The epidemic cycle of Chlamydia pneumoniae infection in eastern Finland, 1972-1987

Multi-peptide ELISAs overcome cross-reactivity and inadequate sensitivity of conventional Chlamydia pneumoniae serology

Cross-reactivity of classical chlamydial antigens compromises Chlamydia (C.) pneumoniae serology. By testing with 185 human antisera, we expanded 18 previously discovered C. pneumoniae-specific B-cell epitopes to 48 peptide antigens from 12 C. pneumoniae immunodominant proteins. For specific detection of antibodies against C. pneumoniae, we developed novel ELISAs with strongly reactive individual peptide antigens and mixtures of these peptides. By comparison to a composite reference standard (CRS) for anti-C. pneumoniae antibody status of human sera, the top-performing CpnMixF12 peptide assay showed 91% sensitivity at 95% specificity, significantly higher than 4 commercial anti-C. pneumoniae IgG ELISAs (36-12% sensitivity at 95% specificity). Human C. pneumoniae (Cpn) and C. trachomatis (Ctr) seroreactivity was 54% biased towards co-positivity in commercial Cpn and Ctr ELISAs, but unbiased in Cpn and Ctr peptide antibody assays, suggesting severe cross-reactivity of commercial ELISAs. Using hyperimmune mouse sera against each of 11 Chlamydia spp., we confirm that commercial Cpn and Ctr ELISA antigens are cross-reactive among all Chlamydia spp., but Cpn and Ctr peptide antigens react only with antisera against the cognate chlamydial species. With simultaneously high specificity and sensitivity, and convenient use for non-specialized laboratories, these ELISAs have the potential to improve serodiagnosis of C. pneumoniae infection.

Chlamydia pneumoniaeRespiratory Infections in Taiwan

To understand the epidemiology of Chlamydia pneumoniae acute infections in Taiwan, we collected 116 paired and 244 single sera from patients suspected of C. pneumoniae infection and conducted microimmunofluorescence test. Eighty-three patients (83/360, 23%) met the diagnostic criteria of current C. pneumoniae infection. The C. pneumoniae infections were significantly higher in men than in women (P< or =0.0001) and were most frequent in the group of 40-49 year-olds, and the people older than 70 years old. C. pneumoniae infection often occurred in the late autumn lasting to the cold winter and in the transition period between the spring and summer.

Zoonotic Chlamydophila psittaci infections from a clinical perspective

Human psittacosis is a zoonotic infectious disease which is caused by the obligate intracellular bacterium Chlamydophila psittaci. Transmission of the disease usually originates from close contact with infected birds, most frequently in the context of the poultry industry, and from contact with Psittaciformes (cockatoos, parrots, parakeets and lories). Due to a low awareness of the disease and a variable clinical presentation psittacosis is often not recognised as such by general practitioners. This review therefore gives an overview of the epidemiology, symptoms, diagnosis and possible treatments for psittacosis in humans. The current case definition for epidemiological surveillance, as issued by the CDC, is discussed, as well as the possible emergence of Cp. psittaci antibiotic-resistant strains. There is an urgent need for information and for awareness campaigns directed at professional health care workers and the general public. In addition, a broader use of new diagnostic methods in medical laboratories and the development of prophylactics are called for.

Prevalence and persistence of Chlamydia pneumoniae antibodies in healthy laboratory personnel in Finland

The rates of Chlamydia pneumoniae seroconversions suggesting acute primary infections or reinfections and the prevalences of antibodies were followed up among healthy laboratory workers. Annual serum samples were collected from 47 persons in Helsinki from 1958 to 1990 and from 40 persons in Oulu from 1994 to 1999. C. pneumoniae species-specific immunoglobulin G (IgG), IgA, and IgM antibodies were measured by microimmunofluorescence (MIF) in 407 sera from Helsinki. The 185 sera collected in Oulu were tested both by MIF and by commercial enzyme immunoassay (EIA). During the follow-up periods of 31 years in Helsinki and 6 years in Oulu, seroconversions were demonstrated by MIF in 45% and 15% of the study groups, respectively. In Helsinki 9% of the persons seroconverted twice during the follow-up period. By MIF, the total incidence rate per 100 person-years at risk was 6.9 in Helsinki and 4.9 in Oulu, and annual incidence rates varied from 0 to 15.4. By EIA, annual incidence rates in Oulu varied from 0 to 10.8. The seroconversions by MIF were usually not confirmed by EIA and vice versa. Prevalence and persistence rates, respectively, of IgA antibodies were higher in EIA (62% and 26%) than in MIF (26% and 17%), whereas the figures for IgG were quite similar. The prevalence of IgG and IgA antibodies was higher in older persons than in younger ones. The presence of antibodies did not offer protection from reinfection.

Serum Lipid Profiles Poorly Correlate With Chlamydia pneumoniae , Helicobacter pylori , and Cytomegalovirus Seropositivity in Prospectively Followed-Up Healthy Children

Objective— Chronic Chlamydia pneumoniae ( Cpn ), Helicobacter pylori ( Hp ), and herpes virus infections have been associated with atherogenic serum lipid profile and an excess of cardiovascular events in adults. Because mechanisms leading to atherosclerosis are active since early childhood, we examined whether Cpn, Hp , or cytomegalovirus (CMV) seropositivity relates to serum lipid, lipoprotein, or apolipoprotein concentrations in children. We also looked for factors increasing probability of Cpn seropositivity in children.

Methods and Results— Cpn- specific IgG and IgA, as well as Hp- specific and CMV-specific IgG antibodies were assessed by enzyme immunoassay in 199 apparently healthy children, followed-up from 7 to 11 years of age. Serum lipid profiles were studied at the ages of 7, 9, and 11 years using standard methods. Neither seroconversion to Cpn IgG or IgA antibody positivity nor persistent seropositivity for Cpn, Hp , or CMV was associated with proatherogenic serum lipid values. Children with siblings were more likely to possess Cpn antibodies than children without siblings (IgG: OR, 5.24; 95% CI, 1.63 to 16.82; IgA: OR, 3.32; 95% CI, 1.15 to 9.57).

Conclusions— These data suggest that contrary to the observations in adults, Cpn, Hp , and CMV seropositivity in otherwise healthy children is not associated with disturbances in serum lipid profile.

Why Chlamydia pneumoniae is associated with asthma and other chronic conditions? Suggestions from a survey in unselected 9 yr old schoolchildren

Despite numerous studies demonstrating an association between asthma and many other chronic conditions and signs of Chlamydia pneumoniae (Cp) infection, the role of Cp in the pathogenesis of these illness remain still unclear. We investigated the prevalence of Cp antigen in the upper airways and the prevalence of detectable Cp serum antibodies in an unselected population of 207 9-yr-old schoolchildren. We also sought the presence of asthma, chronic or recurrent respiratory symptoms by means of questionnaire completed by the parents. Nasal aspirate, blood sampling and allergen skin prick tests were also performed. None of the children had obvious signs of acute infection at physical examination. Cp DNA was detected in nasal aspirates from 20 of the 207 children tested and serum IgG antibodies for Cp in 68 children. No association was found between atopy or history of atopic illness and the presence of Cp DNA or antibody production. This finding is explained by the fact that our study was conducted in an unselected childhood population, inherently including few children with asthma. A strong association between the status of antigen carrier and the presence of detectable Cp serum immunoglobulin (Ig)G or IgM suggests that subjects with detectable Cp antibodies have an impaired ability to eliminate this pathogen when infected. Because Cp eradication requires a strong Th1 lymphocyte response, the previously proven association between Cp and asthma, might reflect the known association of asthma with Th2-oriented lymphocytic activity.

Seroprevalence of Chlamydia pneumoniae infection in Taiwan

OBJECTIVES

To survey the seroprevalence of Chlamydia pneumoniae (C. pneumoniae) infection in healthy subjects in Taiwan.

MATERIALS AND METHODS

We used microimmunofluorescence antibody assay to survey the prevalence of antibodies to C. pneumoniae in 620 serum samples from healthy subjects aged 6 months to 86 years in Taiwan.

RESULTS

The mean prevalence (+/-SD) of IgG antibodies against C. pneumoniae at titer greater than or equal 1:16 was 55.8% (range 7.8-81.8%). The antibody prevalence was low in children under the age of 10 years (7.8%), and increased rapidly with age. Most individual acquired infection during the second and third decades of life with highest antibody prevalence reached up to 81.8% at fifth decade of life and remained high (70%) thereafter.

CONCLUSIONS

Chlamydia pneumoniae infection is highly endemic in Taiwan. These data contribute to the understanding of asymptomatic infections with C. pneumoniae in general population and should serve as a basis for studies on the role of C. pneumoniae infections and their related diseases.

A prospective study of Chlamydia pneumoniae antibodies in children between 7 months and 8 years of age

To provide insight into the appearance and longitudinal course of Chlamydia pneumoniae antibodies in childhood, C. pneumoniae immunoglobulin G (IgG), IgA and, in selected children, IgM antibodies were measured annually in 199 healthy children, followed prospectively from age 7 months to age 8 y (number of samples 1225) using a commercial enzyme immunoassay kit. IgG antibodies to C. pneumoniae were common throughout the follow-up, and the values declined rapidly after apparent infections during early childhood. Of the 128 identified seroconversions, 94 were probably primary infections and 34 reinfections. IgM antibodies were detected in 28% of the samples that showed a clear increase in IgG. IgA antibodies were scarce before 2 y of age, but their proportion then increased gradually. At the ages of 7 and 8 y, 10% of the children had clearly positive IgG and IgA antibody values. Increases in IgG were not associated with clinical respiratory symptoms. This study shows that C. pneumoniae infections probably occur commonly already at an early age, and that the infections are often asymptomatic. Consecutive high IgG and IgA antibody concentrations at the ages of 7 and 8 y indicate that persistent seropositivity for both antibodies may already develop in young children.

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 infections in patients with community-acquired pneumonia in Slovenia

It is well known that Chlamydia pneumoniae is an important respiratory pathogen. In this study, the prevalence of specific antibodies to C. pneumoniae in hospitalized patients with community-acquired pneumonia (943 adult females, 990 adult males and 185 children) was evaluated over a period of 7 y (1993-99). Two serum samples were obtained from all of the patients: 1 on admission and the other 3 weeks later. The specimens were tested for C. pneumoniae IgG, IgM and IgA antibodies by means of a microimmunofluorescence test. Acute infection with C. pneumoniae was determined in 9.4% of females and 13.1% of males. In children and adolescent patients, the microimmunofluorescence test showed recent infection in 8.6% of cases, with the highest prevalence occurring in the 11-15 y age group. The highest prevalence of C. pneumoniae pneumonia was found in 1995 and 1999: 15.4% and 13.6% respectively. The results obtained showed that C. pneumoniae is persistently present in the population of Slovenia.

Seroepidemiology of Chlamydia pneumoniae in Japan between 1991 and 2000

AIM

To clarify the endemic and epidemic status of Chlamydia pneumoniae in Japan, the incidence of anti-C pneumoniae antibody was evaluated over a period of 10 years.

METHOD

Serum samples were collected from 4756 healthy individuals aged 6 months to 88 years (2488 male and 2268 female individuals) between 1991 and 2000. The antibody titre was determined by a microimmunofluorescence test.

RESULTS

After stratification by age and sex in each year, distinct peaks with prevalences of 73.3% and 73.0% were noted in 1993 and 1999, respectively. The lowest prevalence rate was seen in 1996 (59.0%). The epidemic cycle has been estimated to be almost six years in this geographical area.

CONCLUSIONS

Chlamydia pneumoniae infection is highly endemic in Japan, as it is in Western countries, and there is a year to year variability. Long term studies in Japan are needed to clarify the epidemic occurrence of C pneumoniae infection.

Prevalence of Chlamydia pneumoniae in peripheral blood mononuclear cells in Italian patients with acute ischaemic heart disease

Chlamydia pneumoniae infection generally starts in the respiratory tract and probably disseminates systemically in the blood stream within alveolar macrophages. We investigated the prevalence of C. pneumoniae DNA in peripheral blood mononuclear cells (PBMC) in patients with acute ischaemic heart disease. Samples of blood were obtained from 93 consecutive patients with acute ischaemic heart disease and from 42 healthy subjects, for detection of C. pneumoniae DNA in PBMC by polymerase chain reaction (PCR) and for serology. C. pneumoniae DNA in PBMC was detected in 25.8% (24/93) of the patients with acute ischaemic heart disease and in 4.8% (2/42) of the healthy subjects (P=0.008). C. pneumoniae IgG was found in 76.3% of patients and in 45.2% of healthy subjects (P=0.0008) while C. pneumoniae IgA was found in 59.1% and in 33.3%, respectively (P=0.01). No correlation was found between anti-C. pneumoniae antibody titers and positive PCR results. The detection of C. pneumoniae DNA in PBMC may aid in selecting patients who may benefit from antibiotic treatment; however, to support this contention, longitudinal studies on patients treated with antibiotics would also be necessary.

Microbial etiology of community-acquired pneumonia in the adult population of 4 municipalities in eastern Finland

To determine the etiology of community-acquired pneumonia in the adult population of a defined area, specific antibody responses in paired serum samples, levels of circulating pneumococcal immune complexes in serum samples, and pneumococcal antigen in urine were measured. Samples (304 paired serum samples and 300 acute urine samples) were obtained from 345 patients > or =15 years old with community-acquired, radiologically confirmed pneumonia, which comprised all cases in the population of 4 municipalities in eastern Finland during 1 year. Specific infecting organisms were identified in 183 patients (including 49 with mixed infection), as follows: Streptococcus pneumoniae, 125 patients; Haemophilus influenzae, 12; Moraxella catarrhalis, 8; chlamydiae, 37 (of which, Chlamydia pneumoniae, 30); Mycoplasma pneumoniae, 30; and virus species, 27. The proportion of patients with pneumococcal infections increased and of those with Mycoplasma infections decreased with age, but for each age group, the etiologic profile was similar among inpatients and among outpatients. S. pneumoniae was the most important etiologic agent. The annual incidence of pneumococcal pneumonia per 1000 inhabitants aged > or =60 years was 8.0.

Epidemiologic association of Chlamydia pneumoniae and atherosclerosis: the initial serologic observation and more

About 70% of persons with acute myocardial infarction (AMI) show a seroresponse to a chlamydial lipopolysaccharide (LPS) epitope. Elevated titers against Chlamydia pneumoniae in sera from such patients point to an exacerbation in a chronic infection as does a change in the nature of immune complexes containing chlamydial LPS. The presence of antibodies to C. pneumoniae proteins in immune complexes suggests an intimate association of the pathogen with the vascular system. In the first prospective study, elevated antibody titers or immune complexes containing chlamydial LPS were an independent significant risk factor (odds ratio, </=2.6) for AMI 3-6 months before the cardiac incident. The majority of later seroepidemiologic studies have verified the association. However, since serologic markers for C. pneumoniae infection also seem to be associated with uncomplicated atherosclerosis and other chronic conditions, their predictive value for cardiac events is small.

Antibiotics in the prevention and treatment of coronary heart disease

Seroepidemiology, pathology, and animal studies provide evidence for a possible association between Chlamydia pneumoniae infections and atherosclerosis, coronary heart disease, and myocardial infarction. If this association exists, then exposure to certain antibiotics may positively affect the clinical course after an acute ischemic cardiac event (secondary prevention) and affect the risk of developing a first-time myocardial infarction (primary prevention). Preliminary evidence from clinical trials suggests that treatment with new macrolide antibiotics may improve outcome after ischemic events, and evidence from a large case-control analysis indicates that exposure to tetracyclines or quinolones may reduce the risk of developing a first-time myocardial infarction. However, antibiotics for the treatment or prevention of ischemic heart disease must not be recommended yet. This review of published studies briefly summarizes the currently available literature on the effects of antibiotics on the risk of developing coronary heart disease and myocardial infarction.

Chlamydia pneumoniae in atherosclerosis

Chlamydia pneumoniae is currently the infectious agent most often associated with the inflammation found in atherosclerosis. The seroepidemiological association and the actual presence of pathogen in lesions has been confirmed in numerous studies, in which technical difficulties seem to be the only limitation. Besides animal experiments and intervention trials, we need information of possible pathogenic mechanisms. Recently, several studies have suggested mechanisms by which C. pneumoniae infection could participate in the development of atherosclerosis.

Pneumonia adquirida na comunidade em pacientes tratados ambulatorialmente: aspectos epidemiológicos, clínicos e radiológicos das pneumonias atípicas e não atípicas

Objetivo: Avaliar o percentual etiológico das pneumonias atípicas tratadas ambulatorialmente. Identificar os fatores epidemiológicos, clínicos e radiológicos que permitam diferenciar pneumonia atípica de não atípica. Métodos: Os pacientes foram submetidos a avaliação clínica, radiológica, coleta de escarro para estudo pelo método de Gram e sangue para testes sorológicos, incluindo Legionella pneumophila, Chlamydia sp, Mycoplasma pneumoniae, vírus Influenza A e Influenza B, no primeiro dia e 21 dias após inclusão. As radiografias de tórax foram revistas por três observadores independentes que desconheciam o quadro clínico. Resultados: Avaliados inicialmente 129 pacientes durante 22 meses. A amostra final para estudo comparativo entre os grupos consistiu de 69 pacientes que tinham em média 37 anos, sendo 46 (67%) homens e 23 (33%) mulheres. O diagnóstico etiológico foi definido em 34 (50%) dos pacientes. Chlamydia sp foi o agente atípico mais freqüente, com 11 (16%) casos, seguido por M. pneumoniae com 7 (10%). Influenza A respondeu por 4 (6%) dos casos e Legionella em 4 (6%) pacientes. Infecções mistas foram evidenciadas, com associação de Chlamydia sp e M. pneumoniae em 5 (7%) casos, Chlamydia sp e Influenza B em um caso e M. pneumoniae e Influenza A em outro. A presença de sintomas respiratórios e achados gerais sugestivos de pneumonia atípica foram comparados entre os grupos e não foram observadas diferenças significantes. A avaliação radiológica realizada por três observadores independentes mostrou discordância entre eles para os tipos de pneumonia. O diagnóstico radiográfico de cada observador comparado com o diagnóstico clínico não mostrou associação significante. Conclusões: A pneumonia causada por agente atípico ocorre em 50% dos pacientes com pneumonia adquirida na comunidade em tratamento ambulatorial. Não é possível distinguir pacientes com pneumonia atípica de pneumonia não atípica. A apresentação clínica e a radiológica são similares nos dois grupos.

The possible role of infections in acute myocardial infarction

Cardiovascular diseases, particularly coronary heart disease (CHD) and myocardial infarction (MI), are among the leading causes for morbidity and mortality in industrialized countries [2, 77]. During the past decades, various clinical or lifestyle risk factors for myocardial infarction such as hyperlipidemia, hypertension, obesity, lack of physical exercise and smoking have been identified. However, it is also recognized that these well-documented risk factors do not sufficiently account for all new cases of myocardial infarction [77]. Many patients with myocardial infarction have only a borderline risk profile or even lack known risk factors. The question arises: What additional risk factors may play a role in the etiology of atherosclerosis and ischemic heart disease?

Evidence of 2 waves of Chlamydia pneumoniae infection in Gävle, Sweden, 1990-96

Chlamydia pneumoniae is a common respiratory tract pathogen. The majority of adults have serological evidence of previous exposure. Most infections are probably asymptomatic or subclinical. Recent studies have implicated C. pneumoniae as a risk factor for the development of cardiovascular disease. It was therefore of interest to study new blood donors collected between the years of 1990 and 1996 for the purpose of delineating the epidemiological situation in the Gävle area of Sweden. Sera from all first time blood donors over a 7 y period were tested for IgG, IgA and IgM antibodies to C. pneumoniae with a microimmunofluorescence test (MIF). Donors were subjectively healthy individuals between 18 and 65 y of age, (913 M, 752 F). Exposure to C. pneumoniae, expressed in terms of specific IgG antibodies in titres of > 1/32, increased for men in 1990-92 and for women in 1990-93. There was a decrease the following year for both sexes, followed by another increase in 1994-95. IgG antibodies in titres of > or = 512, and IgA antibodies in titres of > or = 1/64, were increased in 1990-91 for men and in 1994-96 for both sexes. The prevalence of specific antibodies increased throughout the 7 y period except for women 1995-96. Men had higher antibody titres than women throughout the entire study period. The results indicate that two waves of largely subclinical infection occurred in our area over the years 1990-96.

Chlamydia pneumoniae infection and atherosclerotic coronary disease

BACKGROUND

Previous works have suggested an association between Chlamydia pneumoniae infection and coronary heart disease. We evaluated the prevalence of C. pneumoniae infection in patients with acute myocardial infarction (AMI) and coronary heart disease (CHD).

METHODS AND RESULTS

Ninety-eight patients with AMI, 80 patients with CHD, and 50 control subjects matched for age and sex were investigated. Immunoglobulin (Ig)M, IgG, and IgA antibodies to C pneumoniae were measured by the microimmunofluorescence test. IgM antibodies were not found; IgG positivity was found in 58.2% of the AMI group, 60.0% of the CHD group, and 38% of the control group, whereas for IgA, positivity was found in 33.7%, 43.7%, and 22% of cases in AMI, CHD, and control groups, respectively. Titers indicating reinfection were found in AMI and CHD groups in 6.1% and 10%, respectively, whereas titers indicating chronic infection were found in 14% of the AMI group and 25% of the CHD group. A significant correlation was found between chronic C pneumoniae infection and dyslipidemias in the AMI and CHD groups (P =.003; P =. 0006).

CONCLUSIONS

The results suggest that chronic C pneumoniae infection may be associated with the development of atherosclerotic coronary disease. In our next step, we will test whether antichlamydial antibiotics may help to reduce the risk of atherosclerotic disease.

Immunoglobulin A antibodies against Chlamydia pneumoniae are associated with expansion of abdominal aortic aneurysm

BACKGROUND

The aim of this study was to examine the possible association between the progression of small abdominal aortic aneurysm (AAA) and chronic infection with Chlamydia pneumoniae.

METHODS

Patients from a hospital-based mass screening programme for AAA with annual follow-up (mean 2.7 years) were included. After initial interview, 139 men aged 65-73 years with a small AAA underwent examination and blood sampling. Immunoglobulin (Ig) G and IgA titres against C. pneumoniae were measured by a microimmunofluorescence test.

RESULTS

Some 83 (95 per cent confidence interval 74-93) per cent of the men had an IgA titre of 20 or more, or an IgG titre of 32 or more. Men with an IgA titre of 20 or more had a 48 per cent higher AAA expansion rate than those with a titre of less than 20 (3.1 versus 2.1 mm/year; P < 0.05). Multiple linear and logistic regression analyses showed that an IgA titre of 20 or more was a significant independent predictor of increased AAA expansion, adjusted for known risk factors of expansion. Initial AAA size and serum total cholesterol level were also predictors of expansion.

CONCLUSION

A high proportion of men with a small AAA had signs of chronic infection with C. pneumoniae. Aneurysm progression correlated with evidence of chronic C. pneumoniae infection.

A review of Chlamydia pneumoniae and atherosclerosis

Chlamydia pneumoniae is a Gram-negative obligate intracellular bacterium that causes acute upper and lower respiratory infections. Its distribution is worldwide. Seroepidemiological studies have shown an association between C. pneumoniae and atherosclerosis, and the risk of acute myocardial infarction. Several studies had detected C. pneumoniae in atherosclerotic lesions from coronary and carotid arteries, in abdominal aortic aneurysms (AAA), and in sclerotic aortic valves. One study consistently succeeded in culturing C. pneumoniae from an atherosclerotic lesion, indicating the presence of viable organisms. However, the pathogenicity is unknown, and the significance of detecting the organism is unresolved. In two minor controlled clinical trials, patients with ischaemic heart disease were randomised into antibiotic-treated and placebo groups. Both trials showed a significant reduction in serious endpoints in patients receiving macrolide. Macrolide therapy thus seems to improve the outcome of severe ischaemic heart disease. It is not known whether this is caused by eradicating C. pneumoniae organisms, or by the macrolide's non-specific anti-inflammatory effect. Since both C. pneumoniae and inflammation are found in the AAA wall, it may be considered that macrolide would also improve the outcome of AAA and other diseases related to vascular surgery. In order to confirm this, randomised trials with macrolide therapy are needed, as well as diagnostic methods that can differentiate between individuals who are or are not infected with C. pneumoniae. The latter are needed in order to clarify the impact of the presence of C. pneumoniae and to avoid indiscriminate use of antimicrobials.

Chlamydia pneumoniae and atherosclerosis

OBJECTIVE

To review the literature for evidence that chronic infection with Chlamydia pneumoniae is associated with atherosclerosis and acute coronary syndromes.

DATA SOURCES

MEDLINE and Institute of Science and Information bibliographic databases were searched at the end of September 1998. Indexing terms used were chlamydi*, heart, coronary, and atherosclerosis. Serological and pathological studies published as papers in any language since 1988 or abstracts since 1997 were selected.

DATA EXTRACTION

It was assumed that chronic C pneumoniae infection is characterised by the presence of both specific IgG and IgA, and serological studies were examined for associations that fulfilled these criteria. Pathological studies were also reviewed for evidence that the presence of C pneumoniae in diseased vessels is associated with the severity and extent of atherosclerosis.

DATA SYNTHESIS

The majority of serological studies have shown an association between C pneumoniae and atherosclerosis. However, the number of cases in studies that have reported a positive association when using strict criteria for chronic infection is similar to the number of cases in studies which found no association. Nevertheless, the organism is widely found in atherosclerotic vessels, although it may not be at all diseased sites and is not confined to the most severe lesions. Rabbit models and preliminary antibiotic trials suggest that the organism might exacerbate atherosclerosis.

CONCLUSION

More evidence is required before C pneumoniae can be accepted as playing a role in atherosclerosis. Although use of antibiotics in routine practice is not justified, large scale trials in progress will help to elucidate the role of C pneumoniae.

Etiology of childhood pneumonia: serologic results of a prospective, population-based study

BACKGROUND

To investigate the etiology of pediatric community-acquired pneumonia, we conducted a prospective, population-based study covering the total population <15 years of age (n = 8851) in 4 municipalities in eastern Finland.

MATERIALS AND METHODS

The number of patients was 201; chest radiographs were available for all cases and paired sera for serologic assays were available for >90% of cases. The methods included assays for antibody response to 3 pneumococcal antigens, specific pneumococcal immune complex assays and conventional antibody tests for mycoplasmal, chlamydial and viral infections.

RESULTS

Serologic evidence of specific microbial etiology was obtained in 133 (66%) of the pneumonia patients. Bacterial infection was diagnosed in 102 cases (51%) and viral infection in 51 cases (25%). Streptococcus pneumoniae was the most common agent (57 cases; 28%), followed by Mycoplasma pneumoniae (44; 22%), respiratory syncytial virus (43; 21%) and Chlamydia spp. (29; 14%). Haemophilus influenzae was identified in only 6% and Moraxella catarrhalis in only 3% of the children. More than one specific infection was found in 51 patients (25%). The proportion of pneumococcal cases varied from 24 to 36% by age. Mycoplasma infections were seen mostly in patients > or =5 years and Chlamydia infections in patients > or =10 years of age.

CONCLUSIONS

The results of our prospective, strictly population-based study confirm the importance of S. pneumoniae in the etiology of community-acquired pneumonia in children of all ages. M. pneumoniae and Chlamydia pneumoniae are important from the age of 5 years onwards.

Serological evidence of an association between chlamydial infections and malignant lymphomas

Chronic infections may predispose to malignant growth. Recently, serological markers of chronic Chlamydia pneumoniae infection have been associated with lung cancer. Our aim was to study the possible association between chronic chlamydial infections and malignant lymphomas. The present case-control study involved 72 patients with lymphoma (31 females and 41 males) and matched controls. 53 patients had non-Hodgkin's lymphoma (NHL) and 19 had Hodgkin's disease. The sera, collected at the time of diagnosis, were tested for IgG antibodies and immune complexes to C. pneumoniae and C. trachomatis by a microimmunofluorescence method and ELISA and for IgG antibodies and immune complexes to Helicobacter pylori by ELISA. The serological markers suggesting chronic chlamydial infection were associated with malignant lymphoma. The association was most evident for the presence of C. pneumoniae-specific immune complexes in NHL (OR = 7.3, 95% CI 2.2-25) and appeared to be limited to men. No association between H. pylori antibodies or immune complexes and malignant lymphomas could be demonstrated. Our study provides seroepidemiological evidence of an association between chronic chlamydial infections and lymphomas.

Evaluation of PCR, culture, and serology for diagnosis of Chlamydia pneumoniae respiratory infections

We prospectively studied 156 patients with a diagnosis of community-acquired pneumonia requiring admission. Several respiratory specimens were obtained for the detection of Chlamydia pneumoniae by cell culture and PCR. Three serum samples were obtained from each patient. Serological diagnosis of a C. pneumoniae infection was determined by the microimmunofluorescence (MIF) test, the complement fixation (CF) test, and recombinant lipopolysaccharide (LPS) enzyme-linked immunosorbent assay (ELISA; referred to as the rDNA LPS ELISA). Twenty-three patients (15%) had serological results compatible with acute C. pneumoniae infection; nine (39%) of these subjects were C. pneumoniae PCR positive. Twenty-two patients (14%) had positive PCR results without serological evidence of an acute C. pneumoniae infection. An attempt was made to calculate the sensitivities and specificities of the MIF test, rDNA LPS ELISA, and PCR for the diagnosis of chlamydial community-acquired pneumonia. Several "gold standards" were defined. Generally, the sensitivities of the rDNA LPS ELISA and MIF were comparable, while the sensitivity of the CF test was shown to be very low. Independent of the gold standard used, the best PCR results were obtained with nasopharyngeal specimens. However, the predictive value of a positive C. pneumoniae PCR result for patients with community-acquired pneumonia remains unknown and may be low. Although a widely accepted gold standard is still lacking, the rDNA LPS ELISA may currently be the preferred tool for diagnosing acute respiratory Chlamydia infections in routine clinical practice. However, the MIF test remains the method of choice for determining the prevalence of C. pneumoniae infections in a given community.

Chlamydia pneumoniae in children attending day-care centers in Gävle, Sweden

BACKGROUND

The epidemiology of Chlamydia pneumoniae in healthy children has not been established.

METHODS

This investigation used polymerase chain reaction (PCR) to study the epidemiology of C. pneumoniae in presumed healthy children. Four hundred fifty-three children and 142 personnel at 9 day-care centers were investigated for carriage of C. pneumoniae. Children found to be positive by PCR were also investigated with serology, and their family members were tested with PCR.

RESULTS

One hundred and three (22.7%) children had a positive PCR, as had 33 (23.2%) personnel. Fourteen percent of the children younger than 3 years had a positive PCR test compared with 26% of the older children (P < 0.01). No correlation was found between respiratory symptoms and carriage of C. pneumoniae. Mothers were more often positive in the PCR test as compared with fathers (relative risk, 2.59; 95% confidence interval, 1.16 to 5.78). Antibodies to C. pneumoniae were found in 27 of 97 PCR-positive children; only 2 of whom were younger than 3 years.

CONCLUSION

C. pneumoniae can be commonly found in young children attending day care. Most of the youngest children did not develop specific antibodies. Children may have subclinical infections with C. pneumoniae. The organism seems to be easily communicable among individuals living in close proximity.

Symptoms of chronic bronchitis and the risk of coronary disease

BACKGROUND

Experimental and epidemiological studies show a positive association between coronary disease and various infections in different organs, both viral and bacterial and both acute and chronic. Most attention has been paid to dental infections and infections in the respiratory tract. We have studied how chronic respiratory infection predicts coronary disease.

METHODS

We defined chronic respiratory infection by the occurrence of symptoms of chronic bronchitis. We also analysed whether any association with coronary disease incidence and mortality is independent of the known major cardiovascular risk factors and whether it is similar among persons in different occupations. Our cohort study was a 13-year follow-up of 19,444 randomly selected eastern Finnish men and women born between 1913 and 1947 and examined in either 1972 or 1977.

FINDINGS

During follow-up, there were 1419 first coronary events, either fatal or non-fatal, and 614 coronary deaths. Among men, the age-adjusted and study-year-adjusted risk ratio of long lasting-symptoms of chronic bronchitis (during as much as 3 months in a year) was 1.52 (95% CI 1.33-1.75) for coronary disease and 1.74 (CI 1.43-2.11) for coronary death. Among women the risk ratios were 1.38 (1.07-1.78) and 1.49 (0.98-2.27), respectively. Inclusion of smoking, serum cholesterol, and systolic blood pressure into the models decreased risk ratios to 1.36 (1.17-1.56) and 1.55 (1.26-1.90) in men and to 1.34 (1.04-1.74) and 1.41 (0.92-2.16) in women, respectively. The risk of coronary disease associated with the symptoms of chronic bronchitis was similar among blue-collar and white-collar workers but the association was not found among farmers.

INTERPRETATION

Symptoms of chronic bronchitis predicted the risk of coronary disease independently from the known major cardiovascular risk factors. If the observed association is causal, prevention and improved management of chronic infections may have played a role in the decrease in coronary disease mortality observed in eastern Finland in the past two decades.

Detection and widespread distribution of Chlamydia pneumoniae in the vascular system and its possible implications

AIMS

To attempt to detect Chlamydia pneumoniae DNA in atheromatous vascular tissue.

METHODS

A modification of an existing polymerase chain reaction (PCR) assay and immunofluorescence staining with a monoclonal antibody directed against C pneumoniae were used to detect C pneumoniae. Specimens from 32 patients undergoing abdominal aortic aneurysm repair were examined. Vascular tissue, ostensibly normal, from six liver transplant donors was also examined for comparison. Altogether, 43 vessels from these 38 subjects (age range 36-85 years) were examined.

RESULTS

C pneumoniae was detected in 11 (44%) of 25 aortas, five (55%) of nine iliac arteries, two (40%) of five femoral arteries, and one of two iliac veins. Immunofluorescence staining supported positive PCR results in three of 12 cases in which it was used. Overall, C pneumoniae was detected in the arteries of 14 (44%) of the patients undergoing vascular surgery and three (50%) of the donors.

CONCLUSIONS

This study is the first in the UK in which C pneumoniae organisms have been found in atherosclerotic vessels and the tendency for the organisms to be present most often in such vessels exhibiting chronic inflammatory changes suggests that a search for them in various forms of arteritis may also be rewarding.

Survival of Chlamydia pneumoniae following contact with various surfaces

OBJECTIVE: In this study, the survival and recovery of Chlamydia pneumoniae (Cp) strains TW-183, AR-39, AR-388 and CWL-029 were measured after inoculation on glass, stainless steel, FormicaR laminate, paper, fabric and human skin. METHODS: Inoculum in throat washes from healthy volunteers was applied to each surface. Samples were taken immediately after inoculum application and at specified intervals thereafter to determine infectivity. RESULTS: Infectious Cp was recovered from glass for up to 4 h, from paper and fabric for up to 3 h, from FormicaR laminate for up to 2 h, from stainless steel for up to 60 min and from human skin for up to 30 min. Drying of the inoculated area had no significant effect on the recovery of infectious Cp. Further experiments demonstrated that infectious Cp could be transferred to hands by touching these contaminated surfaces and could be recovered from these hands for up to 3 min. Addition of albumin, surfactant or phosphatidylcholine had no significant effect on the survival of Cp. CONCLUSIONS: These results suggest that contact with contaminated surfaces may be a potential mode of transmission of Cp.