Chlamydia pneumoniae Upsurge at Tertiary Hospital, Lausanne, Switzerland

Chlamydia pneumoniae infection cases have usually accounted for <1.5% of community-acquired respiratory tract infections. Currently, Lausanne, Switzerland is experiencing a notable upsurge in cases, with 28 reported within a span of a few months. This upsurge in cases highlights the need for heightened awareness among clinicians.

Purification, crystallization and preliminary crystallographic analysis of Chlamydophila pneumoniae AP endonuclease IV

Base excision is a crucial DNA repair process mediated by endonuclease IV in nucleotide excision. In Chlamydia pneumoniae, CpendoIV is the exclusive AP endonuclease IV, exhibiting DNA replication error-proofreading capabilities, making it a promising target for anti-chlamydial drug development. Predicting the structure of CpendoIV, molecular docking with DNA was performed, analyzing complex binding sites and protein surface electrostatic potential. Comparative structural studies were conducted with E. coli EndoIV and DNA complex containing AP sites.CpendoIV was cloned, expressed in E. coli, and purified via Ni-NTA chelation and size-exclusion chromatography. Low NaCl concentrations induced aggregation during purification, while high concentrations enhanced purity.CpendoIV recognizes and cleaving AP sites on dsDNA, and Zn2+ influences the activity. Crystallization was achieved under 8% (v/v) Tacsimate pH 5.2, 25% (w/v) polyethylene glycol 3350, and 1.91 Å resolution X-ray diffraction data was obtained at 100 K. This research is significant for provides a deeper understanding of CpendoIV involvement in the base excision repair process, offering insights into Chlamydia pneumoniae.

Concurrent acute sensorimotor axonal neuropathy and disseminated encephalitis associated with Chlamydia pneumoniae in an adult patient with anti-MOG and anti-sulfatide antibodies: a case report

Acute disseminated encephalomyelitis and Guillain-Barré syndrome refer to post-infectious or post-vaccination inflammatory demyelinating disorders of central and peripheral nervous system, respectively. We report the case of a 60-year-old male patient presenting with irritability, gait difficulty, asymmetric quadriparesis (mostly in his left extremities), distal sensory loss for pain and temperature in left limbs, and reduced tendon reflexes in his upper limbs and absent in his lower limbs, following an upper respiratory tract infection, 3 weeks earlier. Brain magnetic resonance imaging revealed abnormal T2 signal and peripherally enhancing lesions in hemispheres, brainstem, and cerebellum. Nerve conduction studies were compatible with acute motor and sensory axonal neuropathy. Serology revealed positive IgM and IgG antibodies for Chlamydia pneumoniae, and he also tested positive for myelin oligodendrocyte glycoprotein (MOG) and sulfatide antibodies. Treatment with intravenous immunoglobulin and methylprednisolone led to clinical and radiological recovery within weeks. Even though several cases of combined central and peripheral demyelination have been reported before, it is the first case report with seropositive anti-sulfatide and anti-MOG acute sensorimotor axonal neuropathy and disseminated encephalitis associated with C. pneumoniae.

Potential co-infection of influenza A, influenza B, respiratory syncytial virus, and Chlamydia pneumoniae: a case report with literature review

The occurrence of a co-infection involving four distinct respiratory pathogens could be underestimated. Here, we report the case of a 72-year-old woman who presented to a community hospital with a cough productive of sputum as her main clinical manifestation. Antibody detection of common respiratory pathogens revealed potential co-infection with influenza A, influenza B, respiratory syncytial virus, and Chlamydia pneumoniae. We treated her with 75 mg oseltamivir phosphate administered orally twice daily for 5 days, 0.5 g azithromycin administered orally for 5 days, and 0.3 g acetylcysteine aerosol inhaled twice daily for 3 days. The patient showed a favorable outcome on the eighth day after early diagnosis and treatment. Since co-infection with these four pathogens is rare, we performed an extensive PubMed search of similar cases and carried out a systematic review to analyze the epidemiology, clinical manifestations, transmission route, susceptible population, and outcomes of these four different pathogens. Our report highlights the importance for general practitioners to be vigilant about the possibility of mixed infections when a patient presents with respiratory symptoms. Although these symptoms may be mild, early diagnosis and timely treatment could improve outcomes. Additionally, further research is warranted to explore the potential influence of SARS-CoV-2 infection on the co-occurrence of multiple respiratory pathogens.

A Functional Yeast-Based Screen Identifies the Host Microtubule Cytoskeleton as a Target of Numerous Chlamydia pneumoniae Proteins

Bacterial pathogens have evolved intricate ways to manipulate the host to support infection. Here, we systematically assessed the importance of the microtubule cytoskeleton for infection by Chlamydiae, which are obligate intracellular bacteria that are of great importance for human health. The elimination of microtubules in human HEp-2 cells prior to C. pneumoniae infection profoundly attenuated the infection efficiency, demonstrating the need for microtubules for the early infection processes. To identify microtubule-modulating C. pneumoniae proteins, a screen in the model yeast Schizosaccharomyces pombe was performed. Unexpectedly, among 116 selected chlamydial proteins, more than 10%, namely, 13 proteins, massively altered the yeast interphase microtubule cytoskeleton. With two exceptions, these proteins were predicted to be inclusion membrane proteins. As proof of principle, we selected the conserved CPn0443 protein, which caused massive microtubule instability in yeast, for further analysis. CPn0443 bound and bundled microtubules in vitro and co-localized partially with microtubules in vivo in yeast and human cells. Furthermore, CPn0443-transfected U2OS cells had a significantly reduced infection rate by C. pneumoniae EBs. Thus, our yeast screen identified numerous proteins encoded using the highly reduced C. pneumoniae genome that modulated microtubule dynamics. Hijacking of the host microtubule cytoskeleton must be a vital part of chlamydial infection.

Assessment of the Association of Chlamydia e pneumoniae Infection with Lung Cancer in a Moroccan Patients' Cohort

BACKGROUND

Chlamydia pneumoniae (C. pneumoniae) is a respiratory pathogen associated with chronic inflammatory and its detection in human lung cancer suggests its involvement in cancerogenesis. Our study aimed to evaluate the association between C. pneumoniae  infection and Lung Cancer disease in Moroccans patients and control cohorts, through a molecular investigation.

METHODS

The study comprised 42 lung cancer patients and 43 healthy controls. All participants provided demographics, Clinical, and Toxic behaviors datas, and a peripheral blood sample for testing, a Nested Polymerase Chain Reaction (PCR) was performed for C. pneumoniae Deoxyribonucleic acid (DNA) detection. Statistical analysis was performed using IBM®SPSS®software.

RESULTS

Positive Nested PCR results for cases and controls were respectively 33.3% and 4.7%, there by  significant difference between cases and controls   infection was identified (p <0.05). Data analysis also showed that tobacco could act synergically with C. pneumoniae infection as a risk factor of lung cancer. In fact a significant difference between patients and controls was shown for tobacco and alcohol use (p < 0.05).

CONCLUSION

C. pneumoniae infection is potentially associated with primary Lung cancer in the Moroccan population and has combined effects with Tabaco consumption.

Atypical Pathogens in Adult Community-Acquired Pneumonia and Implications for Empiric Antibiotic Treatment: A Narrative Review

Atypical pathogens are intracellular bacteria causing community-acquired pneumonia (CAP) in a significant minority of patients. Legionella spp., Chlamydia pneumoniae and psittaci, Mycoplasma pneumoniae, and Coxiella burnetii are commonly included in this category. M. pneumoniae is present in 5-8% of CAP, being the second most frequent pathogen after Streptococcus pneumoniae. Legionella pneumophila is found in 3-5% of inpatients. Chlamydia spp. and Coxiella burnetii are present in less than 1% of patients. Legionella longbeachae is relatively frequent in New Zealand and Australia and might also be present in other parts of the world. Uncertainty remains on the prevalence of atypical pathogens, due to limitations in diagnostic means and methodological issues in epidemiological studies. Despite differences between CAP caused by typical and atypical pathogens, the clinical presentation alone does not allow accurate discrimination. Hence, antibiotics active against atypical pathogens (macrolides, tetracyclines and fluoroquinolones) should be included in the empiric antibiotic treatment of all patients with severe CAP. For patients with milder disease, evidence is lacking and recommendations differ between guidelines. Use of clinical prediction rules to identify patients most likely to be infected with atypical pathogens, and strategies of narrowing the antibiotic spectrum according to initial microbiologic investigations, should be the focus of future investigations.

Serostatus and Epidemiological Characteristics for Atypical Pneumonia Causative Bacteria among Healthy Individuals in Medina, Saudi Arabia, a Retrospective Study

Background: Community-acquired atypical pneumonia is generally a mild and self-limiting infection. Still, it may lead to hospitalization and progressive clinical complications in some cases, particularly among the elderly and individuals with chronic diseases. Chlamydia pneumoniae, Legionella pneumophila, and Mycoplasma pneumoniae are the community’s main causative agents of atypical pneumonia. However, most published studies evaluated their incidence in the hospital setting, and little is known about their prevalence among healthy individuals. This work aims to assess the seroprevalence of these bacteria among healthy people to determine the status of immunity against these bacteria in the community. Methodology: Two hundred and eighty-three serum samples from a multicenter in Medina, Saudi Arabia, were collected in this study. Serum samples were subjected to indirect enzyme-linked immunosorbent assays (ELISAs) to detect IgG antibodies against C. pneumoniae, L. pneumophila, and M. pneumoniae to investigate the seroprevalence of these bacteria and their distribution among different genders and age groups of healthy people. Results: IgG seropositivity for at least one of the three atypical pneumonia-causative bacteria occurred in 85.8% (n= 243/283) of the sample population. IgG seropositivity for C. pneumoniae occurred in 80.6% (228/283) of the population, followed by 37.5% for L. pneumophila and 23% for M. pneumoniae (66/283). In addition, the IgG seropositivity rates for the three bacteria were observed predominantly among male participants. Furthermore, no significant difference in IgG seropositivity distribution occurred between different age groups of healthy people for C. pneumoniae, L. pneumophila and M. pneumoniae. Conclusions: The current study found that C. pneumoniae, L. pneumophila, and M. pneumoniae tended to be highly prevalent among healthy people and more common among males than females. Additionally, their pattern of distribution among healthy individuals seemed to be predominant among young adults (aged 20−40 years), which differs from their predominant distribution among elderly patients in hospital settings (>50 years).

Does the asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS) exist? A narrative review from epidemiology and practice

Asthma and chronic obstructive pulmonary disease (COPD) have traditionally been approached as separate entities that must be researched and treated separately. There is growing recognition, however, that a substantial proportion of patients with obstructive lung disease have characteristics of both asthma and COPD (termed the asthma-COPD overlap syndrome (ACOS)). Lung disease experts have difficulty defining ACOS, and many still resist accepting the possibility that asthma and COPD may be linked. It is likely that practicing clinicians may be equally confused about how to identify and treat ACOS. This narrative review aims to clarify concepts of ACOS definition, argues that the best way to understand ACOS is to view the chronic lung disease process longitudinally rather than cross-sectionally, and presents evidence that ACOS can be the end result of the natural history of severe asthma. The review also points out the serious gaps in knowledge regarding therapy for ACOS and presents emerging data supporting the intracellular respiratory pathogen Chlamydia pneumoniae as a possible common etiologic agent in severe asthma and ACOS.

Role of Intracellular Pulmonary Pathogens during SARS-CoV-2 Infection in the First Pandemic Wave of COVID-19: Clinical and Prognostic Significance in a Case Series of 1200 Patients

Background: Since 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic (COVID-19) has caused millions of deaths worldwide and is the second most serious pandemic after the Spanish flu. Despite SARS-CoV-2 infection having a dominant effect on morbidity and life-threatening outcomes, the role of bacterial co-infection in patients with COVID-19 is poorly understood. The present study aimed to verify the existence of bacterial co-infections and their possible role as cofactors worsening COVID-19-related clinical manifestations. Methods: All patients with suspected SARS-CoV-infection, hospitalised in COVID-19 wards at the Sant'Anna University Hospital of Ferrara, were retrospectively included in this single-centre study and their specific bacterial serologies were assessed. Univariate and logistic regression analyses were performed. Results: A total of 1204 individual records were retrieved. Among them, 959 were excluded because of a negative nasopharyngeal swab or missing data; of the eligible 245 patients, 51 were co-infected. Compared to patients with SARS-CoV-2 infection alone, those with Chlamydia pneumoniae or Mycoplasma pneumoniae co-infections had worse respiratory/radiological features and more intensive care unit admissions. However, the co-infection did not result in a higher mortality rate. Conclusions: The present study, comparing clinical, laboratory and radiological findings between patients with COVID-19 vs. those with co-infections (C. pneumoniae or M. pneumoniae) showed that, on admission, these features were worse in co-infected patients, although the mortality rate did not differ between the two groups.

Chlamydia pneumoniae infections and development of lung cancer: systematic review

Background

Chlamydia pneumoniae is an obligate intracellular pathogen and is a common cause of human respiratory diseases, including pneumonia. It has been already known to have a causal relationship with some chronic diseases such as chronic obstructive pulmonary disease, asthma, and atherosclerotic cardiovascular diseases. In this review, we aim to find out the association between C. pneumoniae infection and lung cancer.

Methods

This is a systematic review on C. pneumoniae infection and the development of lung cancer, based on published articles consolidated from PubMed and Google Scholar on the topic.

Results

Out of 46 articles, 27 were selected and screened through the process. Twenty-four articles positively supported the hypothesis with one animal model, while 3 of them were negatively supportive. Several proposed mechanisms explain the pathogenesis with some knowledge gaps.

Conclusion

Although some studies showed an association between C. pneumoniae infection and lung cancer, whether the C. pneumoniae infection is an individual risk factor for lung cancer is still debatable. And it needs further experimental studies on both humans and animals with large observational studies to better understand the association between C. pneumoniae infection and lung cancer.

Chlamydia pneumoniae is Prevalent in Symptomatic Coronary Atherosclerotic Plaque Samples Obtained From Directional Coronary Atherectomy, but its Quantity is Not Associated With Plaque Instability: An Immunohistochemical and Molecular Study

Aim

To clarify whether there is any association between the extent of Chlamydia pneumoniae (C. pneumoniae) infection and plaque instability or post-directional coronary atherectomy (DCA) restenosis, we determined the frequency of C. pneumoniae infection and its localization in symptomatic coronary atherosclerotic plaques using specimens obtained from DCA.

Methods and results

Immunohistochemistry (IHC) and real-time polymerase chain reaction (RT-PCR) revealed the existence of C. pneumoniae in all 50 specimens of coronary atherosclerotic plaques obtained by DCA. C. pneumoniae-positive cell ratio determined with IHC or copy numbers of C. pneumoniae DNA detected by RT-PCR did not differ significantly between patients with stable angina pectoris and those with acute coronary syndrome (IHC: 16.4 ± 7.6% vs 18.0 ± 7.1%, P = .42; RT-PCR: no. of cases with high copy numbers 12/25 vs 10/25, P = .78), or between patients with subsequent post-DCA restenosis and those without (IHC: 17.1 ± 8.0% vs 18.0 ± 7.4%, P = .74; RT-PCR: 5/12 vs 10/21, P = 1.00).

Conclusions

C. pneumoniae was highly prevalent in coronary atherosclerotic plaques of patients who underwent DCA. However, the extent of C. pneumoniae infection in coronary atherosclerotic plaques was not associated with plaque instability or post-DCA restenosis.

PPARα/γ signaling pathways are involved in Chlamydia pneumoniae-induced foam cell formation via upregulation of SR-A1 and ACAT1 and downregulation of ABCA1/G1

Chlamydia pneumoniae (Cpn) has been reported to be involved in the pathogenesis of early atherosclerosis by inducing macrophage-derived foam cell formation in the presence of low-density lipoprotein (LDL). However, the biochemical mechanisms underlying Cpn-induced foam cell formation are still not fully elucidated. The present study showed that in LDL-treated THP-1-derived macrophages, Cpn not only upregulated the expression of scavenger receptor A1 (SR-A1) and acyl-coenzyme A: cholesterol acyltransferase 1 (ACAT1), but it also downregulated the expression of ATP binding cassette transporters (ABCA1 and ABCG1) at both the mRNA and protein levels. These processes facilitated cholesterol accumulation and promoted macrophage-derived foam cell formation. Treatment with the peroxisome proliferator-activated receptor (PPAR)-γ agonist rosiglitazone or the PPARα agonist fenofibrate decreased the number of foam cells induced by Cpn, while the PPARγ antagonist GW9662, the PPARα antagonist MK886, or PPARα/γ siRNAs enhanced the effect of Cpn on foam cell formation and gene expression of SR-A1, ACAT1, and ABCA1/G1. Moreover, the PPARγ agonist rosiglitazone reversed the downregulation of CD36 by Cpn, while PPARγ siRNA and the PPARγ inhibitor GW9662 further suppressed CD36 expression. However, the PPARα agonist, inhibitor, and siRNA all showed no effect on CD36 expression. In conclusion, the PPARα and PPARγ pathways are both involved in Cpn-induced macrophage-derived foam cell formation by upregulating SR-A1 and ACAT1 and downregulating ABCA1/G1 expression.

Atypical pneumonia: Pathophysiology, diagnosis, and treatment

Atypical pneumonia is caused by atypical pathogens that are not detectable with Gram stain and cannot be cultured using standard methods. The most common causative organisms of atypical pneumonia are Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species. The therapeutic approach for atypical pneumonias is different than that for typical pneumonia. Typical bacterial pathogens classically respond to β-lactam antimicrobial therapy because they have a cell wall amenable to β-lactam disruption. On the contrary, most atypical pathogens do not have a bacterial cell wall, some are intracellular (e.g., Legionella), and some are paracellular (e.g., M. pneumoniae). To prevent an increase in the number of antimicrobial-resistant strains, the Japanese pneumonia guidelines have proposed a differential diagnosis for typical bacterial pneumonia and atypical pneumonia to select an appropriate antibiotic for the management of mild-to-moderate pneumonia. The guidelines have set up six parameters and criteria based on the clinical symptoms, physical signs, and laboratory data. However, in the elderly individuals and patients with underlying diseases, the differential diagnosis may be difficult or a mixed infection may be latent. Therefore, in these individuals, the administration of a β-lactam drug plus a macrolide or tetracycline, or only fluoroquinolone should be considered from the beginning to cover bacterial and atypical pneumonia.

Chlamydia pneumoniae and Helicobacter pylori infections and immunological profile of community-dwelling older adults

Chronic bacterial infections are associated with changes in the immunosenescence process and immunological biomarkers can assist in monitoring these changes. The identification of this immunological profile is important because Chlamydia pneumoniae (C. pneumoniae) and Helicobacter pylori (H. pylori) infections are important factors of morbidity and mortality among the older adults. This study aimed to identify changes in the immunological profile in the presence of C. pneumoniae and H. pylori infections among community-dwelling older adults. This is a cross-sectional study that used data from 1432 participants from the Bambuí Cohort Study of Aging, Minas Gerais, Brazil. The presence of immunoglobulin G (IgG) for C. pneumoniae and H. pylori was considered a dependent variable and assessed in the participants' serum using the enzyme-linked immunosorbent assay (ELISA). In assessing the immunological profile, the following inflammatory markers were considered: CXCL8, CXCL9, CXCL10, CCL2, CCL5, IL-1β, IL-6, IL-10, IL-12, TNF, and CRP. Associations were assessed by logistic regression, estimating odds ratios and confidence intervals (95%) using the Stata® V.13.1 software. The seroprevalence of anti-C. pneumoniae and anti-H. pylori antibodies was 55.9% and 70.3%, respectively. While high levels of anti-C. pneumoniae antibodies were associated with higher concentrations of CXCL10 and IL-10, higher levels of IL-1β and IL-6 were inversely associated with the titration of anti-H. pylori antibodies. The results characterize immunological profiles associated with these chronic infections and reinforce the potential effects of biomarkers on infections by these bacteria and on the immunosenescence process.

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.

Association Between Antibiotic Treatment of Chlamydia pneumoniae and Reduced Risk of Alzheimer Dementia: A Nationwide Cohort Study in Taiwan

Background: Chlamydia pneumoniae (CPn) is a common community-acquired pneumonia. In the literature, CPn infection is demonstrated to exhibit an association with Alzheimer dementia (AD). We executed the present nationwide, population-based research with the goal of probing the association of CPn infection and antibiotic therapy with AD risk. Methods: We conducted a cohort study using a database extracted from Taiwan's National Health Insurance Research Database (NHIRD). All medical conditions for each enrolled individuals were categorized using the International Classification of Diseases, ninth Revision classifications. Hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between CPn pneumonia-associated hospitalizations and AD were estimated using Fine and Gray's survival analysis and adjusted for comorbidities. The effects of the antibiotics on the HRs for AD in the patients with CPn pneumonia-associated hospitalization were also analyzed. Results: Our analyses included 6,628 individuals, including 1,657 CPn-infected patients, as well as 4,971 controls matched by age, index date, and sex (1:3). In this study, patients hospitalized for CPn pneumonia exhibited a significantly higher AD risk (adjusted HR = 1.599, 95% CI = 1.284-1.971, p < 0.001). We also noted an association of macrolide use (≥15 days) and fluoroquinolone use (≥15 days) with decreased AD risk. Conclusions: We determined CPn pneumonia to be associated with a relatively high AD risk. The result in this study confirmed the findings from previous literatures, by using a large, nationwide, population-based database. Appropriate macrolide and fluoroquinolone treatment may attenuate this risk.

Multipeptide Assays for Sensitive and Differential Detection of Anti-Chlamydia Trachomatis Antibodies

Detection of anti-Chlamydia trachomatis (Ctr) antibodies is compromised by cross-reactivity and poor sensitivity of classic Ctr-antigens. We discovered 48 strongly reactive peptide antigens of Ctr-specific B-cell epitopes from 21 immunodominant proteins. In this study, we review the utility of peptide assays for diagnosis of Ctr infections. By combining many of these Ctr-specific B-cell epitopes from several proteins in separate or mixed multipeptide assays, they achieved vastly superior assay sensitivity and specificity over standard enzyme-linked immunosorbent assays. Such multipeptide assays eliminate cross-reactivities (false positives) and correct for stochastic gaps in antibody responses (false negatives). More importantly, we developed and validated a novel microarray platform in which hundreds of peptides from many proteins are spotted in a single reaction well. This offers the possibility of high-throughput screening of many candidate peptides for routine serological fingerprinting of Ctr infections. Discovery of optimal sets of antibody responses that associate with clinical pelvic inflammatory disease (PID) may identify diagnostically useful PID biomarker antigens.

Oxidative Stress and Inflammation in SARS-CoV-2- and Chlamydia pneumoniae-Associated Cardiovascular Diseases

Throughout the years, a growing number of studies have provided evidence that oxidative stress and inflammation may be involved in the pathogenesis of infectious agent-related cardiovascular diseases. Amongst the numerous respiratory pathogens, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus responsible for the global ongoing pandemic, and Chlamydia pneumoniae, a widely known intracellular obligate bacteria, seem to have an essential role in promoting reactive oxygen species and cytokine production. The present review highlights the common oxidative and inflammatory molecular pathways underlying the cardiovascular diseases associated with SARS-CoV-2 or C. pneumoniae infections. The main therapeutic and preventive approaches using natural antioxidant compounds will be also discussed.

Atypical Pathogen Distribution in Chinese Hospitalized AECOPD Patients: A Multicenter Cross-Sectional Study

Purpose

The proportion of atypical pathogens in patient with AECOPD within mainland China is unknown. The objectives of this study were to determine the distribution of atypical pathogens among Chinese patients with AECOPD, to evaluate the clinical characteristics of different atypical pathogen infections, and to compare different detection methods for atypical pathogens.

Patients and Methods

Specimens were collected from patients with AECOPD from March 2016 to November 2018 at eleven medical institutions in eight cities in China. Double serum, sputum, and urine samples were obtained from 145 patients. Serological and nucleic acid tests were used to assess for Mycoplasma pneumonia and Chlamydia pneumoniae; serological, urinary antigen, and nucleic acid tests were applied to detect Legionella pneumophila. The clinical characteristics of atypical pathogen-positive and -negative groups were also compared.

Results

The overall positivity rate for Mycoplasma pneumoniae was 20.69% (30/145), with the highest rate being 20.00% (29/145) when determined by passive agglutination.The overall positive rates for Chlamydia pneumoniae and Legionella pneumophila were 29.66% (43/145) and 10.34% (15/145), respectively. The most common serotype of Legionella pneumophila was type 6. The maximum hospitalized body temperature, ratio of eosinophils, C-reactive protein (CRP) level, and procalcitonin (PCT) level of the Mycoplasma pneumoniae-positive group were significantly higher than those of the Mycoplasma pneumoniae-negative group. Patients in the Chlamydia pneumoniae-positive group smoked more, had higher proportions of comorbidities and frequent aggravations in the previous two years than those in the Chlamydia pneumoniae-negative group. Furthermore, the forced expiratory volume in one second to forced vital capacity (FEV₁/FVC) ratio assessment of lung function was higher, and the concentration of arterial blood bicarbonate (HCO₃ ^-) was lower in the Legionella pneumophila-positive group than in the Legionella pneumophila-negative group.

Conclusion

Overall, atypical pathogens play an important role in AECOPD. Regarding the testing method, serological testing is a superior method to nucleic acid testing.

extracts over Chlamydia trachomatis and Chlamydia pneumoniae on different stages of the chlamydial life cycle

Chlamydial infections in humans are widely distributed and are responsible for a variety of acute and chronic diseases. Both Chlamydia trachomatis and Chlamydia pneumoniae can lead to chronic conditions that have been linked to complications and sequelae. This study aimed to develop a culture method in order to detect in vitro antichlamydial activity of different extracts obtained from native Argentinian plants used as antimicrobials in local ethnomedicine and to evaluate their inhibitory activity over Chlamydia trachomatis and Chlamydia pneumoniae growth. The inhibitory activity over different stages of the chlamydial life cycle on cell culture was assessed: the entry, the inclusion developing after entry, and the exponential growth stage. Also, the capability of rendering the cell refractory to chlamydial infection by pre-incubation with the extracts was assayed. Inhibitory activity of water-based and organic-based extracts obtained from Hydrocotyle bonariensis Lam. (Araliaceae), Lithraea molleoides (Vell.) Engl. (Anacardiaceae) and Hybanthus parviflorus (Mutis ex L.f.) Baill. (Violaceae) were tested against five strains of Chlamydia trachomatis (L2/434/BU and four clinical isolates form both neonatal conjunctivitis and adult genital infections, genotypes D, E, and K) and against Chlamydia pneumoniae AR39. The Hydrocotyle bonariensis dichloromethane extract showed a broad inhibitory activity over the exponential growth stage of Chlamydia trachomatis and Chlamydia pneumoniae independently from the chlamydial strain and the cell line. These results suggest a high inhibitory potential on both Chlamydiae species. In order to characterize the Hydrocotyle bonariensis dichloromethane active extract, an ¹H-NMR was performed. The ¹H-NMR characterization showed a spectrum with characteristic signals of the fatty acid moiety of lipids or cerebrosides, volatile phenolics, phytosterols, methyl triterpenes signals, and glucose moiety of the cerebrosides.

Associations of Infectious Agents with Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

The role of infectious agents in the development of Alzheimer's disease (AD) has long been debated, however, uncertainties still persist.

OBJECTIVE

We aimed to illuminate the associations between infectious agents and risk of AD comprehensively.

METHODS

Studies examining the associations between AD and infectious agents were identified through a systematic search of PubMed, Embase, and Cochrane library. A random-effects meta-analysis was conducted. Publication bias was explored using funnel plot.

RESULTS

Fifty-one studies were included in the systematic review, of which forty-seven studies with 108,723 participants and 4,039 AD cases were eligible for meta-analysis. Evidence based on case control studies demonstrated that Chlamydia pneumoniae [odds ratio (OR): 4.39, 95% CI = 1.81-10.67; I2 = 68%)], Human herpes virus-6 (OR: 3.97, 95% CI = 2.04-7.75; I2 = 0%, Epstein-Barr virus (OR:1.45, 95% CI = 1.00-2.08; I2 = 0%), Herpes simplex virus-1 (OR:1.34, 95% CI = 1.02-1.75; I2 = 0%), and the Herpesviridae family (OR:1.41, 95% CI = 1.15-1.74; I2 = 12%) infection were associated with a higher risk of AD. No significant evidence of publication bias was found.

CONCLUSION

These findings strengthened the evidence that infection may play an important role in AD. Additional research is required to determine whether treatment strategies targeting infectious diseases to prevent AD are viable in the future.

Ambroxol Treatment Suppresses the Proliferation of Chlamydia pneumoniae in Murine Lungs

Ambroxol (Ax) is used as a mucolytics in the treatment of respiratory tract infections. Ax, at a general dose for humans, does not alter Chlamydia pneumoniae growth in mice. Therefore, we aimed to investigate the potential anti-chlamydial effect of Ax at a concentration four timed higher than that used in human medicine. Mice were infected with C. pneumoniae and 5-mg/kg Ax was administered orally. The number of recoverable C. pneumoniae inclusion-forming units (IFUs) in Ax-treated mice was significantly lower than that in untreated mice. mRNA expression levels of several cytokines, including interleukin 12 (IL-12), IL-23, IL-17F, interferon gamma (IFN-γ), and surfactant protein (SP)-A, increased in infected mice treated with Ax. The IFN-γ protein expression levels were also significantly higher in infected and Ax-treated mice. Furthermore, the in vitro results suggested that the ERK 1/2 activity was decreased, which is essential for the C. pneumoniae replication. SP-A and SP-D treatments significantly decreased the number of viable C. pneumoniae IFUs and significantly increased the attachment of C. pneumoniae to macrophage cells. Based on our results, a dose of 5 mg/kg of Ax exhibited an anti-chlamydial effect in mice, probably an immunomodulating effect, and may be used as supporting drug in respiratory infections caused by C. pneumoniae.

Seasonality in testing and positive respiratory bacterial infections in the Australian Capital Territory, 1997-2007

Background

Chlamydia pneumoniae (Cp) and Mycoplasma pneumoniae (Myco) bacteria are atypical pathogens that can cause pneumonia and exacerbate underlying conditions such as asthma and chronic obstructive pulmonary disease. In the Australian Capital Territory, there is limited information on how seasonal patterns for positive infections and testing may vary, a gap that has implications for control strategies.

Methods

We examined seasonal patterns of immunoassay results of patients from Canberra Hospital, Australia, who were tested for Cp and/or Myco. Pathology data, collected from August 1997 to March 2007 from 7,275 patients, were analysed with time series additive decomposition and time series regression.

Results

The proportion of positive Cp infections was highest in March and April (autumn) and lowest in June and August (winter). The proportion of positive Myco infections was highest in December and January (summer) and lowest in August (winter), even though testing for the pathogen peaked in winter with a low in summer. Models with a long-term trend and a variable for month were a better fit for the data than the null models for both infections.

Conclusion

We found differences in seasonal patterns of testing and in the proportion of positive infections. These findings suggest that preventative measures for common infections need to account for seasonal testing practices so as to build an accurate picture of temporal changes in these infections.

Development and evaluation of a novel quenching probe PCR (GENECUBE) assay for rapidly detecting and distinguishing between Chlamydia pneumoniae and Chlamydia psittaci

Early detection of the family Chlamydiaceae as pathogens is essential worldwide for the rapid and sufficient management of atypical pneumonia. GENECUBE (TOYOBO) is a novel fully automated gene analyzer capable of amplifying and detecting target DNAs within 50 min. In this study, we developed a new PCR assay with a specific quenching probe (PCR-QC assay) for rapidly distinguishing between Chlamydia pneumoniae (CPN) and Chlamydia psittaci (CPS). The PCR-QC assay enabled us to precisely and simultaneously detect the 2 different types of DNA fragments even in a mixed sample by identifying unique melting temperatures. Next, we examined a total of 300 frozen samples from patients with respiratory tract infection using the PCR-QC assay and the cell culture method as the gold standard. Kappa index for agreement between the PCR-QC assay and the culture method was 0.43 (95% confidential interval (CI): 0.08-0.78). The sensitivity and specificity of the PCR-QC assay were 36.3% (4/11; 95% CI: 10.9-69.2%)) and 99.0% (286/289; 95% CI: 97.0-99.8%), respectively. The samples positive for CPN (n = 13) or CPS (n = 1) by either method were also examined by a conventional PCR TaqMan assay, which produced the same results as those from the PCR-QC assay. Furthermore, the PCR-QC assay using GENECUBE shortened the full detection time for CPN or CPS (within 50 min vs. more than 2 to 3 h) compared with conventional PCR TaqMan assays. Therefore, the new PCR-QC assay system equipped with GENECUBE is useful for rapidly detecting CPN or CPS pathogens in clinical laboratory, and may improve the management of atypical pneumonia.

Licensed Anti-Microbial Drugs Logical for Clinical Trials against Pathogens Currently Suspected in Alzheimer's Disease

There is now considerable evidence that several infectious agents (viruses, bacteria, or parasites) may play a contributing role in the development of Alzheimer's disease (AD). The six primary suspects are herpes viruses, spirochetal bacteria, Chlamydia pneumoniae, Porphyromonas gingivalis, mycobacteria, and toxoplasma parasites. Also, some of the antimicrobial and antiviral agents that are used to treat them have shown promise for AD interventions. I describe this evidence and assert it is now time to accelerate clinical trials of these existing drugs, already federally approved, to determine if such treatments can delay, halt, or reverse AD.

Beneficial Immunomodulatory Effects of Fluticasone Propionate in Chlamydia pneumoniae-Infected Mice

The associations between inhaled corticosteroid (ICS) use and pulmonary infections remains controversial. Chlamydia pneumoniae (C. pneumoniae) accounts for asthma exacerbations; however, there are no data regarding ICS effects on C. pneumoniae infections. Thus, we investigated whether fluticasone propionate (FP) or budesonide (BUD) could affect C. pneumoniae infection in vitro and in vivo, focusing on the possible mechanisms that lead to potential anti-chlamydial outcomes. We performed direct qPCR to detect C. pneumoniae growth in infected, FP-treated, and BUD-treated A549 cells. Furthermore, FP or BUD was administered by inhalation to C. pneumoniae-infected mice. The recoverable C. pneumoniae was determined by indirect immunofluorescence. Expression levels of interferon (IFN)-γ and IFN-γ inducible chemokines were assessed by qPCR. We measured the protein concentrations of IFN-γ and of other cytokines that potentially participate in the anti-chlamydial response by ELISA. We found that FP treatment suppressed Chlamydia growth in A549 cells and in mice. Higher levels of IFN-γ gene expression were observed in FP-treated mice compared to the untreated and BUD-treated mice (p < 0.0001). IFN-γ and anti-chlamydial protein MIG/CXCL9 values were significantly higher after FP inhalation. Collectively, FP, but not BUD, suppressed C. pneumoniae growth in vitro and in vivo, which was likely due to the enhanced IFN-γ related responses.

Chronic infection with Chlamydia pneumoniae in asthma: a type-2 low infection related phenotype

Background

Chlamydia pneumoniae and Mycoplasma pneumoniae have been implicated in the pathogenesis of asthma and are responsible for chronic inflammation when host immune system fails to eradicate the bacteria.

Method

We performed a prospective study on 410 patients who underwent a visit at the asthma clinic of CHU of Liege between June 2016 and June 2018 with serology testing for C. pneumoniae and M. pneumoniae.

Results

65% of our asthmatic population had serum IgA and/or IgG towards C. pneumoniae, while only 12.6% had IgM and/or IgG against M. pneumoniae. Compared to seronegative asthmatics, asthmatics with IgA+ and IgG+ against C. pneumoniae were more often male and older with a higher proportion of patients with smoking history. They received higher doses of inhaled corticosteroids (ICS) and displayed lower FEV₁/FVC ratio, higher RV/TLC ratio and lower conductance. They had higher levels of fibrinogen, though in the normal range and had lower sputum eosinophil counts. Patients with IgA− and IgG+ against C. pneumoniae were older and had higher blood monocyte counts and alpha-1-antitrypsin levels as compared to seronegative patients. Patients with IgM and/or IgG towards M. pneumoniae were more often males than seronegative asthmatics. In a subpopulation of 14 neutrophilic asthmatics with Chlamydia pneumoniae IgA + /IgG + treated with macrolides, we found a significant decrease in blood neutrophils and normalization of sputum neutrophil count but no effect on asthma quality of life and exacerbations.

Conclusion

Positive Chlamydia serologic test is more common than positive Mycoplasma serology. Asthmatics with IgA and IgG against C. pneumoniae have more severe disease with increased airway obstruction, higher doses of ICS, more signs of air trapping and less type-2 inflammation.

The association of Chlamydia pneumoniae infection with atherosclerosis: Review and update of in vitro and animal studies

Previous studies have tended to relate Chlamydia pneumoniae (Cpn) infection to atherosclerosis. However, while serological studies have mostly reinforced this hypothesis, inconsistent and even contradictory findings have been reported in various researches. Recent papers have pointed to the significance of Cpn in atherosclerotic lesions, which are regarded as the initiator and cause of chronic inflammation. This bacterium develops atherosclerosis by phenotypic changes in vascular smooth muscle cells, dysregulation of endothelin-1 in the vascular wall, and releasing pro-inflammatory cytokines from Toll-like receptor-2 (TLR2). Furthermore, Cpn infection, particularly under hyperlipidemic conditions, enhances monocyte adhesion to endothelium; changes the physiology of the host, e.g., cholesterol homeostasis; and activates the Low-density lipoprotein (LDL) receptor, which is the initial step in atherogenesis. On the other hand, it has been reported that Cpn, even without the immune system of the host, has the ability to stimulate arterial thickening. Moreover, there is evidence that Cpn can increase the impact of the classical risk factors such as hyperlipidemia, pro-inflammatory cytokines, and smoking for atherosclerosis. Furthermore, animal studies have shown that Cpn infection can induce atherosclerotic, which alongside hyperlipidemia is a co-risk factor for cardiovascular disease. Although the exact link between Cpn and atherosclerosis has not been determined yet, previous studies have reported possible mechanisms of pathogenesis for this bacterium. Accordingly, investigating the exact role of this infection in causing atherosclerosis may be helpful in controlling the disease.

Co-infection of SARS-CoV-2 with Chlamydia or Mycoplasma pneumoniae: a case series and review of the literature

INTRODUCTION

The novel coronavirus SARS-CoV-2 has spread all over the world causing a global pandemic and representing a great medical challenge. Nowadays, there is limited knowledge on the rate of co-infections with other respiratory pathogens, with viral co-infection being the most representative agents. Co-infection with Mycoplasma pneumoniae has been described both in adults and pediatrics whereas only two cases of Chlamydia pneumoniae have been reported in a large US study so far.

METHODS

In the present report, we describe a series of seven patients where co-infection with C. pneumoniae (n = 5) or M. pneumoniae (n = 2) and SARS-CoV-2 was detected in a large teaching hospital in Rome.

RESULTS AND CONCLUSION

An extensive review of the updated literature regarding the co-infection between SARS-CoV-2 and these atypical pathogens is also performed.

Insights Into a Chlamydia pneumoniae-Specific Gene Cluster of Membrane Binding Proteins

Chlamydia pneumoniae is an obligate intracellular pathogen that causes diseases of the upper and lower respiratory tract and is linked to a number of severe and chronic conditions. Here, we describe a large, C. pneumoniae-specific cluster of 13 genes (termed mbp1-13) that encode highly homologous chlamydial proteins sharing the capacity to bind to membranes. The gene cluster is localized on the chromosome between the highly diverse adhesin-encoding pmp genes pmp15 and pmp14. Comparison of human clinical isolates to the predicted ancestral koala isolate indicates that the cluster was acquired in the ancestor and was adapted / modified during evolution. SNPs and IN/DELs within the cluster are specific to isolates taken from different human tissues and show an ongoing adaptation. Most of the cluster proteins harbor one or two domains of unknown function (DUF575 and DUF562). During ectopic expression in human cells these DUF domains are crucial for the association of cluster proteins to the endo-membrane system. Especially DUF575 which harbors a predicted transmembrane domain is important for binding to the membrane, while presence of the DUF562 seems to be of regulatory function. For Mbp1, founding member of the cluster that exhibits a very limited sequence identity to the human Rab36 protein, we found a specific binding to vesicles carrying the early endosomal marker PtdIns(3)P and the endosomal Rab GTPases Rab11 and Rab14. This binding is dependent on a predicted transmembrane domain with an α-helical / β-strand secondary structure, as the mutant version Mbp1mut, which lacks the β-strand secondary structure, shows a reduced association to PtdIns(3)P-positive membranes carrying Rab11 and Rab14. Furthermore, we could not only show that Mbp1 associates with Rab36, but found this specific Rab protein to be recruited to the early C. pneumoniae inclusion. Detection of endogenous Mbp1 and Mbp4 reveal a colocalization to the chlamydial outer membrane protein Momp on EBs. The same colocalization pattern with Momp was observed when we ectopically expressed Mbp4 in C. trachomatis. Thus, we identified a C. pneumoniae-specific cluster of 13 membrane binding proteins (Mbps) localizing to the bacterial outer membrane system.

The global prevalence of Chlamydia pneumoniae, Helicobacter pylori, Cytomegalovirus and Herpes simplex virus in patients with coronary artery disease: A systematic review and meta-analysis

BACKGROUND AND AIM

Coronary Artery Disease (CAD) is one of the most important causes of death worldwide. The aim of this study was to determine the prevalence of C. pneumoniae, H. pylori, Cytomegalovirus (CMV) and Herpes simplex virus (HSV) in CAD patients based on published serological and molecular studies.

METHODS

A systematic literature search was conducted in Medline (via PubMed), Embase, Scopus and Web of Science databases (1996-2019). Both molecular and serological studies were analyzed using STATA software (Version 14).

RESULTS

145 studies were included for final analysis. We gathered and investigated the prevalence of C. pneumoniae (25.1% [95% confidence interval (CI) 21.5-28.8%]), H. pylori (12.8% [(95% CI) 4.0-22.0%]), CMV (64.4% [(95% CI) 57.7-73.0%]) and HSV (31.8% [(95% CI) 21.5-42.2%]) in CAD patients from the analysis of molecular studies. Additionally, in serological studies, the prevalence of mentioned pathogens were 72.7% [(95% CI) 67.8-77.6%], 63.3% [(95% CI) 60.0-66.5%], 62.2% [(95% CI) 58.0-66.3%] and 34.3% [(95% CI) 23.6-45.1%] respectively.

CONCLUSION

Interestingly, there was only a significant increase in the prevalence of C. pneumoniae and H. pylori in serological studies compared to the reported data from molecular studies, while the prevalence of CMV and HSV were the same in both types of studies.

Chronic wasting associated with Chlamydia pneumoniae in three ex situ breeding facilities for tropical frogs

A number of different Chlamydia spp. have been detected in the class Amphibia with C. pneumoniae being the predominant species involved. Chlamydiae have been linked to mass mortality events, thereby representing significant pathogens that deserve attention with respect to worldwide amphibian decline. We here present six cases of chlamydiosis and asymptomatic chlamydial infections in different frog species from three ex situ amphibian conservation facilities. Clinical signs predominantly characterised by regurgitation, chronic wasting, lethargy and suspended breeding were associated with C. pneumoniae infection. Despite various treatment regimens, it was not possible to clear infections. However, intra vitam diagnostics succeeded from skin, faeces and urine for the first time.

Super-Resolution Fluorescence Microscopy Reveals Clustering Behaviour of Chlamydia pneumoniae's Major Outer Membrane Protein

Chlamydia pneumoniae is a Gram-negative bacterium responsible for a number of human respiratory diseases and linked to some chronic inflammatory diseases. The major outer membrane protein (MOMP) of Chlamydia is a conserved immunologically dominant protein located in the outer membrane, which, together with its surface exposure and abundance, has led to MOMP being the main focus for vaccine and antimicrobial studies in recent decades. MOMP has a major role in the chlamydial outer membrane complex through the formation of intermolecular disulphide bonds, although the exact interactions formed are currently unknown. Here, it is proposed that due to the large number of cysteines available for disulphide bonding, interactions occur between cysteine-rich pockets as opposed to individual residues. Such pockets were identified using a MOMP homology model with a supporting low-resolution (~4 Å) crystal structure. The localisation of MOMP in the E. coli membrane was assessed using direct stochastic optical reconstruction microscopy (dSTORM), which showed a decrease in membrane clustering with cysteine-rich regions containing two mutations. These results indicate that disulphide bond formation was not disrupted by single mutants located in the cysteine-dense regions and was instead compensated by neighbouring cysteines within the pocket in support of this cysteine-rich pocket hypothesis.

The relationship between Chlamydia pneumoniae infection and CD4/CD8 ratio, lymphocyte subsets in middle-aged and elderly individuals

Chlamydia pneumoniae (C. pneumoniae) is a common respiratory pathogen associated with many inflammatory diseases. There are few data concerning the lymphocyte subsets in middle-aged and elderly individuals with C. pneumoniae infection. A total of 191 patients were included in this study. The study population was categorized into the middle-aged group (40-64 years old) and the elderly group (65-89 years old). Lymphocyte subsets in peripheral blood were examined with multi-colored flow cytometry. Immunological monitoring included lymphocyte subsets, C. pneumoniae IgG and IgM serology. In the middle-aged group, 69.83% individuals presented IgG positivity, which was associated with the inverted CD4/CD8 ratio. Individuals with C. pneumoniae IgG positivity also presented an increased percentage of CD8⁺CD28^- cells and a decreased CD4/CD8 ratio when compared to weakly-positive individuals. In the elderly group, C. pneumoniae IgG positivity was associated with a significant increase in the percentage of CD3⁺CD56⁺CD45⁺ (NKT) cells. In conclusion, altered lymphocyte homeostasis was shown in middle-aged individuals with C. pneumoniae IgG positivity. The senescent phenotypes of T cells might be associated with C. pneumoniae infection in middle-aged individuals.

Chlamydia pneumoniae infection in patients hospitalised for community-acquired pneumonia in Southern Jordan

Purpose

Chlamydia pneumoniae is associated with human respiratory diseases. Few reports examined the involvement of this bacterium in community-acquired pneumonia (CAP) in Jordan. This study investigates for the first time the role of C. pneumoniae in the establishment of CAP among nationals residing the southern part of Jordan.

Materials and Methods

Nasopharyngeal and sera samples were collected from 70 hospitalised CAP patients and 63 healthy controls from Al-Karak Governorate and examined using the microimmunofluorescence and polymerase chain reaction techniques. The overall prevalence of C. pneumoniae infection was estimated by detecting the chlamydial immunoglobulin G (IgG) antibodies at a titre of 1:16. Rate of acute infection was estimated by detecting chlamydial DNA in nasopharyngeal samples and IgG and IgM at titres of 1:512 and 1:16, respectively.

Results

A higher overall seroprevalence of C. pneumoniae IgG was detected in CAP patients than controls (44.3% vs. 30.2%). The rate of acute infection in the entire CAP patients, based on IgG titre of 1:512, was 7.14% compared to 1.58% in the controls. Approximately, three-fold increase in the rate of acute infection was observed in CAP cases, seropositive at IgG titre of 1:16, compared to seropositive controls (16.1% vs. 5.3%). Interestingly, chlamydial IgM antibodies were detectable in 27.1% compared to only 3.2% of the controls. The presence of chlamydial nucleic acids was confirmed in 40% of CAP patients and in 7.9% of controls.

Conclusions

The present findings clearly suggest a role of C. pneumoniae in the aetiology of CAP in Southern Jordan. However, coinfections with other respiratory pathogens should not be excluded.

Opsonophagocytosis of Chlamydia pneumoniae by Human Monocytes and Neutrophils

The human respiratory tract pathogen Chlamydia pneumoniae, which causes mild to severe infections, has been associated with the development of chronic inflammatory diseases. To understand the biology of C. pneumoniae infections, several studies have investigated the interaction between C. pneumoniae and professional phagocytes. However, these studies have been conducted under nonopsonizing conditions, making the role of opsonization in C. pneumoniae infections elusive. Thus, we analyzed complement and antibody opsonization of C. pneumoniae and evaluated how opsonization affects chlamydial infectivity and phagocytosis in human monocytes and neutrophils. We demonstrated that IgG antibodies and activation products of complement C3 and C4 are deposited on the surface of C. pneumoniae elementary bodies when incubated in human serum. Complement activation limits C. pneumoniae infectivity in vitro and has the potential to induce bacterial lysis by the formation of the membrane attack complex. Coculture of C. pneumoniae and freshly isolated human leukocytes showed that complement opsonization is superior to IgG opsonization for efficient opsonophagocytosis of C. pneumoniae in monocytes and neutrophils. Neutrophil-mediated phagocytosis of C. pneumoniae was crucially dependent on opsonization, while monocytes retained minor phagocytic potential under nonopsonizing conditions. Complement opsonization significantly enhanced the intracellular neutralization of C. pneumoniae in peripheral blood mononuclear cells and neutrophils and almost abrogated the infectious potential of C. pneumoniae In conclusion, we demonstrated that complements limit C. pneumoniae infection in vitro by interfering with C. pneumoniae entry into permissive cells by direct complement-induced lysis and by tagging bacteria for efficient phagocytosis in both monocytes and neutrophils.

Naked-Eye Enumeration of Single Chlamydia pneumoniae Based on Light Scattering of Gold Nanoparticle Probe

Chlamydia pneumoniae is a spherical zoonotic pathogen with a diameter of ∼200 nm, which can lead to a wide range of acute and chronic diseases in human body. Early and reliable on-site detection of C. pneumoniae is the key step to control the spread of the pathogen. However, the lack of a current technology with advantages of rapidity, ultrasensitivity, and convenience limits the implementation of traditional techniques for on-site detection of C. pneumoniae. Herein, we developed a naked-eye counting of C. pneumoniae based on the light scattering properties of gold nanoparticle (GNP) under dark-field microscopy (termed "GNP-labeled dark-field counting strategy"). The recognition of single C. pneumoniae by anti-C. pneumoniae antibodies-functionalized GNP probes with size of 15 nm leads to the formation of wreath-like structure due to the strong scattered light resulted from hundreds of GNP probes binding on one C. pneumoniae under dark-field microscopy. Hundreds of GNP probes can bind to the surface of C. pneumoniae due to the high stability and specificity of the nucleic acid immuno-GNP probes, which generates by the hybridization of DNA-modified GNP with DNA-functionalized antibodies. The limit of detection (LOD) of the GNP-labeled dark-field counting strategy for C. pneumoniae detection in spiked samples or real samples is down to four C. pneumoniae per microliter, which is about 4 times more sensitive than that of quantitative polymerase chain reaction (qPCR). Together with the advantages of the strong light scattering characteristic of aggregated GNPs under dark-field microscopy and the specific identification of functionalized GNP probes, we can detect C. pneumoniae in less than 30 min using a cheap and portable microscope even if the sample contains only a few targets of interest and other species at high concentration. The GNP-labeled dark-field counting strategy meets the demands of rapid detection, low cost, easy to operate, and on-site detection, which paves the way for early and on-site detection of infectious pathogens.

Chlamydia pneumoniae immunoglobulin E antibody levels in patients with asthma compared with non-asthma

Chlamydia pneumoniae is an obligate intracellular bacterium that causes respiratory infection in adults and children. There is evidence for an association between atypical bacterial pathogens and asthma pathogenesis. We sought to determine whether past C. pneumoniae infection triggers C. pneumoniae- IgE antibodies (Abs) in asthmatics and non-asthmatics, who had detectable IgG titers. C. pneumoniae IgE Abs were quantified using enzyme immunoassay (EIA). C. pneumoniae IgE Ab levels were higher in asthmatics compared with non-asthmatics. There was no correlation found between total serum IgE levels and specific C. pneumoniae IgE Ab levels. C. pneumoniae infection may trigger IgE-specific responses in asthmatics.

High frequency of Chlamydia pneumoniae and risk factors in children with acute respiratory infection

This study was performed as a contribution for a better understanding of Chlamydia pneumoniae frequency in children with respiratory infections. A total of 416 children were recruited from two clinical centers in Sao Luis, Brazil. Of these patients, 165 children had upper respiratory tract infections (URTI), 150 had community-acquired pneumonia (CAP), and 101 were asymptomatic volunteer children. Clinical and epidemiological data from the participants were recorded. Nasopharyngeal swab samples were collected to extract DNA. C. pneumoniae DNA positivity and copy numbers were obtained by an absolute quantitative real-time PCR method. RESULTS: Positivity for C. pneumoniae DNA was higher in samples from URTI children (38.2%) and from CAP children (18.0%) than in those from the control group (7.9%; p < 0.001). Moreover, C. pneumoniae DNA was denser in children with URTI than in asymptomatic children. Considering the cutoff, the highest value of C. pneumoniae DNA found in asymptomatic children of the 3.98 log10 copies/mL, 8.5% (14/165) of the children with URTI, and 3.3% (5/150) with CAP presented high copy numbers of C. pneumoniae DNA. CONCLUSION: Taken together, these results revealed a high frequency of C. pneumoniae in both children with URTI and CAP.

Infection and atherosclerosis: TLR-dependent pathways

Atherosclerotic vascular disease (ASVD) is a chronic process, with a progressive course over many years, but it can cause acute clinical events, including acute coronary syndromes (ACS), myocardial infarction (MI) and stroke. In addition to a series of typical risk factors for atherosclerosis, like hyperlipidemia, hypertension, smoking and obesity, emerging evidence suggests that atherosclerosis is a chronic inflammatory disease, suggesting that chronic infection plays an important role in the development of atherosclerosis. Toll-like receptors (TLRs) are the most characteristic members of pattern recognition receptors (PRRs), which play an important role in innate immune mechanism. TLRs play different roles in different stages of infection of atherosclerosis-related pathogens such as Chlamydia pneumoniae (C. pneumoniae), periodontal pathogens including Porphyromonas gingivalis (P. gingivalis), Helicobacter pylori (H. pylori) and human immunodeficiency virus (HIV). Overall, activation of TLR2 and 4 seems to have a profound impact on infection-related atherosclerosis. This article reviews the role of TLRs in the process of atherosclerosis after C. pneumoniae and other infections and the current status of treatment, with a view to providing a new direction and potential therapeutic targets for the study of ASVD.

Chronic Inflammatory Diseases at Secondary Sites Ensuing Urogenital or Pulmonary Chlamydia Infections

Chlamydia trachomatis and C. pneumoniae are members of the Chlamydiaceae family of obligate intracellular bacteria. The former causes diseases predominantly at the mucosal epithelial layer of the urogenital or eye, leading to pelvic inflammatory diseases or blindness; while the latter is a major causative agent for pulmonary infection. On top of these well-described diseases at the respective primary infection sites, Chlamydia are notoriously known to migrate and cause pathologies at remote sites of a host. One such example is the sexually acquired reactive arthritis that often occurs at few weeks after genital C. trachomatis infection. C. pneumoniae, on the other hand, has been implicated in an extensive list of chronic inflammatory diseases which include atherosclerosis, multiple sclerosis, Alzheimer’s disease, asthma, and primary biliary cirrhosis. This review summarizes the Chlamydia infection associated diseases at the secondary sites of infection, and describes the potential mechanisms involved in the disease migration and pathogenesis.

Assessment of evidence for or against contributions of Chlamydia pneumoniae infections to Alzheimer's disease etiology

Alzheimer's disease, the most common form of dementia, was first formally described in 1907 yet its etiology has remained elusive. Recent proposals that Aβ peptide may be part of the brain immune response have revived longstanding contention about the possibility of causal relationships between brain pathogens and Alzheimer's disease. Research has focused on infectious pathogens that may colonize the brain such as herpes simplex type I. Some researchers have proposed the respiratory bacteria Chlamydia pneumoniae may also be implicated in Alzheimer's disease, however this remains controversial. This review aims to provide a balanced overview of the current evidence and its limitations and future approaches that may resolve controversies. We discuss the evidence from in vitro, animal and human studies proposed to implicate Chlamydia pneumoniae in Alzheimer's disease and other neurological conditions, the potential mechanisms by which the bacterium may contribute to pathogenesis and limitations of previous studies that may explain the inconsistencies in the literature.

The Association Between Mycoplasma pneumoniae and Chlamydia pneumoniae, a Life-Threatening Condition in Small Children-A Case Report and a Review of the Literature

Mycoplasma pneumoniae (MP) and Chlamydia pneumoniae (CP) are two atypical pathogens that may result in mild, moderate or severe acute respiratory infections. We report the case of a 2 years and 9-month-old male child admitted with prolonged fever, dry cough, and shortness of breath for which he underwent symptomatic treatment. The laboratory tests showed leukocytosis with neutrophilia, anemia, and elevated inflammatory biomarkers and the thoracic radiography revealed pleural effusion raising the suspicion of inferior right pneumonia. Although we the initial evolution was favorable being treated with 3rd class cephalosporin and Oxacillin, on the 8th day of admission the fever and the acute phase reactants levels increased as well as the quantity of the pleural effusion, requiring surgical drainage. We ruled out lung tuberculosis, but we identified positive IgM for both MP and CP. Based on these findings we changed the antibiotic therapy on Levofloxacin for 10 days with favorable evolution. MP and CP are two atypical pathogen that are difficult to be diagnosed due to their slow-growing pattern. Despite their self-limiting feature, the association between them might carry a vital risk in small children, especially in the lack of a proper and timely diagnosis.

Analysis of humoral immune responses to recombinant Chlamydia pneumoniae antigens

OBJECTIVES

Chlamydia pneumoniae is a difficult to diagnose respiratory pathogen. This study was performed to systematically characterize humoral immune responses to selected C. pneumoniae antigens in order to provide novel serodiagnostic perspectives for clinical and epidemiological issues.

METHODS

Based on a literature search, gene library screening, and serological proteome analysis, 15 immunogenic surface-associated, virulence-associated, and hypothetical C. pneumoniae antigens were selected, recombinantly expressed, and lined on a nitrocellulose strip. Specific IgM and IgG reactivity was measured in a total of 172 PCR- and micro-immunofluorescence testing (MIF)-characterized serum samples from patients with respiratory infections. A theoretical model was conceived to approximate a putative course of C. pneumoniae antigen expression and assess the potential of early and late antigens.

RESULTS

While surface antigens performed poorly, the virulence-associated TARP was a reliable antigen for IgM detection, with a sensitivity of 80.0% and a diagnostic specificity of 90.2%. The hypothetical protein YwbM proved powerful for IgG detection with MIF-correlative sensitivities of up to 94.4% and a diagnostic specificity of 95.1%.

CONCLUSIONS

This study provides new insights into antibody profiles to immunogenic proteins in C. pneumoniae infection. The study findings offer antigen candidates for more reliable and standardized serological investigations of C. pneumoniae infections, including studies on seroprevalence and epidemiology.

Chlamydia-Induced Reactive Arthritis: Disappearing Entity or Lack of Research?

PURPOSE OF REVIEW

Recent studies regarding the frequency of Chlamydia-induced reactive arthritis (ReA) are reviewed, with a focus on the question of whether the entity is in fact disappearing or whether it is simply being underdiagnosed/underreported. Epidemiological reports indicate diversity in the frequency of Chlamydia-associated ReA in various parts of the world, with evidence of declining incidence in some regions.

RECENT FINDINGS

The hypothesis that early effective treatment with antibiotics prevents the manifestation of Chlamydia-associated ReA requires further investigation. For clinicians, it is important to remember that ReA secondary to Lymphogranuloma venereum (LGV) serovars L1-L3 of C. trachomatis is probably underestimated due to a limited awareness of this condition, the re-emergence in Western countries of LGV overall, and the present increasingly rare classical inguinal presentation.

Cell-mediated immune response associated with Chlamydia pneumoniae infection in atherosclerotic patients

BACKGROUND

Chlamydia pneumoniae is an obligate intracellular bacterium that activates cell mediated immune responses; several investigations have demonstrated its strong implication in atherosclerosis.

OBJECTIVES

The main objective of our study was to explore the cell-mediated immune response to C. pneumoniae infection in patients with atherosclerosis by evaluating CD14, CD8 and CD4 expression.

METHODS

This investigation involved a total of 27 patients with atherosclerosis and 32 controls, among patients recruited to evaluate the association of C. pneumoniae with atherosclerosis. C. pneumoniae DNA was detected in PBMCs by nested PCR as described in our previous studies. CD4, CD8 and CD14 expression was measured by flow cytometry and data analysis was performed using FlowJo software.

RESULTS

The results revealed an increase in MFI expression of CD4, CD8 and CD14 in Cpn DNA+ subjects among both patients and healthy subject controls (CD4 Cpn DNA⁺ = 829.11 vs. CD4 Cpn DNA^- = 571.14; CD8 Cpn DNA⁺ = 1562 vs. CD8 Cpn DNA^- = 699; CD14 Cpn DNA⁺ = 1513.83 vs. CD14 Cpn DNA^- = 1170.70), with a statistically significant difference (p < 0.05). Furthermore, the comparison of CD4, CD8 and CD14 expression between Cpn DNA+ patients and Cpn DNA+ healthy subject controls showed a statistically significant increase in expression in the former group (p < 0.05).

CONCLUSION

These data provide incentive to further explore the role of C. pneumoniae in stimulating and changing mechanisms of the cell-mediated immune response induced by C. pneumoniae antigens. This may alter immune cell-mediated responses via increased expression of CD4, CD8 and CD14 during inflammation and the development of thrombosis, leading to fatal atherosclerosis.