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Background: In recent years, clinical cases of Chlamydia psittaci pneumonia have gradually increased. Chlamydia psittaci pneumonia can quickly progress to severe pneumonia, leading to respiratory failure. Chlamydia psittaci cannot be detected by commonly used detection methods, leading to difficulties in clinical diagnosis and treatment, which may eventually develop into severe Chlamydia psittaci pneumonia. Therefore, we should improve our diagnostic and treatment capabilities for this disease., Methods: This article retrospectively studied 61 cases of pneumonia from 12 different provinces in China, and classified them into severe pneumonia and non-severe pneumonia. Divided into two groups, with 23 cases of severe pneumonia and 38 cases of non-severe pneumonia. We compared the two groups in terms of imaging, laboratory testing, treatment, prognosis, etc., hoping to provide better explanations and help clinical physicians better diagnose the disease., Results: There is no difference in age, gender, contact history, smoking history, or basic disease between severe and non-severe Chlamydia psittaci pneumonia. The most prominent symptom is fever, with a median body temperature of 39.7 ℃, and other symptoms similar to common respiratory infections. White blood cells and neutrophils may not show significant elevation, but C-reactive protein (CRP) and procalcitonin (PCT) will both show significant elevation, often accompanied by a decrease in arterial oxygen pressure. Some patients may experience liver and kidney dysfunction, but there is no statistically significant difference between the two groups. Doxycycline remains the preferred drug for severe Chlamydia psittaci pneumonia. The imaging mainly shows consolidation and bronchial inflation sign, and may also present with pleural effusion., Conclusions: The imaging of Chlamydia psittaci pneumonia usually shows consolidation with bronchial inflation sign, which can also be manifested as ground glass changes or solid masses. Atypical images are prone to misdiagnosis in the early stages. There are some differences in laboratory examination and imaging between severe pneumonia and non-severe pneumonia, which can help identify severe patients in the early stage. Metagenomic next-generation sequencing (mNGS) played an important role in the diagnosis of all cases in this article. Timely treatment has a good prognosis for the disease, and imaging lesions can be completely absorbed., Competing Interests: Declarations. Ethics approval and consent to participate: We certify that the study was performed in accordance with the Declaration of Helsinki. This study was approved by the Scientific Research Ethics Committee of Beijing Shijitan Hospital affiliated Capital Medical University. The Scientific Research Ethics Committee of Beijing Shijitan Hospital affiliated Capital Medical University approved our study also waived informed consent because this study was retrospective, all information was anonymous, and there was no risk to the subjects. Consent for publication: Not Applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

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.

Chlamydophila Pneumoniae: , a common cause of respiratory tract infections, rarely leads to serious conditions. A 13-year-old boy with serologically confirmed C. pneumoniae infection presented with pneumonia complicated by pericardial and bilateral pleural effusions. He had a large haemorrhagic pericardial effusion from which 1000 ml of fluid was aspirated over 10 days and a right haemorrhagic pleural effusion which required a chest drain and the removal of 700 ml over 5 days. The addition of clarithromycin to ceftriaxone appeared to enhance recovery. As far as we are aware, this is the first report in the English literature of massive haemorrhagic pericardial and pleural effusions in children owing to C. pneumoniae infection.

Psittacosis is a rare disease caused by Chlamydophila psittaci, an intracellular bacteria transmitted by contaminated birds. The clinical and radiological presentations are nonspecific. We describe a case of a 42-year-old woman, with known exposure to birds, who presented to the emergency department with one-week evolution of myalgia, polyarthritis, and respiratory symptoms. At admission, she had fever, respiratory failure, raised inflammatory markers and bilateral interstitial infiltrates at chest radiography. Considering the clinical findings and epidemiological background, we raised the hypothesis of a Chlamydophila psittaci atypical pneumonia that was serologically confirmed. Tetracyclines are the mainstay of treatment and the macrolides are an effective alternative. We highlight the importance of the epidemiological context in the early diagnosis and treatment of this infection.

The in vitro activities of omadacycline, azithromycin, doxycycline, moxifloxacin, and levofloxacin were tested against 15 isolates of Chlamydia pneumoniae The minimum inhibitory concentration at which 90% of the isolates of C. pneumoniae were inhibited by omadacycline was 0.25 μg/ml (range, 0.03 to 0.5 μg/ml)., (Copyright © 2019 American Society for Microbiology.)

Introduction: Chlamydia pneumoniae is an obligatory human pathogen involved in lower and upper airway infections, including pneumonia, bronchitis. Asymptomatic C. pneumoniae carriage is also relatively common. The association of C. pneumoniae infections with the chronic obstructive pulmonary disease (COPD) course is unclear., Objectives: The aim of the study was to investigate the association between chronic C. pneumoniae infection and clinical features of COPD, markers of inflammation and metabolic dysfunction., Patients and Methods: The study included 59 patients with stable COPD who had no, or had ≥2 acute exacerbations during last year. The level of IgA and IgG antibody against C. pneumoniae, IL-6, IL-8, resistin, insulin, adiponectin and acyl ghrelin was measured in serum by enzyme-linked immunosorbent assay (ELISA)., Results: No differences in clinical and functional data were observed between COPD patients without serological features of C. pneumoniae infection and chronic C. pneumoniae infection. The level of anti C. pneumoniae IgA significantly correlated with IL-8, IL-6, resistin concentration in group of frequent exacerbators. IgG level correlated negatively with acetyl ghrelin and body mass index (BMI) in patients without frequent exacerbations, in contrast to frequent COPD exacerbation group where significant correlations between IgG level and BMI was demonstrated. Serum IL-6 correlated positively with resistin and insulin and negatively with adiponectin in group of patients with serological features of chronic C. pneumoniae infection only., Conclusions: Our study showed that chronic C. pneumoniae infection does not influence the clinical course of COPD in the both study groups. Chronic C. pneumoniae infections might be associated with a distinct COPD phenotype that affects metabolic dysfunction.

Background: Chlamydophila pneumoniae is a causative pathogen of lower respiratory tract infection, which generally infects healthy, young people. However, it is often difficult to evaluate acute C. pneumoniae infection using upper respiratory tract specimens and/or sputum samples due to its persistent infection or colonization. The interpretation of frequency of detection of C. pneumoniae seems to be insufficient in community-onset pneumonia. The aim of this study was to evaluate the presence of C. pneumoniae using bronchoalveolar lavage fluid (BALF) samples., Methods: BALF samples from 147 patients with pneumonia were retrospectively evaluated using C. pneumoniae-specific polymerase chain reaction (PCR) primers., Results: None of the samples had positive PCR results for C. pneumoniae using two different sets of specific primers. Single and paired serological analyses were performed in 54 (36.7%) and 37 (25.2%) patients, respectively. These analyses revealed that 1 of 37 (2.7%) patients had a presumptive acute infection with C. pneumoniae, 8 of the 54 (14.8%) patients were suspected of having a C. pneumoniae infection, and 7 of the 37 (18.9%) patients were suspected of having past C. pneumoniae infection. In addition, cultivation and/or 16S rRNA gene sequencing detected Haemophilus influenzae in the presumptive case using the serological method., Conclusions: The results of the present study revealed that C. pneumoniae might be a minor causative agent of community-onset pneumonia according to an evaluation of specimens obtained from the lower respiratory tract., (Copyright © 2017 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.)

Background: Mycoplasma pneumoniae and Chlamydia pneumoniae are atypical pathogens responsible for pneumonia and a leading cause of morbidity and mortality in low income countries. The study objective is to determine the prevalence of this pathogens in Peruvian children with acute respiratory infections., Methods: A consecutive cross-sectional study was conducted in Lima, Peru from May 2009 to September 2010. A total of 675 children admitted with clinical diagnoses of acute respiratory infections were tested for Mycoplasma pneumoniae and Chlamydia pneumoniae detection by polymerase chain reaction (PCR), and clinical symptoms were registered by the attending physician., Results: Mycoplasma pneumonia was detected in 25.19% (170/675) of nasopharyngeal samples and Chlamydia pneumonia in 10.52% (71/675). The most common symptoms in patients with these atypical pathogens were rhinorrhea, cough and fever. A higher prevalence of Mycoplasma pneumoniae cases were registered in summer, between December 2009 and March 2010., Conclusions: Mycoplasma pneumoniae and Chlamydia pneumonia are a significant cause of morbidity in Peruvian children with acute respiratory infections (ARI). Further studies should evaluate the use of reliable techniques such as PCR in Peru in order to avoid underdiagnoses of these atypical pathogens., Competing Interests: The authors have declared that no competing interests exist.

A 61-year-old man was admitted with a 1-week history of influenza-like symptoms during a period of increased influenza virus activity. He soon developed type 2 respiratory failure and became increasingly drowsy. He later suffered a convulsive episode in the intensive care unit (ICU) which self-terminated. Initial clinical findings suggested community-acquired pneumonia and meningoencephalitis. However, a detailed history revealed that he was a pet bird-keeper, which raised a suspicion of ornithosis. Chlamydia psittaci DNA was detected in sputum by PCR. He was started on appropriate antibiotics and made a full recovery. We present this uncommon cause of pneumonia as an example of the importance of accurate history-taking to ensure a correct diagnosis for optimal management., (2016 BMJ Publishing Group Ltd.)

Chronic bacterial infection is implicated in both the development and severity of asthma. The atypical bacteria Mycoplasma pneumoniae and Chlamydophila pneumoniae have been identified in the airways of asthmatics and correlated with clinical features such as adult onset, exacerbation risks, steroid sensitivity, and symptom control. Asthmatic patients with evidence of bacterial infection may benefit from antibiotic treatment directed towards these atypical organisms. Examination of the airway microbiome may identify microbial communities that confer risk for or protection from severe asthma., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Chlamydia trachomatis causes sexually transmitted diseases with infertility, pelvic inflammatory disease and neonatal pneumonia as complications. The duration of urogenital mouse models with the strict mouse pathogen C. muridarum addressing vaginal shedding, pathological changes of the upper genital tract or infertility is rather long. Moreover, vaginal C. trachomatis application usually does not lead to the complications feared in women. A fast-to-perform mouse model is urgently needed to analyze new antibiotics, vaccine candidates, immune responses (in gene knockout animals) or mutants of C. trachomatis. To complement the valuable urogenital model with a much faster and quantifiable screening method, we established an optimized lung infection model for the human intracellular bacterium C. trachomatis serovar D (and L2) in immunocompetent C57BL/6J mice. We demonstrated its usefulness by sensitive determination of antibiotic effects characterizing advantages and limitations achievable by early or delayed short tetracycline treatment and single-dose azithromycin application. Moreover, we achieved partial acquired protection in reinfection with serovar D indicating usability for vaccine studies, and showed a different course of disease in absence of complement factor C3. Sensitive monitoring parameters were survival rate, body weight, clinical score, bacterial load, histological score, the granulocyte marker myeloperoxidase, IFN-γ, TNF-α, MCP-1 and IL-6., (© FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Diagnosis of Chlamydia trachomatis infection in newborns is difficult; however, this diagnosis is performed by cell culture or by detection of IgM antibodies against C. trachomatis. Detection of C. trachomatis DNA in peripheral blood leukocytes using polymer chain reaction (PCR) may be a better tool for the diagnosis of infection by this pathogen., Material and Methods: A total of 44 premature newborns, all weighing less than 2500g, were included in the study. A blood sample and nasopharyngeal lavages were obtained from each newborn. Leukocyte DNA was obtained by phenol-chloroform extraction technique. Detection of C. trachomatis was performed by amplifying the ompA gene using the PCR endpoint. Cell culture tests and the detection of IgM antibodies against C. trachomatis by microimmunofluorescence assay were also performed., Results: Twenty newborns were PCR-positive (45.5%), with this test being significantly associated with the presence of pneumonia (RR=2.28; 95%CI: 1.01 to 5.17; P=.035). The cell culture of nasopharyngeal lavage was positive in only 7 samples and no significant association was observed with any clinical or laboratory data. The titer of IgM antibodies against C. trachomatis associated with PCR-positive was 1:32 (RR=2.74; 95%CI: 1.21 to 6.23; P=.008), however this titer was not associated with the presence of pneumonia., Conclusion: DNA detection in peripheral blood leukocytes could be useful for diagnosis of C. trachomatis infection., (Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.)

Chlamydia pneumoniae causes diseases in humans, including community-acquired pneumonia, bronchitis, and sinusitis. It is also associated with atherosclerosis, coronary heart disease, and hyperlipidemia. In this study, we investigated novel materials with which to develop a sensitive and specific method to identify early C. pneumoniae infection, to allow more effective clinical treatment and prevention. We prepared novel monoclonal antibodies (mAbs) against a recombinant protein equivalent to the immunodominant region of chlamydial protease-like activity factor (CPAF) from C. pneumoniae. The mAbs specifically reacted with the endogenous CPAF antigen of the C. pneumoniae type strain in immunoblotting and indirect immunofluorescence (IIF) assays, but did not react with C. trachomatis type strains or genital secretions from patients with acute C. trachomatis infection. The mAb with the highest titer was used to develop a new IIF assay and enzyme-linked immunosorbent assay (ELISA) to detect the C. pneumoniae antigen in clinical specimens from child patients suspected of pneumonia. The sensitivity, specificity, and concordance rate of the mAb-based IIF and ELISA tests were compared with those of polymerase chain reaction (PCR). Our results show that these mAbs have excellent specificity and may be used to develop new screening tools for the diagnosis of early pediatric pneumonia.

Psittacosis is a zoonotic disease caused by Chlamydophila psittaci. The most common presentation is atypical pneumonia. Three cases of pneumonia of varying severity due to psittacosis are described. All patients had a history of avian contact. The diagnosis was confirmed by molecular detection of Chlamydophila psittaci in respiratory specimens. The cases showed good recovery with doxycycline treatment. Increased awareness of psittacosis can shorten diagnostic delay and improve patient outcomes.

Mycoplasma pneumoniae and Chlamydia spp., which are associated with community-acquired pneumonia (CAP), are difficult to propagate, and can cause clinically indistinguishable disease patterns. During 2011-2012, we used molecular methods to test adult patients in Germany with confirmed CAP for infection with these 2 pathogens. Overall, 12.3% (96/783) of samples were positive for M. pneumoniae and 3.9% (31/794) were positive for Chlamydia spp.; C. psittaci (2.1%) was detected more frequently than C. pneumoniae (1.4%). M. pneumoniae P1 type 1 predominated, and levels of macrolide resistance were low (3.1%). Quarterly rates of M. pneumoniae-positive samples ranged from 1.5% to 27.3%, showing a strong epidemic peak for these infections, but of Chlamydia spp. detection was consistent throughout the year. M. pneumoniae-positive patients were younger and more frequently female, had fewer co-occurring conditions, and experienced milder disease than did patients who tested negative. Clinicians should be aware of the epidemiology of these pathogens in CAP.

Chlamydia pneumoniae (CP) lung infection can induce chronic lung inflammation and is associated with not only acute asthma but also COPD exacerbations. However, in mouse models of CP infection, most studies have investigated specifically the acute phase of the infection and not the longer-term chronic changes in the lungs. We infected C57BL/6 mice with 5 × 10(5) CP intratracheally and monitored inflammation, cellular infiltrates and cytokine levels over time to investigate the chronic inflammatory lung changes. While bacteria numbers declined by day 28, macrophage numbers remained high through day 35. Immune cell clusters were detected as early as day 14 and persisted through day 35, and stained positive for B, T, and follicular dendritic cells, indicating these clusters were inducible bronchus associated lymphoid tissues (iBALTs). Classically activated inflammatory M1 macrophages were the predominant subtype early on while alternatively activated M2 macrophages increased later during infection. Adoptive transfer of M1 but not M2 macrophages intratracheally 1 week after infection resulted in greater lung inflammation, severe fibrosis, and increased numbers of iBALTS 35 days after infection. In summary, we show that CP lung infection in mice induces chronic inflammatory changes including iBALT formations as well as fibrosis. These observations suggest that the M1 macrophages, which are part of the normal response to clear acute C. pneumoniae lung infection, result in an enhanced acute response when present in excess numbers, with greater inflammation, tissue injury, and severe fibrosis.

Q fever is serologically cross-reactive with other intracellular microorganisms. However, studies of the serological status of Mycoplasma pneumoniae and Chlamydophila pneumoniae during Q fever are rare. We conducted a retrospective serological study of M. pneumoniae and C. pneumoniae by enzyme-linked immunosorbent assay (ELISA), a method widely used in clinical practice, in 102 cases of acute Q fever, 39 cases of scrub typhus, and 14 cases of murine typhus. The seropositive (57.8%, 7.7%, and 0%, p<0.001) and seroconversion rates (50.6%, 8.8%, and 0%, p<0.001) of M. pneumoniae IgM, but not M. pneumoniae IgG and C. pneumoniae IgG/IgM, in acute Q fever were significantly higher than in scrub typhus and murine typhus. Another ELISA kit also revealed a high seropositivity (49.5%) and seroconversion rate (33.3%) of M. pneumoniae IgM in acute Q fever. The temporal and age distributions of patients with positive M. pneumoniae IgM were not typical of M. pneumoniae pneumonia. Comparing acute Q fever patients who were positive for M. pneumoniae IgM (59 cases) with those who were negative (43 cases), the demographic characteristics and underlying diseases were not different. In addition, the clinical manifestations associated with atypical pneumonia, including headache (71.2% vs. 81.4%, p=0.255), sore throat (8.5% vs. 16.3%, p=0.351), cough (35.6% vs. 23.3%, p=0.199), and chest x-ray suggesting pneumonia (19.3% vs. 9.5%, p=0.258), were unchanged between the two groups. Clinicians should be aware of the high seroprevalence of M. pneumoniae IgM in acute Q fever, particularly with ELISA kits, which can lead to misdiagnosis, overestimations of the prevalence of M. pneumoniae pneumonia, and underestimations of the true prevalence of Q fever pneumonia.

Objective: Chlamydophila pneumoniae is a common agent of respiratory infections. Severe acute neurological infections are very infrequently linked to this bacterium. We report such a case and give a rapid overview of published cases of acute encephalitis occurring after a respiratory infection due to C. pneumoniae., Patient and Methods: A 12-year-old child without any prior medical history was hospitalized for encephalitis associated to respiratory symptoms., Results: C. pneumoniae DNA was identified by multiplex PCR assay in respiratory secretions and C. pneumoniae IgM and IgG antibodies were assessed in the serum. This bacterium was not detected in CSF, nor was any other pathogen. A macrolide treatment was prescribed for two weeks. The outcome was good without any sequels., Conclusions: This observation correlates to the few similar cases reported in the medical literature. C. pneumoniae must be suggested in the etiological diagnosis of acute encephalitis, notably in a context of respiratory infection, when no more common cause can be identified., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Pneumonia is one kind of common infectious disease, which is usually caused by bacteria, viruses, or fungi. In this paper, we predicted genomic islands in three bacterial pathogens of pneumonia. They are Chlamydophila pneumoniae, Mycoplasma pneumoniae and Streptococcus pneumoniae, respectively. For each pathogen, one clinical strain is involved. After implementing the cumulative GC profile combined with h and BCN index, eight genomic islands are found in three pathogens. Among them, six genomic islands are found to have mobility elements, which constitute a kind of conserved character of genomic islands, and this introduces the possibility that they are genuine genomic islands. The present results show that the cumulative GC profile when combined with h and BCN indexes is a good method for predicting genomic islands in bacteria and it has lower false positive rate than the SIGI method. Specially, three genomic islands are found to contain clusters of genes coding for production of virulence factors and this is useful for research into the pathogenicity of these pathogens and helpful for the treatment of diseases caused by them.

Plasmacytoid dendritic cells (pDCs) are known for their robust antiviral response and their pro-tolerance effects towards allergic diseases and tissue engraftments. However, little is known about the role pDCs may play during a bacterial infection, including pulmonary Chlamydia pneumoniae (CP). In this study, we investigated the role of pDCs during pulmonary CP infection. Our results revealed that depletion of pDCs during acute CP infection in mice results in delayed and reduced lung inflammation, with an early delay in cellular recruitment and significant reduction in early cytokine production in the lungs. This was followed by impaired and delayed bacterial clearance from the lungs which then resulted in a severe and prolonged chronic inflammation and iBALT like structures containing large numbers of B and T cells in these animals. We also observed that increasing the pDC numbers in the lung by FLT3L treatment experimentally results in greater lung inflammation during acute CP infection. In contrast to these results, restimulation of T-cells in the draining lymph nodes of pDC-depleted mice induced greater amounts of proinflammatory cytokines than we observed in control mice. These results suggest that pDCs in the lung may provide critical proinflammatory innate immune responses in response to CP infection, but are suppressive towards adaptive immune responses in the lymph node. Thus pDCs in the lung and the draining lymph node appear to have different roles and phenotypes during acute CP infection and may play a role in host immune responses.

Objective: The Japan Respiratory Society documented a new category of guidelines for nursing and healthcare-associated pneumonia (NHCAP), which is distinct from community acquired pneumonia (CAP). The objective of this study was to determine the epidemiological differences between NHCAP patients in a teaching university hospital and a community hospital. In addition, to clarify the strategy for treatment of NHCAP, we investigated the role of atypical pathogens., Methods: We analyzed 250 NHCAP and 421 CAP cases in a university hospital and 349 NHCAP and 374 CAP cases in a community hospital., Results: Patient age and the incidences of poor general condition were significantly higher in the community hospital compared with those in the university hospital. The distribution and frequency of pathogens, especially multidrug-resistant (MDR) pathogens, were significantly different between the two hospitals. Central nervous system disorders, dementia and poor performance status, which was possibility related to aspiration pneumonia, were significantly more frequent in patients with NHCAP compared with those with CAP in both hospitals. Atypical pathogens were detected in a few cases in patients with NHCAP., Conclusion: There were many differences in the clinical characteristics between NHCAP patients in a university hospital and a community hospital even for hospitals located in the same area. Aspiration pneumonia was thought to be the main characteristic of NHCAP in both hospitals. Thus, all NHCAP patients did not need the same empiric therapy with a multidrug regimen directed against MDR pathogens. In addition, physicians rarely need to consider atypical pathogens in NHCAP treatment.