Chlamydia pneumoniae infection in Slovenian patients with diffuse coronary artery disease

Chlamydia pneumoniae (CP) infection might be involved in the pathogenesis of various forms of coronary artery disease (CAD), but there are no data about diffuse CAD with clinical picture of stable angina pectoris. Authors in a prospective study determined serum CP antibody levels (with MIF test) of 71 patients with coronarographically proven diffuse CAD and compared them to the age matched control group of the healthy Slovenian population. After azithromycin treatment in patients with chronic CP infection or reinfection, the CP antibody levels were determined again. A high percentage of chronic infection with CP was demonstrated (83.1%), and almost half (46.5%) of patients with diffuse CAD had reinfection or reactivation of chronic infection. A significantly higher prevalence of chronic CP infection was found in patients with diffuse CAD than in the healthy population (83.1% vs. 15.9%, p< 0.0001). After treatment with azithromycin, IgA seronegativity was achieved in 17.3%, in 23.1% the titer was lowered, however, in 57.7% of patients no change of antibody titers was found. In conclusion, a high prevalence of chronic infection with CP was found in patients with diffuse CAD. With azithromycin therapy, the eradication of chronic infection is difficult to achieve as well as to prove.

Association of Chlamydia pneumoniae antibody with the cholesterol-lowering effect of statins

To investigate the association between Chlamydia pneumoniae (C. pneumoniae) infection and atherosclerosis, we compared the effect of lipid-lowering drugs on carotid intima-media thickness (IMT) between patients who were positive and negative for C. pneumoniae antibodies. A total of 165 asymptomatic hypercholesterolemic patients were randomized to probucol (500 mg per day, n = 82) or pravastatin (10 mg per day, n = 83) and followed for 2 years. The 2-year change of IMT in the common carotid artery was the primary endpoint, while mean IMT change and major cardiovascular events were secondary endpoints. C. pneumoniae antibodies (IgA and IgG) were measured by enzyme-linked immunosorbent assay. The 50 patients without C. pneumoniae antibodies showed significant reduction of IMT progression (-19%), while no significant change of IMT was noted in the 115 antibody-positive patients (-6%). Significant inverse associations were found between the reduction of IMT progression and the C. pneumoniae IgA- and IgG-antibody index (P < 0.01 and 0.01, respectively). No significant differences in the reduction of serum total-cholesterol and LDL-cholesterol were found between antibody-positive and -negative patients. There was no significant difference of efficacy between probucol and pravastatin. These observations suggest that C. pneumoniae infection reduces the effect of lipid-lowering therapy on carotid atherosclerosis and that this organism may play a role in the progression of atherosclerosis.

The influence of comorbidity on the effect of levofloxacin treatment success of ambulatory respiratory tract infections

The influence of patient relevant parameters such as age, comorbidity, or duration of disease on the treatment success of levofloxacin for community-acquired respiratory tract infections (CARTI) has not been thoroughly elucidated. We therefore conducted a prospective cohort study of 9831 patients with CARTI in a clinical practice setting. The patients received 500 mg of levofloxacin once a day over a mean of seven days. Twenty-two attributes per patient were recorded before treatment initiation and after seven to fourteen days after start of treatment. Descriptive and explorative statistics such as the k-means and C4.5 algorithms were used to analyze the dataset. The overall success rate of levofloxacin therapy for CARTI was over 98%, side effects occurred in 1.6% of patients. Descriptive analysis revealed a weak correlation between parameters which significantly influence the course of disease, such as the number of comorbidities, the duration of infection before levofloxacin start, or the severity of symptoms and the treatment success. Explorative statistics yielded similar results. Two homogenous clusters, holding 34 and 45% of patients respectively, yielded the number of comorbid conditions and the duration of infection as main attributes negatively influencing treatment success. We therefore conclude, that the number of co-morbid conditions and the duration of infection before start of treatment as the strongest negative predictors for treatment success.

Assessment of plasma concentrations of doxycycline in budgerigars fed medicated seed or water

OBJECTIVE

To determine whether plasma doxycycline concentrations considered effective for treatment of avian chlamydiosis could be safely established and maintained in budgerigars via administration of doxycycline in water or seed.

DESIGN

Prospective study.

ANIMALS

68 healthy mature budgerigars.

PROCEDURE

In 14-day trials, plasma doxycycline concentrations were measured in budgerigars provided with water containing 0, 50, 100, 200, or 400 mg of doxycycline hyclate/L or a hulled seed diet containing 0, 100, 200, or 400 mg of doxycycline hyclate/kg. On the basis of these results, birds were fed seed containing 300 mg of doxycycline/kg for 42 days, and a control group received unmedicated seed. Blood samples for plasma doxycycline analysis were collected either in the morning on treatment days 4, 7 14, 21, 28, 35, and 42 or in the afternoon on days 12, 26, and 40. Birds were observed daily. On days 14, 28, and 42, physical and plasma biochemical variables, PCV, and total solids concentration were measured; cloacal specimens were obtained for bacteriologic and fungal culture.

RESULTS

During a 14-day period, treatment with water containing < or = 400 mg of doxycycline/L did not maintain plasma doxycycline concentrations of > or = 1 microg/mL, but seed containing 300 mg of doxycycline hyclate/kg maintained mean plasma doxycycline concentrations > 0.98 microg/mL for 42 days without notable adverse effects.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that hulled seed containing 300 mg of doxycycline hyclate/kg can safely establish and maintain plasma doxycycline concentrations that are considered adequate for treatment of chlamydiosis in adult nonbreeding budgerigars.

Outbreak and persistence of Chlamydia pneumoniae infection in an Italian family

We describe an outbreak of familial infection of Chlamydia pneumoniae, an etiological agent for respiratory tract infections. In a family member detection of C. pneumoniae on a pharyngeal swab by polymerase chain reaction was positive until four months after the onset of symptoms, despite a course of antibiotics known to be effective against Chlamydia species

In vivo release of oxytetracycline from a biodegradable controlled-release gel injected subcutaneously in Japanese quail (Coturnix coturnix japonica)

A long-acting, biodegradable, controlled-release formulation of oxytetracycline (CR-OTC) was evaluated in 18 adult Japanese quail (Coturnix coturnix japonica) following a single subcutaneous (s.c.) injection. Prior to characterizing the release of oxytetracycline (OTC) from the CR-OTC, the pharmacokinetic parameters of intravenously (i.v.) administered OTC were determined. Concentrations of free OTC were measured using a bioassay. The plasma concentration-time profile of OTC after a single i.v. injection at 20 mg/kg was best fit to an open two-compartmental model, with the following pharmacokinetic parameters: area under the curve (AUC) = 36.72 mg. h/L, terminal elimination half-life = 2.34 h, clearance (Cl) = 0.545 L/kg/h. Plasma [OTC] was >1.0 micro g/mL for at least 4 h following i.v. injection. The CR-OTC gel was well tolerated at a dosage of 1500 mg/kg s.c. Plasma [OTC] rose to >1.0 micro g/mL within 24 h; it remained >1.0 micro g/mL for at least 10 days in all birds sampled at that time point (n = 9) and for at least 18 days in two of nine birds. Using a deconvolution technique, it was determined that approximately 54.8% of the administered OTC was released from the CR-OTC over the 45-day observation period. This long-acting, biodegradable controlled-release OTC formulation may have potential for the treatment of chlamydophila infections and other OTC-sensitive bacteria in Japanese quail, however further studies are necessary to determine its safety and clinical application.

Hydroxymethylglutaryl coenzyme A reductase inhibition reduces Chlamydia pneumoniae-induced cell interaction and activation

BACKGROUND

Chlamydia pneumoniae stimulates chronic inflammation in vascular cells. Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) may have an ameliorating effect. We investigated possible mechanisms.

METHODS AND RESULTS

We infected human macrophages that in coculture spread infection to vascular smooth muscle cells (VSMCs). Cerivastatin (250 nmol/L) reduced VSMC infection by 33%. Western blotting made it apparent that VSMC infection resulted in increased cell membrane-associated RhoA and Rac1, implying increased prenylation of these proteins. This effect was blocked by statin but circumvented by mevalonate. Cytochrome C assays showed that infected VSMCs produced increased reactive oxygen species that was blocked by statin. Infection increased nuclear transcription factor-kappaB expression in VSMCs that was dose-dependently suppressed by statin. Infected VSMCs produced and released RANTES and MCP-1. Statin dose-dependently blocked this production both at the mRNA and protein levels. Mevalonate and M geranylgeranylpyrophosphate circumvented these effects.

CONCLUSIONS

C pneumoniae can be transmitted from macrophages to VSMCs. VSMCs showed an activation profile typical of atherosclerosis, namely Rac1 and RhoA prenylation, nuclear transcription factor-kappaB activation, reactive oxygen species production, and chemokine production. Statin reduces macrophage-mediated C pneumoniae-induced signaling and transmission.

[Chlamydia pneumoniae, atherosclerosis, and coronary disease]

There is an increasing body of evidence that links Chlamydia pneumoniae infections to atherosclerosis and the clinical complications of unstable angina, myocardial infarction and stroke. Several epidemiologic reports indicate an association between the presence and titer of Chlamydia pneumoniae antibodies and atherosclerosis and its complications. Other studies show the presence of Chlamydia pneumoniae, chlamydial antigens or nucleic acid in atherosclerotic plaques. Moreover, experimental studies present mechanisms by which Chlamydia pneumoniae may play a role in the induction of atherosclerosis and its complications. Finally, many studies have evaluated the effect of antibiotic treatment on cardiovascular events in humans. This article reviews all the aspects that link Chlamydia pneumoniae to atherosclerosis and its clinical manifestations.

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.

Chlamydia pneumoniae and coronary artery disease: the antibiotic trials

Parallel with the mounting evidence that atherosclerosis has a major inflammatory component, provoking agents that may initiate and drive this process have been sought. Infectious agents such as Chlamydia pneumoniae have been alleged to be activators of inflammation that may contribute to atherosclerosis and thus coronary artery disease (CAD) and its associated complications. A logical pneumoniae extension of this theory whether treating C pneumoniae infection with antibiotics and/or modulating inflammatory processes can affect CAD and its sequelae. This article discusses the potential role of C pneumoniae in atherosclerosis, its detection, and the rationale for antibiotics. Additionally, it summarizes the current randomized clinical trials of antichlamydial antibiotics in patients with CAD and draws conclusions based on the results.

Chlamydia pneumoniae infection in adult patients with persistent cough

Chlamydia pneumoniae is a frequent causative agent of acute respiratory disease. To assess whether C. pneumoniae plays a role in persistent cough, the prevalence of C. pneumoniae infection in adult patients with persistent cough was investigated. Nasopharyngeal swabs and serology samples from 366 adult patients with a persistent cough lasting in excess of 2 weeks and 106 control subjects were analysed for bacterial isolation and by PCR. C. pneumoniae was isolated from two patients and from none of the controls and was detected by PCR in 20 patients and one control. Serological evidence of acute C. pneumoniae infection was present in 24 patients but in none of the controls. Of these 20 patients who were positive by culture and/or PCR, three were still positive by PCR after 2 weeks of treatment with clarithromycin and symptoms either continued or relapsed. However, when patients were treated with clarithromycin for 5-6 weeks, their symptoms disappeared completely and the results of their cultures and/or PCR for C. pneumoniae became negative. These data suggest that C. pneumoniae infection may cause persistent cough in adults. Furthermore, these data also indicate that it may be necessary to eradicate the organism when C. pneumoniae is detected by culture and/or PCR in patients with persistent cough.

Role of IgG-seropositivity to Chlamydia pneumoniae in early thrombotic events after coronary stent placement

AIMS

Since infection of endothelial or smooth muscle cells with Chlamydia pneumoniae increased expression of tissue factor and plasminogen activator inhibitor I (PAI-1), C. pneumoniae might be involved in triggering acute thrombotic events in patients with coronary artery disease. Therefore, we explored a potential relationship between IgG-seropositivity to C. pneumoniae and early thrombotic events after coronary stent placement.

METHODS AND RESULTS

In a prospective randomized placebo-controlled study 1010 patients with successful coronary stent placement received roxithromycin or placebo for 4 weeks after coronary stent placement, which showed no effect of roxithromycin on early thrombotic events, as expected. Venous blood samples were collected from patients immediately before treatment. Plasma was analyzed for C. pneumoniae-specific IgG antibody levels by microimmuno-fluorescence. Thrombotic events were defined as death, non-fatal myocardial infarction, or urgent target vessel reintervention within 30 days after stent placement. We found no significant difference concerning the frequency of early thrombotic events in patients positive or negative for C. pneumoniae-specific antibodies. If patients were stratified according to their antibody levels, again no significant difference in the frequency of thrombotic events was observed.

CONCLUSION

Our findings do not suggest a role of C. pneumoniae in the development of early complications after stent placement.

Evaluation of an anti-chlamydial antibiotic therapy influence on asthma patients

Chlamydia pneumoniae is one of the most frequent pathogens causing airways infections. Contribution of chronic chlamydial infection to the following diseases: asthma, POChP, coronary heart disease, abdominal aortic aneurysm, is particularly interesting. The connection between such infection and bronchial asthma was described in the literature in 1991. C. pneumoniae often causes asthma exacerbation; it is suggested that it also may be an etiologic factor of the disease. In a group of 55 subjects with chronic, stable bronchial asthma treated in the Pulmonary Department, serologic characteristic of C. pneumoniae infection was found in 34 patients (61,8%). Thirteen of these subjects agreed to participate in the study. They were divided into two groups; placebo was administered to the first one and azithromycin in a dose of 1000 mg once a week--to the other one. The research was conducted using the double blind trial method. Anti-chlamydial antibody level was evaluated before and after treatment. Spirometry tests as well as subjective estimation of physical fitness and dyspnoea degree were also determined. In comparison with 'the placebo group', statistically significant improvement in respiratory parameters 'in the treated group' was not ascertained.

Reduced progression of early carotid atherosclerosis after antibiotic treatment and Chlamydia pneumoniae seropositivity

BACKGROUND

Chlamydia pneumoniae (Cp) infection has been associated with atherosclerosis, and a beneficial effect of antibiotic therapy on future cardiovascular events was described.

METHODS AND RESULTS

We evaluated the effect of roxithromycin therapy (150 mg twice daily for 30 days) on the progression of the intima-to-media thickness (IMT) of the common carotid artery using duplex ultrasonography in a prospective and randomized trial with a follow-up of 2 years in 272 consecutive patients with ischemic stroke aged over 55 years in whom the first IMT measurement and Cp testing (IgG and IgA) were performed at least 3 years before the roxithromycin treatment. Cp IgG antibodies (> or =1:64) were initially found in 123 (45%) patients and IgA antibodies (> or =1:16) in 112 (41%) patients. During the 3 years before antibiotic therapy, Cp-positive patients showed an enhanced IMT progression, even after adjustment for other cardiovascular risk factors (0.12 [95% CI, 0.11 to 0.14] versus 0.07 [0.05 to 0.09] mm/year; P<0.005). The 62 Cp-positive patients given roxithromycin showed a significantly decreased IMT progression after 2 years compared with the Cp-positive patients without therapy (0.07 [0.045 to 0.095] versus 0.11 [0.088 to 0.132] mm/year; P<0.01). No significant difference in the occurrence of future cardiovascular events was found between both groups during follow-up. No change of IMT was observed in Cp-negative patients given roxithromycin (n=74) compared with those without therapy (0.06 [0.03 to 0.09] versus 0.07 [0.05 to 0.09] mm/year).

CONCLUSIONS

Our findings suggest a positive impact of antibiotic therapy on early atherosclerosis progression in Cp-seropositive patients with cerebrovascular disease.

The intracellular life of chlamydiae

The ability to cause persistent infection is one of the major characteristics of all chlamydial species in their appropriate hosts. Persistent infection with Chlamydia trachomatis and Chlamydia pneumoniae has been implicated in the pathogenesis of many chronic diseases, some initially not thought to be infectious, including pelvic inflammatory disease, arthritis, asthma, and atherosclerosis. Chlamydiae have a unique developmental cycle with morphologically distinct infectious and reproductive forms: elementary (EB) and reticulate bodies (RB). Chlamydiae appear to circumvent the host endocytic pathway and inhabit a nonacidic vacuole that is dissociated from late endosomes and lysosomes. Chlamydiae also have been demonstrated to enter a persistent state after treatment with cytokines such as interferon-gamma (IFN-gamma), treatment with antibiotics, or restriction of certain nutrients, or to enter this state spontaneously under certain culture conditions. While the organism is in the persistent state, metabolic activity is reduced, and the organism is often refractory to antibiotic treatment. Ultrastructural analysis of IFN-gamma-treated C pneumoniae demonstrates atypical inclusions containing large reticulate-like aberrant bodies with no evidence of redifferentiation into EBs. Persistent C pneumoniae infection appears to be associated with continued expression of genes associated with DNA replication but not with those genes involved with bacterial cell division. The latter observation may explain the appearance of the large abnormal RBs seen in ultrastructural studies. Studies of the association of chlamydiae with chronic disease have been hampered by difficulties in diagnosing chronic, persistent infection with the organism, which, in turn, render determining the efficacy of antibiotic therapy very difficult.

Chlamydia pneumoniae and atherosclerosis

Chlamydia pneumoniae, a human respiratory pathogen, has been linked to atherosclerotic disease based on sero-epidemiologic studies, direct detection of the organism in atherosclerotic lesions, animal experiments and tissue culture. In this review paper we propose to interpret results in line with the biology of Chlamydia with persistence of Chlamydia pneumoniae antigens in the pathogenesis of atherosclerosis rather than viable bacteriae.

KN-62 enhances Chlamydia pneumoniae-induced p44/p42 mitogen-activated protein kinase activation in murine fibroblasts and attenuates in vitro infection

Chlamydia pneumoniae elementary bodies were demonstrated to increase the proliferation of murine fibroblast cell line L-929 and rapidly activate p44/p42 mitogen-activated protein kinase (MAPK) in a protein kinase C (PKC) and protein kinase A (PKA)-independent way. Ca(2+)/calmodulin-dependent protein kinase (CaM kinase) inhibitor KN-62 significantly enhanced C. pneumoniae-induced MAPK phosphorylation, suggesting negative control of CaM kinase pathway on the MAPK cascade. In in vitro infection assay, the upstream MAPK kinase 1/2 inhibitor U0126 increased 2.5-fold C. pneumoniae infectivity in L-929 cells, while KN-62 reduced the infection by 36%. Our findings provide insight into the molecular mechanisms of bacterium-host cell interactions and demonstrate the protective role of MAPK in murine fibroblasts, suggesting novel therapeutic approaches to the treatment and prevention of chlamydial infections.

[Chronic pharyngitis and macrolides]

We have noticed that macrolides can improve the main symptoms of many patients with chronic pharyngitis. We feel that the efficacy of macrolides for chronic pharyngitis can be due to the anti-inflammatory effect of this group of antibiotics. However, we think that at present the use of macrolides is not the therapy of choice for chronic pharyngitis.

Mycoplasma pneumoniae and Chlamydia pneumoniae cause lower respiratory tract disease in paediatric patients

New studies suggest that Mycoplasma pneumoniae and Chlamydia pneumoniae play a more significant role as causes of lower respiratory tract infections in childhood than was previously thought. In particular, the incidence of infections caused by these pathogens is high in children aged less than 5 years, the infections themselves seem to be a possible cause of wheezing, and may present a more complicated course when not treated with adequate antimicrobial agents. However, despite the increasing pathogenic significance of M. pneumoniae and C. pneumoniae, progress in fighting them is hampered by the lack of rapid and standardized diagnostic methods. This not only makes it practically impossible for practitioners to make a specific microbiological diagnosis, but has also had an adverse effect on treatment trials and has generated some questionable results. Carefully randomized and controlled trials are clearly needed to examine the effectiveness of different antibiotics against M. pneumoniae or C. pneumoniae and the optimal duration of therapy in various patient populations.

An open, comparative pilot study of thiamphenicol glycinate hydrochloride vs clarithromycin in the treatment of acute lower respiratory tract infections due to Chlamydia pneumoniae

The aim of this study was to evaluate the efficacy and tolerability of thiamphenicol glycinate hydrochloride (TGH) i.m. versus clarithromycin in acute lower respiratory infections due to Chlamydia pneumonia. 113 patients with suspected pneumonia were screened. 40 patients with IgM and/or IgA titers > or = 1:16 and/or IgG titers > or = 1:512 were assigned to 10 days of treatment with TGH 1500 mg daily or clarithromycin 1000 mg daily. 34 patients were considered a clinical success. 33 patients were a radiological success. 22 patients showed a decrease in IgG values. 3 patients had an increase in IgG values. Blood/urine values presented no clinically significant variations. Clinical efficacy was similar in both treatment groups. These are the first results confirming in vivo the recent in vitro evidence that TGH is effective against acute lower respiratory tract infections due to C. pneumoniae, thus representing an alternative therapy to clarithromycin.

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.

Effect of azithromycin treatment on endothelial function in patients with coronary artery disease and evidence of Chlamydia pneumoniae infection

BACKGROUND

It has been suggested that infection with Chlamydia pneumoniae(CPn) can trigger inflammatory mechanisms that may in turn impair vascular endothelial function. The aim of the present study was to assess whether treatment with the macrolide antibiotic azithromycin improves endothelial function in patients with coronary artery disease and antibodies positive to CPn.

METHODS AND RESULTS

We carried out a randomized, prospective, double-blind, placebo-controlled trial in 40 male patients (mean age, 55+/-9 years) with documented coronary artery disease and positive CPn-IgG antibody titers. After baseline evaluation, patients were randomized to receive either azithromycin or placebo for 5 weeks. Flow-mediated dilation (FMD) of the brachial artery and E-selectin, von Willebrand factor, and C-reactive protein (CRP) levels were assessed at study entry and at the end of the treatment period. Our results showed that patients who received azithromycin had a significant improvement in FMD (mean change, 2.1+/-1.1%; P<0.005). In contrast, FMD was not significantly changed in the placebo group (mean change, -0.02+/-0.2%, P=0.64). Azithromycin therapy also resulted in a significant decrease of E-selectin and von Willebrand factor levels. CRP levels were not significantly altered by treatment with either azithromycin or placebo. Beneficial effects of azithromycin treatment were independent from the presence of low (<1:32) or high (> or =1:32) CPn antibody titers.

CONCLUSIONS

Our findings indicate that treatment with azithromycin has a favorable effect on endothelial function in patients with documented coronary artery disease and evidence of CPn infection irrespective of antibody titer levels. Whether these favorable actions of antibiotic treatment will translate into a beneficial effect on atherogenesis and cardiac events needs further investigation.

In vitro susceptibility and eradication of Chlamydia pneumoniae cardiovascular strains from coronary artery endothelium and smooth muscle cells

Recovery of viable Chlamydia pneumoniae from atheromas of coronary heart diseases patients has initiated pilot studies to eradicate C. pneumoniae from vascular tissue by antibiotic treatment. To provide data for the selection of effective antibiotics, we investigated the in vitro activity of anti-chlamydial antibiotics to eliminate vascular strains of C. pneumoniae from coronary endothelial and smooth muscle cells, celltypes that are involved in the pathogenesis of atherosclerosis.

METHODS

The susceptibility of the obligate intracellular chlamydiae was studied in primary coronary endothelial cells, smooth muscle cells and immortalized epithelial cells. Minimal inhibitory concentrations (MICs) were determined for ofloxacin, levofloxacin, trovafloxacin, moxifloxacin, erythromycin, azithromycin, roxithromycin, rifapentin and rifampin.

RESULTS

In vitro, rifampin was the most effective drug overall. Moxifloxacin and trovafloxacin were as effective as the macrolides of which roxithromycin was the most active one.

CONCLUSIONS

Actively replicating C. pneumoniae can be eliminated in vitro from cell types, involved in the pathogenesis of atherosclerosis by various antibiotics. These data provide an experimental background for the selection of antibiotics in clinical eradication studies and will help to assess the potential success of prevention and eradication therapies.

Mycoplasma and Chlamydia pneumonia in pediatrics

Mycoplasma pneumoniae and Chlamydia pneumoniae are common respiratory pathogens in children 5 years of age and older. Although distinctly different in structure, these organisms share similar epidemiologic and clinical characteristics in human infection and disease. Pneumonia caused by these organisms usually occurs after infection of the upper respiratory tract, but may occur in the absence of antecedent upper respiratory infection. Diagnosis of infection with C. pneumoniae and M. pneumoniae is most often based on clinical findings alone, though definitive diagnosis of infection with either organism may be confirmed through serologic methods, culture, and nucleic acid-detection methods such as polymerase chain reaction. Macrolide antibiotics are highly effective in the treatment of infected children, leading to rapid clinical resolution and excellent long-term out-come in the majority of patients.

Iron chelation and hydroxyl radical scavenging reduce the inflammatory response of endothelial cells after infection with Chlamydia pneumoniae or influenza A

BACKGROUND

Chronic low-grade inflammation is associated with increased risk of vascular diseases. The source of inflammation is unknown but may well be chronic and/or repetitive infections with microorganisms. Direct infection of endothelial cells (ECs) may also be a starting point for atherogenesis by initiating endothelial procoagulant activity, increased monocyte adherence and increased cytokine production. We hypothesized that iron-mediated intracellular hydroxyl radical formation after infection is a key event in triggering the production of interleukin-6 (IL-6) by ECs in vitro.

METHODS

Cultured ECs were incubated with Fe(II) and Fe(III) or infected with Chlamydia pneumoniae or influenza A/H1N1/Taiwan/1/81 for 48 and 24 h, respectively. To determine the role of iron and reactive oxygen species, cells were coincubated with the H2O2 scavenger N-acetyl-l-cysteine, with the iron chelator deferoxamine (DFO) or with the intracellular hydroxyl radical scavenger dimethylthiourea (DMTU). After the incubation periods, supernatants were harvested for IL-6 determination.

RESULTS

Incubating ECs with Fe(II) and Fe(III) resulted in increased IL-6 production. Similarly, infection with C. pneumoniae and influenza A also induced an IL-6 response. Coincubating ECs with DFO or DMTU blocked this response. Nuclear factor-kappaB activity was increased after infection and blocked by coincubation with DFO or DMTU.

CONCLUSION

Cultured ECs respond to infection and iron incubation with increased production of IL-6. Iron, the generation of intracellular hydroxyl radical and NF-kappaB activity are essential in cellular activation, suggesting that reactive oxygen species generated in the Haber-Weiss reaction are essential in invoking an immunological response to infection by ECs.

[Acute polyradiculoneuropathy after Chlamydia pneumoniae infection]

A 36-year-old woman presented acute polyradiculoneuropathy following Chlamydia pneumoniae infection. Although electrophysiologic studies were normal, clinical features were typical of Guillain-Barré syndrome (GBS). Anti-ganglioside GM1 antibodies were positive. Two other cases of GBS following Chlamydia pneumoniae infection have been reported, but no specific feature emerges. Outcome was good in our patient after intravenous globulin then antibiotic therapy. Our case supports the notion that Chlamydia pneumoniae infection can induce GBS. The association is probably underestimated.

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.

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.

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.

Community-acquired pneumonia: role of atypical organisms

M. pneumoniae infection occurs world-wide and is the most common cause of community-acquired pneumonia (CAP) in the 5 to 20 year-old age group. The most reliable diagnostic test is enzyme immunoassay that allows immunoglobulin (Ig)G and IgM titration and presents 92% sensitivity and 95% specificity on paired samples. Potentially active drugs are tetracyclines, macrolides, ketolides, lincosamides, streptogamines, chloramphenicol, and fluoroquinolones. The incidence of Legionella infection, in spite of its world-wide diffusion, is highly variable in different studies, ranging from 1% to 27% of CAP. The most likely mode of transmission is direct inhalation from Legionella-contaminated water-supply systems. Extrapulmonary manifestations are relatively common but nonspecific. However, some signs and symptoms may raise the suspicion of Legionella infection: a sputum Gram stain with a high number of neutrophils without any organism, hyponatremia, and diarrhea in a critically ill patient. Urinary radioimmunoassay (RIA) antigen detection is the method of choice for L. pneumophila serogroup 1. The best treatment regimen is a full three-week treatment with a macrolide (erythromycin, clarithromycin, azithromycin). An alternative treatment regimen may be the association of second generation fluoroquinolones with tetracyclines. A notable improvement in most of the new fluoroquinolones is their activity against Legionella, so that their use as single agent may be hypothesised even if clinical data are still insufficient for a definitive indication. Chlamydia pneumoniae account for 6-20% of CAP depending on several factors such as setting of the studied population, age group examined, and diagnostic methods used. The current gold standard for serological diagnosis of acute infection is microimmunofluorescence testing. Tetracyclines and erythromycin show good in vitro activity and so far have been the most commonly employed drugs in the treatment of C. pneumoniae infection. New macrolides, ketolides, and new fluoroquinolones are other potentially effective drugs.

Roxithromycin in prevention of acute coronary syndrome associated with Chlamydia pneumoniae infection: a randomized placebo controlled trial

The role of Chlamydia pneumoniae infection in precipitating acute coronary syndrome (ACS) is unclear. Some studies have indicated that intervention with macrolide antibiotics might reduce coronary events in patients with ACS. A double blind, randomized, placebo-control trial was conducted on 84 ACS patients. Patients were randomized to 30 days of treatment with roxithromycin (150 mg, twice daily) or matching placebo. The follow-up period was 90 days, and the primary clinical end point included cardiovascular death, unplanned revascularization and recurrent angina/MI. Anti-C. pneumoniae IgG positive in 24 of 43 (55.8%) patients in the roxithromycin group and 23 of 41 (56.1%) patients in the placebo group. Anti-C. pneumoniae IgA positive in 20 of 43 (46.5%) patients in the roxithromycin group and 13 of 41 (31.7%) patients in the placebo group. Thirty-three cardiac events occurred (2 cardiovascular deaths, 9 CABG, 12 PTCA and 10 recurrent angina/MI) with 17 events in the roxithromycin group and 16 events in the placebo group. There was no significant difference of cardiac events between the roxithromycin and placebo groups. The present study suggests that antibiotic therapy with roxithromycin is not associated with reduction of cardiac events as reported by other investigators. However, therapeutic interventions may need to be specifically targeted to a group of patients who are confirmed with chronic C. pneumoniae infection.

Emerging role of Mycoplasma pneumoniae and Chlamydia pneumoniae in paediatric respiratory-tract infections

Increased use of specialised diagnostic techniques over the past 10 years has allowed considerable new information to be obtained concerning Mycoplasma pneumoniae and Chlamydia pneumoniae infections. In children, these pathogens seem to have a more important role in causing respiratory-tract infections than previously thought; they have been associated with wheezing, and they are also frequent in children aged under 5 years. Contrary to original belief, no clinical, laboratory, or radiological findings seem to be unique to M. pneumoniae or C. pneumoniae; furthermore, there is no rapid and cost-effective diagnostic test capable of identifying these pathogens. Appropriate antimicrobial treatment of the infections they cause is needed to reduce the recurrent episodes of wheezing and other respiratory symptoms, to decrease morbidity, and to avoid the spread of the pathogens. However, a number of therapeutic issues remain unsolved.

The role of atypical pathogens in community-acquired pneumonia

The atypical pathogens in community-acquired pneumonia traditionally have included Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella spp. Recent studies documenting their epidemiology and clinical characteristics have shown that these organisms are indistinguishable from the pneumococcus. Furthermore, therapy no longer depends on the specific bacterial cause of community-acquired pneumonia. Etiologic diagnosis is still difficult, although new methods are becoming available. This article focuses on these issues and on why the term atypical is no longer meaningful.

Trial of roxithromycin in subjects with asthma and serological evidence of infection with Chlamydia pneumoniae

An association has been reported between chronic infection with Chlamydia pneumoniae and the severity of asthma, and uncontrolled observations have suggested that treatment with antibiotics active against C. pneumoniae leads to an improvement in asthma control. We studied the effect of roxithromycin in subjects with asthma and immunoglobulin G (IgG) antibodies to C. pneumoniae > or = 1:64 and/or IgA antibodies > or = 1:16. A total of 232 subjects, from Australia, New Zealand, Italy, or Argentina, were randomized to 6 wk of treatment with roxithromycin 150 mg twice a day or placebo. At the end of 6 wk, the increase from baseline in evening peak expiratory flow (PEF) was 15 L/min with roxithromycin and 3 L/min with placebo (p = 0.02). With morning PEF, the increase was 14 L/min with roxithromycin and 8 L/min with placebo (NS). In the Australasian population, the increase in morning PEF was 18 L/min and 4 L/min, respectively (p = 0.04). At 3 mo and 6 mo after the end of treatment, differences between the two groups were smaller and not significant. Six weeks of treatment with roxithromycin led to improvements in asthma control but the benefit was not sustained. Further studies are necessary to determine whether the lack of sustained benefit is due to failure to eradicate C. pneumoniae.

Treatment of Chlamydia pneumoniae infection with roxithromycin and effect on neointima proliferation after coronary stent placement (ISAR-3): a randomised, double-blind, placebo-controlled trial

BACKGROUND

Vascular infection with Chlamydia pneumoniae might boost inflammatory responses that play a pivotal part in neointima formation, which is the main cause of restenosis after stenting. Our aim was to investigate whether or not treatment of C pneumoniae infection with antibiotics prevents restenosis after coronary stent placement.

METHODS

We enrolled 1010 consecutive patients with successful coronary stenting into a randomised, double-blind trial. Patients received the macrolide antibiotic roxithromycin 300 mg once daily for 28 days (506), or placebo (504). Primary endpoint was frequency of restenosis (diameter stenosis >50%) at follow-up angiography, and secondary endpoint was rate of target vessel revascularisation during the year after stenting. A prespecified secondary analysis addressed treatment effect with respect to titre of C pneumoniae in serum. Analysis was by intention to treat.

FINDINGS

Rate of angiographic restenosis was 31% (157 lesions) in the roxithromycin group and 29% (148) in the placebo group (relative risk 1.08 [95% CI 0.92-1.26]; p50.43), corresponding to a rate of target vessel revascularisation of 19% (120) and 17% (105), respectively (1.13 [0.95-1.36]; p50.30). The combined 1-year rates of death and myocardial infarction were 7% (36) in the roxithromycin group and 6% (30) in the placebo group (p50.45). We showed a significant interaction between treatment and C pneumoniae antibody titre (p50.038 for restenosis, p50.006 for revascularisation), favouring roxithromycin at high titres (adjusted odds ratios at a titre of 1/512 were 0.44 [0.19-1.06] and 0.32 [0.13-0.81], respectively).

INTERPRETATION

Non-selective use of roxithromycin is inadequate for prevention of restenosis after coronary stenting. There is, however, a differential effect dependent on C pneumoniae titres. In patients with high titres, roxithromycin reduced the rate of restenosis.