Chlamydia Psittaci Research Articles

Applicability of Bronchoalveolar Lavage Fluid and Plasma Metagenomic Next-Generation Sequencing Assays in the Diagnosis of Pneumonia.

Metagenomic next-generation sequencing (mNGS) provides innovative solutions for predicting complex infections. A comprehensive understanding of its strengths and limitations in real-world clinical settings is necessary to ensure that it is not overused or misinterpreted. Two hundred nine cases with suspected pneumonia were recruited to compare the capabilities of 2 available mNGS assays (bronchoalveolar lavage fluid [BALF] mNGS and plasma mNGS) to identify pneumonia-associated DNA/RNA pathogens and predict antibiotic resistance. Compared to clinical diagnosis, BALF mNGS demonstrated a high positive percent agreement (95.3%) but a low negative percent agreement (63.1%). Plasma mNGS revealed a low proportion of true negatives (30%) in predicting pulmonary infection. BALF mNGS independently diagnosed 65.6% (61/93) of coinfections and had a remarkable advantage in detecting caustic, rare, or atypical pathogens. Pathogens susceptible to invasive infection or bloodstream transmission, such as Aspergillus spp, Rhizopus spp, Chlamydia psittaci, and human herpesviruses, are prone to be detected by plasma mNGS. BALF mNGS tests provided a positive impact on the diagnosis and treatment of 128 (61.2%) patients. Plasma mNGS, on the other hand, turned out to be more suitable for diagnosing patients who received mechanical ventilation, developed severe pneumonia, or developed sepsis (all P < .01). BALF mNGS was able to identify resistance genes that matched the phenotypic resistance of 69.4% (25/36) of multidrug-resistant pathogens. Our data reveal new insights into the advantages and disadvantages of 2 different sequencing modalities in pathogen identification and antibiotic resistance prediction for patients with suspected pneumonia.

First detection of herpesvirus and hemosporidians in the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus)

Pathogens affect wild bird populations worldwide, contributing to their decline. Considering the scarce health data regarding the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus), we molecularly surveyed selected pathogens (Newcastle disease virus, Avian influenza virus, Chlamydia psittaci, avian pathogenic Escherichia coli, Campylobacter jejuni, and Salmonella spp.) in 30 Pyrenean Capercaillie feces collected in the field (Catalonia, northeastern Spain). Additionally, swab and tissue samples from eight wild Pyrenean Capercaillies of Catalonia and Andorra were molecularly tested for herpesvirus and hemosporidians (Plasmodium spp., Haemoproteus spp., and Leucocytozoon spp.). All fecal samples were negative for the pathogens tested. Nevertheless, we detected a novel herpesvirus in 50% (4/8) of the Pyrenean Capercaillies, and hemosporidian DNA in 62.5% (5/8) of the tissue samples (i.e., Haemoproteus sp. [4 of 8] and/or Leucocytozoon sp. [3 of 8]). To our knowledge, this is the first detection of herpesvirus and hemosporidians infections in Pyrenean Capercaillies. The putative novel herpesvirus belongs to the genus Iltovirus. The presence of hemosporidian parasites in this mountain bird species is of concern, and could be related to the marked increase in the average temperature in the Pyrenees as a consequence of climate change. Our findings are fundamental to improve the conservation plans for the endangered Pyrenean Capercaillie population.

Clinical utility of metagenomic next-generation sequencing in pathogen detection for lower respiratory tract infections and impact on clinical outcomes in southernmost China.

Today, metagenomic next-generation sequencing (mNGS) has emerged as a diagnostic tool for infections. However, since Hainan has a complicated pathogen spectrum, the diagnostic value and impact on patient outcomes of mNGS in Hainan are to be explored. From April 2020 to October 2021, 266 suspected lower respiratory tract infections (LRTIs) patients in Hainan were enrolled, and specimens were collected before antibiotic treatment. Bronchoalveolar lavage fluid (BALF) samples were subjected to mNGS and culture to compare the diagnostic performance. Other conventional microbiological tests (CMT) were also performed. Patients' treatments and clinical outcomes were recorded, and the antibiotic resistance genes (ARGs) were detected via mNGS workflow. The positive rate of mNGS outperformed that of culture (87.55% vs. 39.30%, p<0.001) and CMT (87.12% vs. 52.65%, p<0.001). Specifically, mNGS detected more P. aeruginosa (12.03% vs 9.02%, p<0.05), H. influenzae (9.77% vs 2.26%, p<0.001), Aspergillus fumigatus (3.00% vs 0.75%, p<0.05), Candida albicans (26.32% vs 7.52%, p<0.001) and uncommon pathogens. It also demonstrated great diagnostic advantages in Mycobacterium tuberculosis with 80% sensitivity and 97.4% specificity. Over half of the patients (147, 55.26%) had modified empirical treatment according to mNGS results and 89.12% of them responded well. For three deaths with modified treatment, multiple drug resistance was predicted by mNGS and confirmed by antibiotic susceptibility test. The application of mNGS can benefit clinics in pathogen identification and antimicrobial treatment stewardship. Physicians should be alert to some emerging uncommon pathogens, including Chlamydia Psittaci, Nocardia otitidiscaviarum, and rare NTM.

Chlamydia psittaci Pneumonia in a patient with motor neuron disease: a case report

BackgroundMotor neuron disease (MND) is a fatal neurodegenerative disorder that leads to progressive loss of motor neurons. Chlamydia psittaci (C. psittaci) is a rare etiology of community-acquired pneumonia characterized primarily by respiratory distress. We reported a case of C. psittaci pneumonia complicated with motor neuron disease (MND).Case presentationA 74-year-old male was referred to the Shaoxing Second Hospital at January, 2022 complaining of fever and fatigue for 2 days. The patient was diagnosed of MND with flail arm syndrome 1 year ago. The metagenomic next-generation sequencing (mNGS) of sputum obtained through bedside fiberoptic bronchoscopy showed C. psittaci infection. Then doxycycline was administrated and bedside fiberoptic bronchoscopy was performed to assist with sputum excretion. Computed Tomography (CT) and fiberoptic bronchoscopy revealed a significant decrease in sputum production. On day 24 after admission, the patient was discharged with slight dyspnea, limited exercise tolerance. One month later after discharge, the patient reported normal respiratory function, and chest CT showed significant absorption of sputum.ConclusionsThe mNGS combined with bedside fiberoptic bronchoscopy could timely detect C. psittaci infection. Bedside fiberoptic bronchoscopy along with antibiotic therapy may be effective for C. psittaci treatment.

Chlamydia psittaci: an emerging cause of equine abortion and fatal neonatal illness in south-eastern Australia.

While well known as a zoonotic pathogen of birds, Chlamydia psittaci is less well recognised as a cause of abortion in mares and severe infection in foals. However, in the past decade it has been causing epizootics of both in south-eastern Australia, as Charles El-Hage and James Gilkerson explain.

Engineering of the LAMP-CRISPR/Cas12b platform for Chlamydia psittaci detection.

Introduction. Chlamydia psittaci (C. psittaci) is a zoonotic infection, that causes psittacosis (parrot fever) in humans, leading to severe clinical manifestations, including severe pneumonia, adult respiratory distress syndrome, and, in rare cases, death.Gap Statement. Rapid, sensitive and specific detection of C. psittaci facilitates timely diagnosis and treatment of patients.Aim. This study aimed to engineer the LAMP-CRISPR/Cas12b platform for C. psittaci detection.Methodology. The loop-mediated isothermal amplification (LAMP) technique and clustered regularly interspaced short palindromic repeats-CRISPR associated protein 12b (CRISPR-Cas12b) assay were combined to establish two-step and one-tube LAMP-CRISPR/Cas12b reaction systems, respectively, for rapidly detecting C. psittaci.Results. The two-step and one-tube LAMP-CRISPR/Cas12b assay could complete detection within 1 h. No cross-reactivity was observed from non-C. psittaci templates with specific LAMP amplification primers and single-guide RNA (sgRNA) targeting the highly conserved short fragment CPSIT_0429 gene of C. psittaci. The detection limits of the two-step and one-tube LAMP-CRISPR/Cas12b reaction were 102 aM and 103 aM, respectively. The results were consistent with qPCR for nucleic acid detection in 160 clinical samples, including 80 suspected C. psittaci samples, kept in the laboratory.Conclusions. The LAMP-CRISPR/Cas12b assay developed in this study provides a sensitive and specific method for rapidly detecting C. psittaci and offers technical support for its rapid diagnosis.

Application of metagenomic next-generation sequencing (mNGS) in diagnosing pneumonia of adults.

Accurate identification of pathogens that cause pulmonary infections is essential for effective treatment and hastening recovery in adults diagnosed with pneumonia. At present, despite metagenomic next-generation sequencing (mNGS) technology has been widely used in clinical practice for pathogen identification, the clinical significance and necessity of detecting pathogen in bronchoalveolar lavage fluid (BALF) for pneumonia-stricken adults remain ambiguous. In this study, 80 patients suffering from pulmonary infection were enrolled, who were admitted to the Affiliated Changzhou Second People's Hospital of Nanjing Medical University between January 2020 and September 2022. The diagnostic performances of mNGS and conventional methods (CM) were systematically analyzed based on BALF samples, and we further investigated the influence of mNGS and CM in diagnosis modification and treatment. We found a significantly higher positive rate for the mNGS method in contrast to CM. Bacteria were the most common pathogens, and Streptococcus pneumoniae was the most commonly identified pathogen. Candida albicans and Epstein-Barr virus were the most frequently identified fungus and virus. Atypical pathogens such as Mycobacterium tuberculosis, virus Nontuberculous mycobacteria, and Chlamydia psittaci were also identified. A total of 77 patients were identified with mixed infections by mNGS. As the disease progressed and recurrent antibiotic treatment persisted, significant dynamic changes in the clinical manifestation from the BALF samples could be found by mNGS. This study underscores the efficacy of mNGS in detecting pathogens in BALF samples from patients suffering pulmonary infections. Compared with the CM, mNGS significantly enhanced the positive diagnosis ratio, particularly in diagnosing Mycobacterium tuberculosis, atypical pathogens, and viral or fungal infections.

Clinical characteristics of a case of severe pneumonia caused by coinfection of COVID-19 and Chlamydia Psittaci

A 69-year-old female patient was admitted to the Department of Respiratory and Critical Care Medicine, Affiliated Hospital of Xuzhou Medical University due to a "cough and fever for eight days". On admission, a coronavirus disease (COVID-19) nucleic acid test was positive, and a chest CT scan showed progressive patchy shadows and consolidation shadows in both lungs. Arterial blood gas analysis showed type Ⅰ respiratory failure. The primary diagnosis was severe community-acquired pneumonia in an older adult without underlying disease. However, oxygen inhalation, steroid, anti-inflammatory, and antibacterial empirical treatment with piperacillin/tazobactam was ineffective. Metagenomic next-generation sequencing of bronchoscopy alveolar lavage fluid showed Chlamydia psittaci(C. psittaci). Severe pneumonia was confirmed, caused by coinfection with severe acute respiratory syndrome coronavirus 2 and C. psittaci. A combination of doxycycline and moxifloxacin significantly improved the targeted and symptomatic treatment of the underlying cause. After discharge, the patient recovered within four weeks of follow-up. Therefore, clinicians should be alert to the possibility of coinfection of C. psittaci in patients already diagnosed with COVID-19.

SNP-based high-resolution typing of Chlamydia psittaci from humans and wild birds in Sweden: circulation of the Mat116 genotype reveals the transmission mode to humans

The incidence of Chlamydia psittaci respiratory tract infections in humans has increased in Sweden in recent years. This study aimed to identify the transmission route by genotyping C. psittaci from infected humans and birds.42 human C. psittaci samples and 5 samples from C. psittaci-infected birds were collected. Genotyping was performed using ompA sequencing, Multi-locus sequence typing, and/or SNP-based high-resolution melting-PCR. Epidemiological data was also collected, and a phylogenetic analysis was conducted.Analysis of ompA provided limited resolution, while the SNP-based PCR analysis successfully detected the Mat116 genotype in 3/5 passerine birds and in 26/29 human cases, indicating a high prevalence of this genotype in the human population. These cases were associated with contact with wild birds, mainly through bird feeding during winter or other outdoor exposure. Human cases caused by other genotypes (psittacine and pigeon) were less common and were linked to exposure to caged birds or pigeons.The SNP-genotype Mat116 is rare, but predominated in this study. The use of SNP-based PCR provided a better understanding of the C. psittaci transmission from birds to humans compared to ompA analysis. In Sweden, human psittacosis appears mainly to be transmitted from garden birds during bird feeding in the winter season.

Forensic investigations of religious rituals involving poultry: a case report

Animal victims of human cruelty are receiving increasing attention from the press and society. Veterinary pathologists and civic authorities have a duty not only to elucidate the cause, method and manner of death but also to address the motivation behind a case. Poultry are commonly used as offering to gods in Santería rituals (ebós). Only a few cases have been reported in scientific journals, in contrast with the number of cases described in the media. Here, a hen and a cockerel (Gallus domesticus) were submitted to the VISAVET Health Surveillance Centre for autopsy, which comprised macroscopic and histological studies and microbiological testing for Chlamydia psittaci, avian orthoavulavirus 1 (Newcastle disease virus), West Nile virus and avian influenza virus. The carcasses were in an active decay stage of decomposition, containing larvae of Lucilia eximia. Both animals had been decapitated and haemorrhages in the cutting region were observed histologically. Post-mortem burns were also observed. To the best of the authors’ knowledge, this is the first post-mortem description of lesions in a domestic avian species due to religious rituals. European Union and Spanish forensic practitioners should be aware that these ritual sacrifices occur in some European countries. Moreover, future European and national legislation updates should consider this type of animal abuse.

Whole genome sequencing characteristics of Chlamydia psittaci caprine AMK-16 strain, a promising killed whole cell veterinary vaccine candidate against chlamydia infection.

Chlamydia psittaci is a primary zoonotic pathogen with a broad host range causing severe respiratory and reproductive system infection in animals and humans. To reduce the global burden of C. psittaci-associated diseases on animal welfare and health and to control the pathogen spread in husbandry, effective vaccines based on promising vaccine candidate(s) are required. Recently, the caprine C. psittaci AMK-16 strain (AMK-16) demonstrated a high level of protection (up to 80-100%) in outbred mice and pregnant rabbits immunized with these formaldehyde-inactivated bacteria against experimental chlamydial wild-type infection. This study investigated the molecular characteristics of AMK-16 by whole-genome sequencing followed by molecular typing, phylogenetic analysis and detection of main immunodominant protein(s) eliciting the immune response in mouse model. Similarly to other C. psittaci, AMK-16 harbored an extrachromosomal plasmid. The whole-genome phylogenetic analysis proved that AMK-16 strain belonging to ST28 clustered with only C. psittaci but not with Chlamydia abortus strains. However, AMK-16 possessed the insert which resulted from the recombination event as the additional single chromosome region of a 23,100 bp size with higher homology to C. abortus (98.38-99.94%) rather than to C. psittaci (92.06-92.55%). At least six of 16 CDSs were absent in AMK-16 plasticity zone and 41 CDSs in other loci compared with the reference C. psittaci 6BC strain. Two SNPs identified in the AMK-16 ompA sequence resulted in MOMP polymorphism followed by the formation of a novel genotype/subtype including three other C. psittaci strains else. AMK-16 MOMP provided marked specific cellular and humoral immune response in 100% of mice immunized with the inactivated AMK-16 bacteria. Both DnaK and GrpE encoded by the recombination region genes were less immunoreactive, inducing only a negligible T-cell murine immune response, while homologous antibodies could be detected in 50% and 30% of immunized mice, respectively. Thus, AMK-16 could be a promising vaccine candidate for the development of a killed whole cell vaccine against chlamydiosis in livestock.

MiR-184 targeting FOXO1 regulates host-cell oxidative stress induced by Chlamydia psittaci via the Wnt/β-catenin signaling pathway.

Chlamydia psittaci is a human pathogen that causes atypical pneumonia after zoonotic transmission. We confirmed that C. psittaci infection induces oxidative stress in human bronchial epithelial (HBEs) cells and explored how this is regulated through miR-184 and the Wnt/β-catenin signaling pathway. miR-184 mimic, miR-184 inhibitor, FOXO1 siRNA, or negative control sequence was transfected into HBE cells cultured in serum-free medium using Lipofectamine 2000. Then, prior to the cells were infected with C. psittaci 6BC, and the cells were treated with or without 30 µM Wnt/β-catenin inhibitor ICG-001. Quantification of reactive oxygen species, malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione was carried out according to the manufacturer's protocol using a corresponding assay kit. The outcome of both protein and gene was measured by western blotting or real-time fluorescence quantitative PCR. In C. psittaci-infected HBE cells, miR-184 was upregulated, while one of its target genes, FOXO1, was downregulated. ROS and MDA levels increased, while SOD and GSH contents decreased after C. psittaci infection. When miR-184 expression was downregulated, the level of oxidative stress caused by C. psittaci infection was reduced, and the Wnt/β-catenin signaling pathway was inhibited. The opposite results were seen when miR-184 mimic was used. Transfecting with FOXO1 siRNA reversed the effect of miR-184 inhibitor. Moreover, when the Wnt/β-catenin-specific inhibitor ICG-001 was used, the level of oxidative stress induced by C. psittaci infection was significantly suppressed. miR-184 can target FOXO1 to promote oxidative stress in HBE cells following C. psittaci infection by activation of the Wnt/β-catenin signaling pathway.

Computational exploration and design of a multi-epitopes vaccine construct against Chlamydia psittaci

Chlamydia psittaci is an intracellular pathogen and causes variety of deadly infections in humans. Antibiotics are effective against C. psittaci however high percentage of resistant strains have been reported in recent times. As there is no licensed vaccine, we used in-silico techniques to design a multi-epitopes vaccine against C. psittaci. Following a step-wise protocol, the proteome of available 26 strains was retrieved and filtered for subcellular localized proteins. Five proteins were selected (2 extracellular and 3 outer membrane) and were further analyzed for B-cell and T-cell epitopes prediction. Epitopes were further checked for antigenicity, solubility, stability, toxigenicity, allergenicity, and adhesive properties. Filtered epitopes were linked via linkers and the 3D structure of the designed vaccine construct was predicted. Binding of the designed vaccine with immune receptors: MHC-I, MHC-II, and TLR-4 was analyzed, which resulted in docking energy scores of −4.37 kcal/mol, −0.20 kcal/mol and −22.38 kcal/mol, respectively. Further, the docked complexes showed stable dynamics with a maximum value of vaccine-MHC-I complex (7.8 Å), vaccine-MHC-II complex (6.2 Å) and vaccine-TLR4 complex (5.2 Å). As per the results, the designed vaccine construct reported robust immune responses to protect the host against C. psittaci infections. In the study, the C. psittaci proteomes were considered in pan-genome analysis to extract core proteins. The pan-genome analysis was conducted using bacterial pan-genome analysis (BPGA) software. The core proteins were checked further for non-redundant proteins using a CD-Hit server. Surface localized proteins were investigated using PSORTb v 3.0. The surface proteins were BLASTp against Virulence Factor Data Base (VFDB) to predict virulent factors. Antigenicity prediction of the shortlisted proteins was further done using VAXIGEN v 2.0. The epitope mapping was done using the immune epitope database (IEDB). A multi-epitopes vaccine was built and a 3D structure was generated using 3Dprot online server. The docking analysis of the designed vaccine with immune receptors was carried out using PATCHDOCK. Molecular dynamics and post-simulation analyses were carried out using AMBER v20 to decipher the dynamics stability and intermolecular binding energies of the docked complexes. Communicated by Ramaswamy H. Sarma

Clinical analysis of severe Chlamydia psittaci pneumonia: Case series study.

The clinical characteristics and diagnosis of ten cases with severe Chlamydia psittaci pneumonia were analyzed. Ten patients had high fever, cough, or diarrhea, and all had a history of contact with birds or poultry. The white blood cell count of the patients was normal or slightly increased. The percentage of neutrophils (N%) and C reactive protein of the patients were significantly increased. Chest computer tomography showed patchy consolidation of both lungs, with one-sided lung lobes prominent, and bronchial inflation signs. All the patients were admitted to the intensive care unit due to respiratory failure. Nine patients needed ventilator-assisted ventilation therapy, and one patient needed high-flow oxygen therapy. All patients had sepsis, and five patients developed septic shock. The patients were diagnosed with severe C. psittaci pneumonia by clinical manifestations and contact history. After timely adjustment of tetracycline-based treatment, eight patients recovered and were discharged, and two patients died of septic shock and respiratory failure. Patients with poultry contact should be cautious toward C. psittaci pneumonia. A better method for the detection of C. psittaci is metagenomic next-generation sequencing. Its examination can shorten the diagnosis time. In a later stage, large-sample research is needed to guide clinical diagnosis and treatment.

Psittacosis: An Underappreciated and Often Undiagnosed Disease.

The bacterial agent Chlamydia psittaci, and the resulting disease of psittacosis, is a little-known and underappreciated infectious disease by healthcare practitioners and in public health in general. C. psittaci infections can cause significant psittacosis outbreaks, with person-to-person transmission documented in the last decade. In this publication, we review the pathogen and its disease, as well as examine the potential for genetic manipulation in this organism to create a more deadly pathogen. Recent disease surveys indicate that currently, the highest incidences of human disease exist in Australia, Germany and the UK. We recommend the universal public health reporting of C. psittaci and psittacosis disease and increasing the promotion of public health awareness.

Значение РСК и ПЦР в диагностике экспериментальной инфекции кроликов, вызванной Chlamydia psittaci

Specific antibodies against сhlamydia were detected using complement fixation test and сhlamydia genome was detected using polymerase chain reaction in pregnant rabbits experimentally infected with Chlamydia psittaci. The infected rabbits developed a fever and respiratory signs and the infection was confirmed by specific antibodies against сhlamydia detected in their blood and by abnormalities in rabbit kindling. Complement fixation test of paired rabbit sera revealed an increase in the titers of specific antibodies against сhlamydia, which on Day 7 post infection varied within 1:7.5; on Day 14, mean concentration was 1:40 and by Day 30 mean titer increased to 1:60. However, when pathological materials from the urogenital tract of the experimental animals were tested in polymerase chain reaction and in smear microscopy, it was impossible to confirm that there is an etiological link between сhlamydia and kindling problems in experimental animals. At the same time, molecular and genetic tests of internal organs (liver) sampled from stillborn baby rabbits revealed the сhlamydia genome, thus, proving сhlamydia involvement into the pathological kindling. Therefore, such a retrospective method as complement fixation test with a сhlamydia antigen is of high diagnostic value for lifetime сhlamydia diagnosis.

Application Value of Next-Generation Sequencing of Bronchial Alveolar Lavage Fluid in Emergency Patients with Infection.

This study was performed to explore the application value of next-generation sequencing (NGS) of bronchial alveolar lavage fluid (BALF) in emergency patients with infection. In this regard, a total of 52 patients with infection who were diagnosed and treated in the emergency department of our hospital from September 2019 to September 2021 were selected as the research objects. The BALF of the patients was analyzed by NGS, and the results were compared with the pathogen detection results of traditional microbial culture of the patients to analyze the diagnostic value of NGS in patients with infection. The results showed that among the 52 patients, 47 were positive by NGS and 13 were positive by traditional microbial culture. The pathogen detection rate of NGS was higher than that of traditional microbial culture[90.4% (47/52) VS 25% (13/52), χ2=45.539, P<0.001], and was able to detect viruses, fungi and other special pathogens that were difficult to be detected by traditional microbial culture, such as Chlamydia psittaci. A total of 129 pathogens were detected in the NGS test results of 47 of these patients, including bacteria, fungi, viruses and mycoplasma/chlamydia. 14 pathogens were detected in the conventional microbiological cultures of 13 patients, including bacteria and fungi. Overall, compared with traditional microbial culture methods, NGS detection has higher accuracy and can effectively detect pathogens that cannot be detected by traditional microbial culture. It has a high application value in the diagnosis of pathogens and can provide clinical guidance for the diagnosis of pathogens in patients with emergency infections.

A pediatric case of Chlamydia psittaci caused severe Acute Respiratory Distress Syndrome (ARDS) in Italy

BackgroundThis case of psittacosis in children, is the first described in literature, in Italy. This respiratory infection can be transmitted to humans from the inhalation of respiratory secretions, feces and plumage aerosol of infected birds (and other animals). Usually it can have an asymptomatic or paucisymptomatic course, and the onset is often flu-like, but in this case the child risked his life for a severe respiratory failure. This report is unique because in children psittacosis is rare, and always misdiagnosed, or could cause a delayed diagnosis because of lack of awareness among the paediatricians and physicians. Furthermore, psittacosis enters a differential diagnosis with SARS-COV2 infection because both diseases may determine dyspnea and atypical pneumonia, up to acute respiratory failure.Case presentationThis clinical case talks about a three-and-a-half-year-old male child affected by psittacosis (or ornithosis), with severe dyspnea and systemic symptoms who required oro-tracheal intubation for acute respiratory failure. The child had slept in a room at home, with some recently bought parrots affected by psittacosis. Initially the child was treated with empiric antibiotic therapy (i.v.ceftriaxone and teicoplanin), but after having isolated the DNA of the germ “Chlamydia psittaci” in both serological and through bronchoalveolar lavage (BAL), he was treated with targeted antibiotic therapy: tetracyclines (doxicillin).ConclusionsPsittacosis is an extremely contagious disease, caused by an intracellular germ, called “Chlamydia psittaci”, a Gram-negative bacterium, transmitted to humans in particular by infected birds, responsible for atypical pneumonia, with acute and chronic respiratory symptoms, sometimes with multi-organ failure and disseminated intravascular coagulation. Even if it is a rare respiratory disease among children, a good doctor must think about psittacosis as cause of respiratory symptoms (and not only flu or SARS-COV2), above all through a correct medical history, in order to provide a targeted antibiotic therapy. An interesting case of psittacosis in a child is being reported here, which has been treated successfully with doxycillin.

TLR2 mediates autophagy through ERK signaling pathway in Chlamydia psittaci CPSIT_p7 protein-stimulated RAW264.7 cells.

Chlamydia psittaci is a zoonotic pathogen found in birds and humans. Macrophages, major components of the innate immune system, can resist chlamydial infections and trigger adaptive immune responses. However, the molecular mechanisms underlying the action of macrophages against C. psittaci infection are not well understood. This study investigated the roles and mechanisms of plasmid-encoded protein CPSIT_p7 of C. psittaci in regulating autophagy in RAW264.7 cells. The results demonstrated that stimulation of RAW264.7 with C. psittaci plasmid protein CPSIT_p7 induced the expressions of the autophagy signaling primary regulators LC3 and Beclin1, which could also significantly induce the phosphorylation levels of ERK, JNK, p38, and Akt. Next, siRNA knockdown of TLR2 resulted in significant downregulation of CPSIT_p7-triggered autophagy in RAW264.7 cells. Moreover, the extracellular regulated protein kinase (ERK) inhibitor PD98059 markedly reduced autophagy in CPSIT_p7-stimulated macrophages. In summary, these results indicated that TLR2 plays an essential role in the induction of autophagy through the ERK signaling pathway in CPSIT_p7-stimulated RAW264.7 cells.

Chlamydia psittaci pneumonia in Wuxi, China: retrospective analysis of 55 cases and predictors of severe disease.

More and more patients with community-acquired pneumonia have been detected with Chlamydia psittaci (C. psittaci) infected using metagenomic next-generation sequencing (mNGS). Previously, this was unheard of, and several patients presented with severe pneumonia and even required ECMO. We aimed to clarify the clinical characteristics of C. psittaci pneumonia and find out if there are any possible predictors of severe C. psittaci pneumonia. In this retrospective study, we included all confirmed cases of C. psittaci pneumonia in Wuxi. Epidemiological, clinical, and radiological features, as well as laboratory data, were collected and analyzed. We enrolled 55 patients with C. psittaci pneumonia, with 30 (54.5%) having a history of exposure to birds or their internal organs. 50 (90.9%) patients were diagnosed by mNGS. Patients with C. psittaci pneumonia had many complications, among which, that deserve sufficient attention from clinicians were vascular embolic events (3, 5.5%). High fever was the most common clinical manifestation (41, 74.5%). The majority of patients had a significant increase in neutrophils ratio, neutrophils to lymphocytes ratio (NLR), rapid c-reactive protein, creatine kinase (CK), and lactate dehydrogenase (LDH), as well as a decrease in lymphocytes ratio, albumin, serum sodium, serum potassium, and serum phosphorus. Chest computed tomography scans revealed unilateral pneumonia (70.9%), consolidation (87.3%), air bronchogram (76.4%), and ground-glass opacity (69.1%). The neutrophil ratio, NLR, LDH, and CK were all factors that could identify severe pneumonia. Both AUCs exceeded 0.8; the respective 95% CIs were 0.715-0.944, 0.710-0.963, 0.677-0.937, and 0.718-0.950; all p < 0.05 (0.01, 0.001, 0.007, 0.007 respectively). The ORs were 10.057, 9.750, 10.057, and 9.667, respectively; the 95% CIs were 2.643-38.276, 2.339-40.649, and 2.643-38.276, respectively; all p-values were less than 0.05 (0.001, 0.002, 0.001, 0.001 respectively). C. psittaci pneumonia is a very complex disease that changes all the time. Some patients showed severe pneumonia. Patients will have a poor prognosis if they are not treated promptly and effectively. We discovered that many clinical indicators were typical. Meanwhile, significant increases in neutrophil ratio, NLR, LDH, and CK predicted severe pneumonia. Timely detection of mNGS provided substantial help for clinical diagnosis and early treatment.