin, only an elevation of IL-8 protein was detected in A549 supernatants. A549 IL-beta and IL-6 mRNA and supernatant protein profiles were not significantly changed by infection. Heat or UV inactivation of C. pneumoniae only partially reduced the cytokine response, and inhibition of C. pneumoniae protein or DNA synthesis did not affect its ability to induce cytokine gene expression. To prevent stress-induced cytokine release by the A549 cells, centrifugation was not utilized for infection experiments. These experiments establish the importance of cytadherence in cytokine release by cells of respiratory epithelial origin and suggest that further work in the area of cytokine mediators is warranted to gain valuable pathogenic and therapeutic insights.

Chlamydia pneumoniae and multiple infections in the aorta contribute to atherosclerosis

Our previous study on herpesvirus infection including Herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV), cytomegalovirus (CMV) and atherosclerosis revealed that the prevalence of herpesvirus is higher in atherosclerotic aorta than in non-atherosclerotic aorta. Infections with two or three forms of the virus have been found only in atherosclerotic aorta. In our current study, we examined both Chlamydia pneumoniae and Chlamydia trachomatis in herpesvirus-infected aortic tissues, by means of immunohistochemistry, polymerase chain reaction, Southern hybridization, in situ hybridization, electron microscopy and electron-microscopic immunohistochemistry. In particular, the bacteria were found in atherosclerotic lesions. In atherosclerotic aorta, 40% of tissues examined were positive for C. pneumoniae in contrast to absence of this bacteria in non-atherosclerotic aorta. Elementary bodies of C. pneumoniae were found in macrophage-like cells in the intima of atherosclerotic aorta by electron microscopy. Chlamydia trachomatis was not found in both atherosclerotic and non-atherosclerotic aorta. Our findings suggest that multiple infections in aortic tissue contribute to the development of atherosclerosis. Furthermore, the absence of C. pneumoniae compared to herpesviruses in normal arterial tissue suggests that C. pneumoniae is specific for atherosclerotic lesions. In contrast to 'abortive infection' of viruses in arteries, C. pneumoniae infection was demonstrated in macrophages by electron microscopy and electron-microscopic immunohistochemistry in atherosclerotic lesion. Chlamydia pneumoniae may be the most important pathogen related to the development of atherosclerosis.

Does infection with Chlamydia pneumoniae and/or Helicobacter pylori increase the expression of endothelial cell adhesion molecules in humans?

OBJECTIVE

To investigate if Chlamydia pneumoniae and/or Helicobacter pylori seropositivity is associated with elevated levels of soluble endothelial cell adhesion molecules (sCAMs) as markers of atherosclerotic activity.

METHODS

Immunoglobulin A (IgA) and IgG antibodies to the two bacteria, soluble intercellular cell adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin were measured in coronary heart disease (CHD) patients (n = 193) and age- and sex-matched controls (n = 193). Two different serological methods were used for the detection of Chlamydia antibodies: Labsystems microimmunofluorescence to detect species-specific C. pneumoniae antibodies and Medac's recombinant enzyme-linked immunosorbent assay to detect genus-specific lipopolysaccharide antibodies.

RESULTS

The concentrations of sICAM-1 and E-selectin were higher in CHD patients with positive vs. negative Chlamydia lipopolysaccharide IgA (P = 0.044 for both). H. pylori antibodies alone did not predict raised levels of sCAMs, but in CHD patients sICAM-1 was increased with IgA seropositivity to both bacteria compared to double seronegativity (P = 0.034). Concentrations of sVCAM-1 were elevated in CHD patients with double IgA seropositivity compared to those with Chlamydia lipopolysaccharide IgA seropositivity alone (P = 0.018).

CONCLUSION

Our results may indicate that C. pneumoniae contributes to increased inflammation in CHD, and that this contribution is even more pronounced when present in combination with H. pylori IgA antibodies.

Role of infection in atherosclerosis and coronary artery disease: a new therapeutic target?

There is growing evidence that inflammatory processes may be involved in the development of atherosclerosis and its complications. Viral and bacterial pathogens have been implicated as possible causative factors in the pathogenesis of coronary artery disease and postangioplasty restenosis. Antibiotic trials have been completed examining which treatment of infection can prevent the complications of coronary artery disease. In high-risk patients, the results of these most recent studies have not revealed any benefit of treatment.

Detection of Helicobacter pylori specific DNA in human atheromatous coronary arteries and its association to prior myocardial infarction and unstable angina

BACKGROUND

Chronic infections have been proposed to play a role in the aetiology or progression of atherosclerotic plaques. Increased risk of coronary artery disease has been suggested in patients seropositive for Helicobacter pylori.

AIM

To analyse coronary specimens in patients with severe (coronary artery disease) for Helicobacter pylori specific DNA.

PATIENTS AND METHODS

Atherosclerotic plaques were obtained in 46 consecutive patients (9 female, 37 male, mean age 62.7+/-9.17 years) during coronary bypass procedures. Serum was analysed for IgG -/cagA-antibodies specific for Helicobacter pylori. Polymerase chain reaction and sequence analysis were used to identify bacterial DNA. Coronary artery biopsies from 19 autopsies without coronary artery disease were examined as a control group.

RESULTS

Of the 46 coronary artery disease patients, 32 (69.6%) were Helicobacter pylori seropositive. Positive results for Helicobacter pylori DNA showed 18 seropositive and 4 seronegative (with anamnesis of eradication therapy). A total of 22 patients (47.8%) of the coronary artery disease group but none of controls revealed positive DNA. In the coronary artery disease group, a correlation between DNA presence and prior myocardial infarction (p=0.008) and unstable angina (p<0.001) was found.

CONCLUSION

Identification of DNA in atherosclerotic plaques of patients with severe coronary artery disease supports the hypothesis that Helicobacter pylori infection may influence the development of atherosclerosis. Our results may indicate an direct involvement of Helicobacter pylori in the progression and instability of plaques in these patients.

Review of evidence for a connection between Chlamydia pneumoniae and atherosclerotic disease

BACKGROUND

Established risk factors account for no more than 50% of coronary artery disease cases; therefore, the search continues for other modifiable risk factors. In recent years, there has been renewed interest in the infectious theory of atherosclerosis. Chlamydia pneumoniae has been implicated as a potential cause of atherosclerotic disease.

OBJECTIVE

This review discusses possible mechanisms of C pneumoniae involvement in atherosclerosis, summarizes the case-control studies and antibiotic trials completed, and identifies remaining questions about future therapy.

METHODS

Published data were identified by a MEDLINE search of the English-language literature from 1966 through 2001 using the terms Chlamydia, atherosclerosis, and coronary artery disease. Relevant conference presentations and book chapters were also included.

RESULTS

C pneumoniae antibodies are found in approximately 50% of middle-aged adults world-wide. These antibodies have been detected in atherosclerotic tissue by various methods, including microimmunofluorescence, and several studies have linked high antibody titers with increased risk of cardiovascular events. A few possible mechanisms for this perceived increase in risk have been proposed, such as induction of atheroma through damage to the endothelium, expression of procoagulant factor leading to thrombus formation, and production of cytokines resulting in increased inflammatory response. Results of animal studies suggest that early antibiotic treatment may reduce cardiovascular risk, but the first human studies have not produced conclusive results.

CONCLUSIONS

Although a connection has been suggested, the precise mechanism by which C pneumoniae affects atherosclerosis has not yet been identified. Large-scale trials are needed to determine whether eradication of C pneumoniae reduces the incidence of cardiovascular events in humans.

Antibiotics against Chlamydia pneumoniae and prognosis after acute myocardial infarction

BACKGROUND

There is mounting pathologic and immunologic evidence that Chlamydia pneumoniae plays a role in the atherogenic pathway. However, very few clinical studies have supported these findings.

METHODS

Using the administrative data of all patients > or =65 years of age who had an acute myocardial infarction (AMI) in Quebec between 1991 and 1995 (n = 26,195), we studied the relationship between the intake of antichlamydial antibiotics and post-AMI prognosis. Three groups were compared: patients exposed to (1) antichlamydial antibiotics, (2) sulfa-derivative antibiotics, to which C pneumoniae is not sensitive, and (3) neither of the above classes of antibiotics. Two periods of antibiotic exposure were explored: (1) during the first 3 months after AMI and (2) during the 6 months before AMI.

RESULTS

Patients in the 3 exposure groups were similar except for a slightly lower proportion of men in the sulfa-derivative antibiotics group. Among all patients who were exposed during the 3 months after AMI and who survived at least 3 months, the 1-year mortality rate was similar across the 3 groups (10.1%, 11.1%, and 10.4% for the antichlamydial, sulfa-derivative, and nonexposed group, respectively) but favored the antichlamydial group at 2 years (15.9%, 23.0%, and 20.0%). In adjusted survival analysis, patients in the sulfa-derivative and nonexposed groups were slightly more likely to die than patients in the antichlamydial group (relative risk [RR], 1.38; 95% confidence interval [CI], 1.04 to 1.82 and 1.29; 95% CI, 1.05 to 1.59, respectively). Among individuals treated during the 6 months before AMI, the adjusted risk of dying was similar in the sulfa-derivative and nonexposed groups compared with the antichlamydial group (RR 1.03, 95% CI 0.90 to 1.18 and 1.08, 95% CI 0.99 to 1.19, respectively).

CONCLUSIONS

Exposure to antichlamydial antibiotics during the 3 months after AMI is associated with a small survival benefit, whereas exposure during the 6 months before AMI does not affect survival.

No causal association between inflammation and Chlamydia pneumoniae in patients with chronic ischemic arterial disease

The C-reactive protein, Chlamydia-specific IgG antibody, and fibrinogen were assayed in the serum of 159 patients with arterial disease (the arterial group) and 203 patients with heart valve prostheses (the valvular group) and no demonstrable coronary disease. In the arterial group, the Chlamydia pneumoniae antibody was > or = 1:32 for 67.3% (107/159) of the patients, the C-reactive protein was elevated in 41.5% (66/159), and the fibrinogen was elevated in 27.7% (44/159). In the valvular group, the C. pneumoniae antibody was > or = 1:32 for 59.1% (120/203) of the patients; the C-reactive protein was elevated in 34.0% (69/203), and the fibrinogen was elevated in 17.2% (35/203). Of 107 patients in the arterial group with C. pneumoniae titers > or = 1:32, only 26 (24.3%) had elevated fibrinogen (426 +/- 29 mg/dL) and 44 (41.1%) had elevated C-reactive protein (1.06 +/- 0.52 mg/dL). Similarly, of the 120 patients in the valvular group with C. pneumoniae titers > or = 1:32, 17 (14.2%) had elevated fibrinogen (409 +/- 29 mg/dL) and 34 had elevated C-reactive protein (0.99 +/- 1.1 mg/dL). Correlated poorly was C. pneumoniae with C-reactive protein and fibrinogen levels. Only the fibrinogen level could be discriminated between the arterial and the valvular group. These results suggest that no causal association exists between inflammation and C. pneumoniae. A highly significant correlation between C-reactive protein and fibrinogen levels was found.

Chlamydia pneumoniae and atherosclerosis: critical assessment of diagnostic methods and relevance to treatment studies

A number of studies have found that inflammation of the vessel wall plays an essential role in both the initiation and progression of atherosclerosis and erosion and fissure and the eventual rupture of plaques. Chlamydia pneumoniae is one of the infectious agents that have been investigated as possible causes of this inflammation. Initial studies of the association of C. pneumoniae and cardiovascular disease (CVD) were seroepidemiologic, and these were followed by studies in which the organism was identified in vascular tissue from patients with CVD by electron microscopy, PCR and immunocytochemical staining (ICC). C. pneumoniae has also been isolated by culture from vascular tissue in a small number patients. However, no single serologic, PCR, or ICC assay has been used consistently across all studies. The assays used are also not standardized. Recent studies of serologic and PCR assays for diagnosis of C. pneumoniae infection have suggested that there may be substantial interlaboratory variation in the performance of these tests. It now appears that some of the inconsistency of results from study to study may be due, in part, to lack of standardized methods. Although initial seroepidemiologic studies demonstrated a significantly increased risk of adverse cardiac outcome in patients who were seropositive, subsequent prospective studies found either small or no increased risk. In addition to the lack of consistent serologic criteria, recent evaluations have demonstrated inherent problems with performance of the most widely used serologic methods. Most importantly, we do not have a reliable serologic marker for chronic or persistent C. pneumoniae infection.

Secondary prevention of coronary artery disease with antimicrobials: current status and future directions

Over the past several decades, coronary artery disease (CAD) has become the major health problem in the Western world with more than 50% of deaths attributed to its complications. The exact causes of atherosclerosis are not clearly known, although multiple risk factors (e.g. hypertension, hyperlipidemia, diabetes mellitus, family history, and smoking) have been well described. However, these risk factors account for only about 50% of the total risk of CAD. Consequently, an ongoing search is under way to discover new risk factors for atherosclerosis as well as the basic underlying causes of progression. Although the evidence is not yet definitive, recent studies have shown that chronic infection by such bacterial organisms as Chlamydia pneumoniae, Helicobacter pylori, and a variety of dental pathogens may play a causative role in atherosclerosis. If this is true, then antimicrobial therapy may be helpful in the secondary prevention of CAD. Indeed, several small studies have already been completed testing this hypothesis. This article reviews the evidence associating these bacterial pathogens to CAD and presently available information regarding the use of antibiotics in the setting. At present, most studies evaluating the potential efficacy antimicrobials in the secondary prevention of CAD have tested the use of macrolide antibodies. Although several small preliminary studies have reported promising results favoring a clinical benefit from even short (<3 months) courses of antimicrobial therapy, the first large clinical trial, the Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders (WIZARD) study, did not show a statistically significant beneficial effect of a 3 month course of azithromycin over placebo by the end of up to 4 years follow-up. However, a statistically significant (p = 0.03) 33% reduction in death and myocardial infarction was found at 6 months, 3 months after the discontinuation of antibiotics. This robust clinical benefit, however, was not sustained over the ensuing 3.5 years of follow-up. These disappointing long-term outcomes of short-term therapy with antimicrobials may be explained by the recently discovered difficulty found in eradicating chronic vascular infections such as C. pneumoniae. It remains possible that longer term antimicrobial therapy or short-term use of more potent single agents or combinations, capable of effectively eradicating the offending organisms might provide added clinical benefit in the fight against CAD. Further studies are ongoing or planned to evaluate this potential. In the meantime, it is not presently recommended that antimicrobials be routinely prescribed for the secondary prevention of CAD.

Relation of antibiotic use to risk of myocardial infarction in the general population

There are conflicting reports of an association between Chlamydia pneumoniae (C. pneumoniae) infection and coronary artery disease (CAD); randomized trials of antibiotics for the secondary prevention of CAD are currently underway. Physicians may be tempted to believe that their choice of antibiotic class in treating any infection may alter the risk of CAD. Our objective was to determine if the use of antibiotics with antichlamydial activity in the general population reduces the risk of myocardial infarction. A healthcare claims database with 354,258 patients with continuous health and pharmacy coverage for at least 2 years between January 1, 1991 and December 31, 1997 was used for the analyses. Hazard ratios were derived from proportional hazards models with time-dependent covariates, relating antibiotic prescription to first claim related to incident first myocardial infarction during the observation period, adjusting for previous CAD, age, sex, diabetes, hypertension, hyperlipidemia, and chronic obstructive pulmonary disease. There were a total of 1,684,091 person-years of observation and 16,139 incident myocardial infarctions. The adjusted hazard ratios were 1.10 (95% confidence intervals [CI] 1.04 to 1.16) for macrolides, 1.20 (95% CI 1.13 to 1.26) for quinolones, 1.10 (95% CI 0.96 to 1.21) for cephalosporins, 1.00 (95% CI 0.96 to 1.06) for tetracyclines, 1.01 (95% CI 0.96 to 1.06) for penicillins, and 1.13 (95% CI 0.98 to 1.30) for trimetroprim-sulfamethoxazole. The hazard ratios for individual antibiotics with activity against C. pneumoniae within each group were similar. Use of antibiotics with activity against C. pneumoniae does not reduce the risk of myocardial infarction in the general population.

Relation of Chlamydia pneumoniae infection in Taiwan to angiographically demonstrated coronary artery disease and to the presence of acute myocardial infarction or unstable angina pectoris

Reports of the association of Chlamydia pneumoniae (C. pneumoniae) infection with coronary artery disease (CAD) are scarce in the Oriental population. We therefore conducted a case-control study to explore this issue in Taiwan. There were 242 consecutive subjects (166 men and 76 women) who underwent cardiac catheterization at the National Taiwan University Hospital Cardiac Catheterization Laboratory. Patients with CAD (n = 156) had > or = 1 coronary artery lesion of > 50% diameter stenosis on angiography. Controls (n = 86) had no demonstrable CAD angiographically. Antibodies to C. pneumoniae were tested by using an enzyme-linked immunosorbent assay. The prevalence of antibodies to C. pneumoniae was as follows: immunoglobulin-G (IgG), 50% (122 of 242 patients); immunoglobulin-A (IgA), 72% (176 of 242 patients); and either IgG or IgA, 79% (192 of 242 patients ). The odds ratio (OR) for CAD with either IgG or IgA was 1.4 (95% confidence interval [CI] 0.7 to 2.7, p = 0.31). After adjusting for the known CAD risk factors, the OR decreased to 0.8 (95% CI 0.3 to 2.1, p = 0.60). The OR for unstable angina or acute myocardial infarction with the presence of either IgG or IgA was 0.5 (95% CI 0.2 to 1.1, p = 0.08) and 0.4 ( 95% CI 0.1 to 1.0, p = 0.049) after adjusting for other risk factors. These results suggest a high prevalence of C. pneumoniae infection in Taiwan. However, C. pneumoniae infection is not associated with angiographically documented CAD, and, in contrast, is a negative predictor for the development of acute coronary syndromes.

Absence of Chlamydia pneumoniae in surgical specimens of coronary and carotid arteries by polymerase chain reaction

PURPOSE

Several recent articles indicate the renewed interest that Chlamydia pneumoniae is associated with and contributes to arterial diseases. Associations have been established for coronary arteries, carotid arteries and abdominal aortic aneurysms by serological studies, immunofluorescence and DNA-specific testing. The purpose of this study was to determine the presence of C. pneumoniae in coronary artery plaques, carotid artery plaques and old vein grafts that were harvested at the time of surgery.

METHODS AND MATERIALS

Interventions were carried out on patients with carotid artery disease and coronary disease based upon their anatomic findings and symptomatology. Plaques were removed from the carotid arteries with standard endarterectomy techniques. The coronary plaques were removed utilizing blunt dissection to peel the plaque from the coronary artery. Old vein grafts were harvested during repeat surgery by excising the vein grafts. The tissue specimens were analyzed by polymerase chain reaction (PCR).

RESULTS

Ninety-nine specimens from 68 consecutive patients with advanced coronary atherosclerosis with or without cerebrovascular disease were analyzed. We failed to find C. pneumoniae in any of the vascular tissue.

CONCLUSIONS

A large cooperative study involving surgical specimen analysis is needed to assess the role of C. pneumoniae in the etiology of atherosclerosis.

The role of risk factors in the development of atherosclerosis

Our understanding of risk factors for atherogenesis has changed significantly over the last decade. In addition to better grasp of the mechanism of action of the "classic" (causal) risk factors, a number of potentially important new factors has emerged. In this review we briefly summarize the evidence of the relation between atherosclerosis and the currently recognized causal risk factors, namely, age, smoking, LDL cholesterol, HDL cholesterol, hypertension, and diabetes. More emphasis has been put on description of the emerging entities such as atherogenic profile of plasma lipoproteins with discussion of LDL and HDL subclasses, Lp(a), homocysteine, and, last but not least, on the role of infection and inflammation in atherogenesis. Whenever possible, we tried to summarize the relevant lines of evidence such as epidemiological, pathological, genetic, and clinical trial data linking the specific factor with atherosclerosis.

Antibiotic use and risk of ischemic stroke in the elderly

PURPOSE

To determine whether treating infections with antibiotics that have antichlamydial activity decreases the risk of ischemic stroke in the elderly.

SUBJECTS

We analyzed data from 199 553 subjects 65 years and older in a health care claims database who had continuous health and pharmacy coverage for at least 2 years between January 1, 1991, and September 30, 1997. Using proportional hazards models with time-dependent covariates for prior antibiotic prescription and adjusting for cardiovascular risk factors, we determined the associations between antibiotic use and first claim for ischemic stroke (n = 7,335) during the observation period.

RESULTS

Rates of stroke (per 1,000 person-years) were 6.64 for macrolides, 9.27 for quinolones, 7.49 for tetracyclines, 6.88 for penicillins, 7.97 for cephalosporins, 8.58 for trimethoprim-sulfamethoxazole, and 7.29 for subjects with no antibiotic claims. The adjusted hazard ratios (HR) were 0.94 (95% confidence interval [CI]: 0.87 to 1.01) for macrolides, 1.04 (95% CI: 0.91 to 1.18) for tetracyclines, 1.02 (95% CI: 0.95 to 1.08) for penicillins, and 1.00 (95% CI: 0.82 to 1.22) for trimethoprim-sulfamethoxazole. Subjects with claims for quinolone antibiotics (HR = 1.17; 95% CI: 1.09 to 1.26) and cephalosporins (HR = 1.09; 95% CI: 1.02 to 1.16) had a slightly higher risk of stroke.

CONCLUSION

Exposures to short courses of antibiotics are not associated with lower risk of ischemic stroke in patients aged 65 years and older.

Demonstration of Chlamydia pneumoniae in atherosclerotic arteries from various vascular regions

Chlamydia pneumoniae (CP) has been reported to be a pathogenic agent in the mechanism leading to atherosclerosis. The majority of available data is focused mainly on coronary artery disease whereas the distribution of CP in different areas, associated with atherosclerotic disorders, has not been completely clarified. In this study we investigated the presence of CP in atheromasic plaques from five different vascular areas (basilary artery, coronary artery, thoracic aorta, abdominal aorta, renal arteries) using nested polymerase chain reaction (PCR) and immunohistochemical staining (IHC), in order to establish the putative association of CP with atherosclerotic disease. The same atheromasic plaques were also tested for the presence of Helicobacter pylori (HP) and cytomegalovirus (CMV), other putative agents of atherosclerosis, using a nested PCR technique. Our data indicate that the presence of CP can be demonstrated in 100% of patients tested, considering globally the five areas of analysis. On the other hand the presence of HP has been demonstrated in four out of 18 patients (22.2%), and CMV only in three out of 18 (16.6%). Our results strongly suggest an association between CP and atherosclerosis and highlight the need for the detection of CP in multiple vascular areas of the same patient.

Indicators of infection with Chlamydia pneumoniae are associated with expansion of abdominal aortic aneurysms

PURPOSE

Chlamydia Pneumoniae has been shown to be associated with atherosclerosis, myocardial infarction, and abdominal aortic aneurysms (AAAs). The possible association between AAA expansion and C pneumoniae infection was therefore assessed.

METHODS

Blood samples were taken from patients with an AAA that was considered for surgical repair after having been diagnosed by means of the Chichester aneurysm screening program (UK) as having an initially infrarenal aortic diameter of 3.0 to 5.9 cm. The patients were examined prospectively for as long as 11.5 years (mean, 4.1 years) with ultrasound scanning. Of 110 patients considered for surgery, 90 men and 10 women had blood samples taken. Their IgG and IgA antibodies against C pneumoniae were measured by means of a microimmunofluorescence test. Unpaired t tests, multiple linear regression analyses, and logistic regression analyses were used for statistical analysis.

RESULTS

A total of 44% (95% CI, 31%-55%) of the men with an AAA had an IgA titer of 64 or more, an IgG titer of 128 or more, or both, compared with 10% of the women with an AAA (OR = 7.2; 95% CI, 1.05-160.8). A titer of IgG of 128 or more was significantly associated with higher expansion (5.3 vs 2.6 mm per year), even after adjustment for initial AAA size and age. A significant positive correlation between both IgA and IgG titers and mean annual expansion was observed (r = 0.28; 95% CI, 0.05-0.49; and r = 0.45; 95% CI, 0.24-0.62, respectively), persisting after adjusting for initial AAA size and age. An IgG titer of 128 or more was present significantly more often in cases with an expansion greater than 1 cm annually (adjusted OR = 12.6; 95% CI, 1.37-293).

CONCLUSION

A high proportion of men with an AAA has signs of infection with C pneumoniae. The progression of their AAAs was positively correlated with the presence of indicators of C pneumoniae infection.

Antibodies against Chlamydia pneumoniae predict the need for elective surgical intervention on small abdominal aortic aneurysms

OBJECTIVE

to compare the ability of two independent Chlamydia pneumoniae antibody tests to predict need for small abdominal aortic aneurysm (AAA) repair.

PATIENTS AND METHODS

annual scans were offered to 149 screening diagnosed small AAA (<5 cm). Serum samples were collected for measuring IgA and IgG-antibodies to C. pneumoniae by microimmunofluorescence (MIF) test and the new ELISA (Labsystems).

RESULTS

a significant concordance was found between MIF and ELISA titres with Kappa values of 0.29 for S-IgA and 0.42 for S-IgG. IgG antibodies measured by ELISA were most predictive for cases expanding operation recommendable sizes with a sensitivity and specificity of 80% and 66%, respectively.

CONCLUSION

the simpler EIA has a high correlation with the MIF test and both were predictive for the natural history of AAA. Chlamydia antibody test may be used to identify individuals who might benefit from follow-up and anti-chlamydia treatment.

Chlamydia pneumoniae serology: importance of methodology in patients with coronary heart disease and healthy individuals

Most publications on the relationship between infection with Chlamydia pneumoniae and coronary heart disease (CHD) propose an association, but negative studies are also reported. Seroepidemiological studies vary in the use of different serological methods, different cutoff limits, different sampling times in relation to acute cardiac events, and different clinical stages of CHD. We wanted to compare three different commercially available methods for measuring Chlamydia antibodies to see how the choice of method influenced the prevalence of seropositive individuals in CHD patients and in healthy individuals and to see if sampling time in relation to an acute cardiac event or the stage of atherothrombotic disease influenced the results. Blood samples from 197 CHD patients and 197 individually matched healthy control individuals were tested at baseline and after 6 months; the mean age was 55 years in both groups, and 18% were women. Among the CHD patients, 166 were included at a median of 16 days after an acute cardiac event and 31 had chronic disease with the latest acute event being >3 months earlier. The difference in prevalence of antibodies between the CHD patients and the healthy controls was significant when Chlamydia lipopolysaccharide antibodies were measured, while no significant differences between the study groups were observed by the two methods detecting Chlamydia pneumoniae major outer membrane protein antibodies. The number of seropositive individuals was quite similar at inclusion and 6 months later, and no significant differences were observed between patients with a recent cardiac event and those with a more remote cardiac event. We conclude that the choice of serological method is of major importance when evaluating a possible relationship between C. pneumoniae and CHD.

Association of seropositivity for antibody to Chlamydia-specific lipopolysaccharide and coronary artery disease in Japanese men

Recent studies suggest an association between Chlamydia pneumoniae infection and coronary artery disease (CAD). To examine this relationship in Japanese men, serum IgA and IgG antibodies to Chlamydia-specific lipopolysaccharide were measured by enzyme-linked immunosorbent assay in 507 patients with CAD and 200 age-matched controls. CAD patients were divided into (1) 269 patients with myocardial infarction (MI) and (2) 238 patients with chronic coronary heart disease (CCHD). Compared with the control group, the CAD group did not differ in the prevalences of both antibodies (IgA: 23.7 vs 18.0%, p=0.10; IgG: 52.7 vs 51.0%, p=0.6). The index of IgG antibody was not significantly different between CAD and control groups (median 1.19 vs 1.18, p=0.3), whereas the index of IgA antibody was significantly higher in CAD than control group (median 0.60 vs 0.46, p<0.0001). Compared with the control group, the MI group had a significantly higher prevalence of IgA antibody (28.6 vs 18.0%, p=0.007); however, there was no difference in the prevalence of IgG antibody (58.0 vs 51.0%, p=0.13). The CCHD group did not differ in the prevalences of both antibodies (IgA: 18.1 vs 18.0%, p=0.9; IgG: 45.6 vs 51.0%, p=0.2). After the adjustment for coronary risk factors, odds ratios (ORs) of seropositive antibodies for CAD were 1.59 [95% confidence interval (CI): 0.88-2.87, p=0.12] for IgA seropositivity and 0.92 (95%CI: 0.58-1.47, p=0.7) for IgG seropositivity in all cases. In the MI and control groups, ORs of seropositive antibodies for MI were 2.67 (95%CI: 1.32-5.38, p=0.007) for IgA seropositivity, and 1.36 (95%CI: 0.79-2.36, p=0.2) for IgG seropositivity. This study discovered that IgA antibody to Chlamydia was significantly associated with CAD, especially with MI, in Japanese Men and the findings suggest that chronic infection of Chlamydia may be linked to the pathogenesis of MI.

Comparison of a new commercial EIA kit and the microimmunofluorescence technique for the determination of IgG and IgA antibodies to Chlamydia pneumoniae

Chlamydia pneumoniae infection is often diagnosed by analyzing specific antibodies to C. pneumoniae in sera. The method which has been used as the reference method, or "gold standard", the microimmunofluorescence test (MIF), demands a high level of experience for proper interpretation. A number of commercial enzyme immunoassay (EIA) tests have been introduced to the market in the past few years. These provide objective reading of titers, but are genus specific and not species specific. The latest EIA introduced, LabSystems EIA for C. pneumoniae, was investigated using several groups of clinically relevant patient sera in a comparison with MIF. It was found that the LabSystems EIA did not discriminate between antibodies to C. trachomatis and C. pneumoniae when tested with sera containing high titers of C. trachomatis antibodies. The correlation between C. pneumoniae EIA and MIF IgG and IgA titers was, however, good in the patient groups not having a high background of C. trachomatis antibodies: hypertensives, n= 199 and patients with chronic C. pneumoniae infections and ischaemic heart disease, n=33. In conclusion, the LabSystems EIA is a method which can be useful for screening populations with low prevalences of C. trachomatis/C. psittaci infection for antibodies to C. pneumoniae. It cannot replace the MIF test due to the lack of discrimination between different chlamydial antibody types.

Possible role of chronic infection with Chlamydia pneumoniae in Japanese patients with acute myocardial infarction

Chlamydia pneumoniae, a common human respiratory pathogen, has been implicated in the pathogenesis of coronary heart diseases (CHD) in several seroepidemiological studies. The present case-control study investigated the relation between serologic evidence of C. pneumoniae infection and CHD in a Japanese population. Two groups of cases were enrolled: 26 patients with acute myocardial infarction (AMI) and 46 patients with effort angina pectoris (e-AP). Their data were compared with 58 age-matched healthy controls and also compared with 53 patients with vasospastic angina (VSA) as pathological control subjects. Anti-C. pneumoniae specific IgA and IgG antibody titers were measured by enzyme-linked immunosorbent assay (ELISA). The mean indices of IgG-type antibody in AMI and e-AP were not significantly different from those in either the normal controls or VSA group. On the other hand, the mean indices of IgA-type antibody in AMI were significantly higher than in the normal controls (1.39+/-0.83 in AMI vs 0.84+/-0.58 in controls, p<0.001) and VSA (1.39+/-0.83 in AMI vs 1.05+/-0.61 in VSA, p<0.05) group. However, the differences in the IgA titers in the e-AP group compared with the normal controls did not reach a significant level. The odds ratio associated with the seropositivity of IgA for AMI against the normal controls was 3.89 (95% confidence interval (CI): 1.16-13.10) and that against VSA was 6.90 (95% CI: 1.73-27.52) after adjustment for risk factors for CHD and/or age, sex and smoking status. In 6 patients the elevated IgA titers were sustained even at 3 months after the episode of AMI. These results suggest that seropositivity for IgA-type antibody against C. pneumoniae may be a significant risk factor for the development of AMI. The possible mechanisms include chronic inflammation in the coronary artery due to persistent C. pneumoniae infection.