Human-to-human transmission of Chlamydia psittaci in China, 2020: an epidemiological and aetiological investigation

Chlamydia psittaci detected at a live poultry wholesale market in central China

BACKGROUND

We investigated the presence of Chlamydia psittaci in poultry and the environment in live poultry wholesale markets in Changsha during 2021-2022 and conducted a phylogenetic analysis to understand its distribution in this market.

METHODS

In total, 483 samples were analyzed using real-time polymerase chain reaction and 17 C. psittaci-positive samples using high-throughput sequencing, BLAST similarity, and phylogenetic analysis.

RESULTS

Twenty-two out of 483 poultry and environmental samples were positive for C. psittaci (overall positivity rate: 4.55%) with no difference in positivity rates over 12 months. Chlamydia psittaci was detected at 11 sampling points (overall positivity rate: 27.5%), including chicken, duck, and pigeon/chicken/duck/goose shops, with pigeon shops having the highest positivity rate (46.67%). The highest positivity rates were found in sewage (12.5%), poultry fecal (7.43%), cage swab (6.59%), avian pharyngeal/cloacal swab (3.33%), and air (2.29%) samples. The ompA sequences were identified in two strains of C. psittaci, which were determined to bear genotype B using phylogenetic analysis. Thus, during monitoring, C. psittaci genotype B was detected in the poultry and environmental samples from the poultry wholesale market in Changsha.

CONCLUSIONS

To address the potential zoonotic threat, C. psittaci monitoring programs in live poultry markets should be enhanced.

Diagnosis of a Familial Psittacosis Outbreak with Clinical Analysis and Metagenomic Next-Generation Sequencing Under COVID-19: A Case Series

Purpose

To explore the clinical characteristics, diagnosis, and treatment of family outbreak of psittacosis and to improve the success rate of treatment.

Patients and Methods

The clinical characteristics, diagnosis, treatment, and outcome of family outbreak of psittacosis, which consists three patients, diagnosed by clinical analysis and metagenomic next-generation sequencing (mNGS) in our hospital were analyzed retrospectively.

Results

We report on three instances of clustered atypical pneumonia, which were caused by Chlamydia psittaci during the COVID-19 pandemic. All patients exhibited symptoms of fever and cough, while one patient also experienced gastrointestinal symptoms such as nausea, vomiting, and diarrhea. Laboratory tests indicated no significant increase in leukocytes and neutrophils, but a mild increase in C-reactive protein was observed in all three patients. Chest computed tomography (CT) scans revealed a consolidation shadow in a unilateral lung lobe in all three patients. Both patients were treated with empirical moxifloxacin, yielding unsatisfactory outcomes. mNGS was conducted on sputum samples from one adult patient, revealing the presence of Chlamydia psittaci. Additional doxycycline was prescribed immediately, and then the patients' temperatures were stabilized, and the lesion in chest CT was absorbed. The pediatric patient exhibited less severe symptoms compared to the adult patients and exhibited a favorable response to azithromycin administration.

Conclusion

This study reports a cluster of a family outbreak of atypical pneumonia caused by C. psittaci in China. The occurrence of a family outbreak during the COVID-19 pandemic may be attributed to familial aggregation resulting from the epidemic. The three cases reported in this study did not experience severe complications, which can be attributed to the prompt medical intervention and swift diagnosis. This finding implies the need to enhance patients' awareness and vigilance towards their health. Additionally, mNGS emerges as a valuable technique for accurately identifying pathogens causing pulmonary infections.

Evaluation of clinical characteristics and risk factors associated with Chlamydia psittaci infection based on metagenomic next-generation sequencing

INTRODUCTION

Psittacosis is a zoonosis caused by Chlamydia psittaci, the clinical manifestations of Psittacosis range from mild illness to fulminant severe pneumonia with multiple organ failure. This study aimed to evaluate the clinical characteristics of Chlamydia psittaci infection diagnosed based on metagenomic next-generation sequencing(mNGS), as well as the risk factors affecting the progress of Chlamydia psittaci infection, in order to improve the effect of therapeutics.

METHODS

We retrospectively analyzed the clinical data of patients infected with chlamydia psittaci in the First Affiliated Hospital of Nanchang University from January 2021 to December 2021. The patient's past medical history, clinical manifestations, laboratory examinations, chest CT results, treatment status, and prognosis data were collected. we also investigated both the pathogenic profile characteristics and the lower respiratory tract microbiota of patients with Chlamydia psittaci pneumonia using mNGS.

RESULTS

All cases of Chlamydia psittaci in our research have been confirmed by mNGS. Among 46 cases of Chlamydia psittaci pneumonia, Poultry exposure was reported in 35 cases. In severe cases of Chlamydia psittaci pneumonia, Neutrophils, Procalcitonin (PCT), Lactate Dehydrogenase (LDH), Hydroxybutyrate Dehydrogenase (HBDH), Creatine Kinase Isoenzymes-B (CK-MB) and D-Dimer levels were remarkably higher than that of non-severe cases, except for lymphocytes (all P < 0.05). Chest CT scans showed Bilateral (77.8%), multiple lobar lungs (85.2%), pleural effusions (44.4%) involvement in those suffering from severe Chlamydia psittaci pneumonia, whereas its incidence was 0%, 21.1% and 10.5% in non-severe patients, respectively (P < 0.05). Multivariate analysis revealed that higher lymphocyte concentrations (OR 0.836, 95% CI 0.714-0.962, P = 0.041) were the only protective factor for survival. mNGS results indicated that 41.3% of patients (19/46) had suspected coinfections with a coinfection rate of 84.2% (16/19) in the severe group, much higher than that in the non severe group (p < 0.05). No significantly different profiles of lower respiratory tract microbiota diversity were found between non severe group and severe group.

CONCLUSION

A history of poultry exposure in patients can serve as an important basis for diagnosing Chlamydia psittaci pneumonia, and patients with severe Chlamydia psittaci pneumonia are more likely to develop elevated inflammatory biomarkers as well as elevated cardiac markers. Higher lymphocyte concentrations are protective factors associated with severe C. psittaci pneumonia. The higher proportion of patients with coinfections in our study supports the use of mNGS for comprehensive early detection of respiratory infections in patients with C. psittaci pneumonia.

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.

Clinical Characteristics of Chlamydia psittaci Infection Diagnosed by Metagenomic Next-Generation Sequencing: A Retrospective Multi-Center Study in Fujian, China

Objective

This study aimed to describe and compare the epidemiological, demographic, clinical, laboratory and radiological characteristics as well as the complications, treatments, and outcomes of these patients.

Methods

We retrospectively investigated clinical data of patients with C. psittaci infection (psittacosis) in eight Grade IIIA hospitals of Fujian. Metagenomic next-generation sequencing (mNGS) was used identify C. psittaci in clinical samples of all included patients.

Results

A total of 74 patients (39 severe/35 non-severe) was diagnosed with psittacosis, 25 (33.8%) of whom had history of poultry exposure. Common symptoms included high fever (98% [37/74]), fatigue (52.7% [39/74]), and dyspnea (51.4% [38/74]). Common manifestations in imaging included consolidation (89.2%), pleural effusion (77.0%), and air bronchogram (66.2%). Common complications included acute respiratory distress syndrome (55.4% [41/74]), type I respiratory failure (52.7% [39/74]), acute liver injury (41.9% [31/74]), and secondary infection (27.0% [20/74]). The in-hospital mortality rate was 8.11% (6/74).

Conclusion

C. psittaci infection is represents an underestimated cause of CAP. For SCAP patients with poultry and bird contact history, specimens were encouraged to be sended for mNGS test in time. C. psittaci infection can lead to severe, multiple system involvement, and several complications. mNGS facilitate timely diagnosis of C. psittaci infection.

Clinical features and risk factors of liver injury in patients with Chlamydia psittaci pneumonia- a retrospective analysis

Background

Research into the effects of Chlamydia psittaci pneumonia on the liver has emerged in the last few years. However, no studies have systematically described liver injury in patients with psittacosis. We present the first report on the clinical features and risk factors of liver injury in patients with Chlamydia psittaci pneumonia.

Methods

We retrospectively collected the clinical parameters for 46 patients with Chlamydia psittaci pneumonia admitted to Jinhua Central Hospital from January 2019 to February 2023. We analyzed the liver function parameters and summarized the clinical characteristics and risk factors of liver injury.

Results

Among the 46 patients, 39 (84.8%) had abnormal liver function, and 23 (50.0%) had liver injury. The ratio of patients with a history of alcohol consumption (39.1% vs. 4.3%, P =0.004) or severe pneumonia (56.5% vs. 26.1%, P =0.036) was higher in the liver injury group compared with the non-liver injury group. Laboratory tests showed higher lactate dehydrogenase (LDH) levels in the liver injury group (P <0.001). The optimal cut-off LDH level associated with liver injury was 473 IU/L as determined by ROC curve analysis. Furthermore, multivariate logistic regression analysis demonstrated that a history of alcohol consumption (odds ratio [OR] = 11.251; 95% confidence interval [CI] = 1.022 ~ 123.897, P =0.048) and an LDH level of ≥ 473IU/L (OR = 11.635, 95% CI = 1.832 ~ 73.869, P =0.009) were independent risk factors for liver injury.

Conclusions

A history of alcohol consumption and an LDH level of over 473 IU/L are independent risk factors for Chlamydia psittaci pneumonia-related liver injury. It is recommended that particular attention be given to monitoring and evaluating liver function parameters when treating patients with Chlamydia psittaci pneumonia who have a high LDH level and history of alcohol consumption.

Venous-arterial extracorporeal membrane oxygenation for psittacosis pneumonia complicated with cardiogenic shock: case report and literature review

INTRODUCTION

Dilated cardiomyopathy (DCM) is characterized by the enlargement of the left ventricle or biventricular, accompanied by myocardial systolic dysfunction. Chlamydia psittacosis (CP) is a zoonotic pathogen, which can cause severe pneumonia, respiratory failure, and acute organ dysfunction. The deterioration of DCM caused by CP infection is extremely rare, and few cases of successful management were reported.

CASE PRESENTATION

We reported a 67-year-old male patient with DCM and chronic heart failure. Who was admitted to ICU with severe pneumonia, acute hypoxemic respiratory failure, acute decompensated heart failure, arrhythmia, and cardiogenic shock. Mechanical ventilation (MV) and venous-arterial extracorporeal membrane oxygenation (VA-ECMO) were established for respiratory and circulatory support. Broncho alveolar lavage fluid(BALF)was collected for culture and metagenomics next-generation sequencing (mNGS) test. Repeated mNGS tests indicated the high possibility of CP pneumonia, thereafter, moxifloxacin and doxycycline were prescribed. After targeted antibiotics and organ support treatment, pneumonia, respiratory and circulatory failure were gradually resolved, patient was successfully weaned from MV and VA-ECMO. Finally, the patient was recovered and discharged alive.

CONCLUSIONS

Severe respiratory and circulatory failure caused by CP infection in DCM patients is a rare life-threatening clinical condition. Early accurate diagnosis, targeted antibiotic therapy, coupled with extracorporeal life support posed positive impact on the patient's disease course and outcome.

Changes in the airway microbiome in patients with bronchiectasis

This study used metagenomic next-generation sequencing (mNGS) technology to explore the changes of the microbial characteristics in the lower respiratory tract in patients with acute exacerbations of bronchiectasis (noncystic fibrosis) to guide clinical treatment and improve patients' quality of life and prognosis. This prospective study included 54 patients with acute exacerbation and 46 clinically stable patients admitted to the Respiratory and Critical Care Medicine Center of the People's Hospital of Xinjiang Uygur Autonomous Region from January 2020 to July 2022. Sputum was subjected to routine microbiological tests, and bronchoalveolar lavage fluid (BALF) samples were subjected to microbiological tests and mNGS of BALF before empirical antibiotic therapy. Serum inflammatory markers (white blood cell count, interleukin-6, procalcitonin, and C-reactive protein) were measured. In addition, we evaluated the pathogen of mNGS and compared the airway microbiome composition of patients with acute exacerbation and control patients. The mean age of our cohort was 56 ± 15.2 years. Eighty-nine patients had positive results by mNGS. There was a significant difference in the detection of viruses between the groups (χ2 = 6.954, P < .01). The fungal species Candida albicans, Pneumocystis jirovecii, and Aspergillus fumigatus were significantly more common in patients with acute exacerbations (χ2 = 5.98, P = .014). The bacterial species Acinetobacter baumannii, Mycobacterium tuberculosis, Haemophilus influenzae, Haemophilus parahaemolyticus, Abiotrophia defectiva, and Micromonas micros were significantly more prevalent in patients with acute exacerbations (χ2 = 4.065, P = .044). The most common bacterial species isolated from the sputum and BALF samples of patients with acute exacerbation was A. baumannii. Chlamydia psittaci was found in 4 patients. In addition, of 77 patients with negative sputum culture, 66 had positive results by mNGS, demonstrating the increased sensitivity and accuracy of mNGS. Patients with acute exacerbation of bronchiectasis tend to have mixed infections in the lower respiratory tract. The frequency of viruses, fungi, and Mycoplasma was higher in these patients. Our findings suggest that mNGS could be used to identify pathogenic microorganisms in these patients, increasing the effectiveness of antibiotic therapy.

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

BACKGROUND

Motor 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 PRESENTATION

A 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.

CONCLUSIONS

The 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.

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.

Chlamydia psittaci Pneumonia-Induced Pulmonary Thrombosis: A Case Report

Chlamydia psittaci pneumonia frequently leads to various extrapulmonary complications; however, reports of C. psittaci-pneumonia complicated by pulmonary thrombosis are uncommon. We report a case of severe C. psittaci pneumonia in a patient with a history of poultry contact and clinical manifestations including hyperpyrexia, dyspnea, and respiratory failure, which necessitated tracheal intubation for assisted ventilation. C. psittaci in bronchoalveolar lavage fluid was detected with metagenomic next-generation sequencing. Following targeted antibiotic therapy, the fever subsided, although dyspnea persisted without significant improvement, and chest pain developed. Compared to previous measurements, the D-dimer level increased, and CT pulmonary angiography revealed thromboses in the pulmonary artery trunk and left pulmonary artery. The symptoms improved after anticoagulant treatment, and the patient was discharged subsequently. This study suggests that C. psittaci infection may be associated with the formation of pulmonary thrombosis. Additional clinical data are required to support this inference. Following targeted antibiotic therapy, if persistent dyspnea, chest pain, and increased D-dimer level are present, pulmonary thrombosis should be considered, and pulmonary artery angiography can confirm the diagnosis.

Acute abdominal pain as the first symptom of Chlamydia psittaci pneumonia complicated by acute pancreatitis: a case report

Background

Chlamydia psittaci infections primarily cause damage to the lungs but may also affect the cardiovascular system, gastrointestinal tract, liver, kidney, and brain, resulting in a variety of extrapulmonary complications. However, reports regarding C. psittaci infection-associated pancreatitis are rare. In this report, a patient with C. psittaci pneumonia complicated by acute pancreatitis is presented.

Case description

The patient presented with acute upper abdominal pain and developed severe pyrexia and dyspnoea one day later. A chest computed tomography image revealed patchy consolidation in the left lung. The disease progressed rapidly, and the patient exhibited liver and kidney damage and type 1 respiratory failure within a short period of time. Metagenomic next-generation sequencing of alveolar lavage fluid revealed the presence of C. psittaci. The patient was administered doxycycline and moxifloxacin, after which the patient's abdominal pain and lung infection significantly resolved.

Conclusion

This case report demonstrates that extrapulmonary C. psittaci infections due to secondary acute pancreatitis can manifest as abdominal pain, although the exact mechanisms of C. psittaci caused by acute pancreatitis remain unclear. Timely diagnoses and treatments of such infections are necessary to achieve favorable clinical outcomes.

Case Report: Metagenomic next-generation sequencing applied in diagnosing psittacosis caused by Chlamydia psittaci infection

Background

Chlamydia psittaci is the causative agent of psittacosis in humans, while its rapid identification is hampered due to the lack of specificity of laboratory testing methods.

Case presentation

This study reports four cases of C. psittaci infection after contact with a domestic parrot, all belonging to the same family. Common manifestations like fever, cough, headache, nausea, and hypodynamia appeared in the patients. Metagenomic next-generation sequencing (mNGS) aided the etiological diagnosis of psittacosis, revealing 58318 and 7 sequence reads corresponding to C. psittaci in two cases. The detected C. psittaci was typed as ST100001 in the Multilocus-sequence typing (MLST) system, a novel strain initially reported. Based on the results of pathogenic identification by mNGS, the four patients were individually, treated with different antibiotics, and discharged with favorable outcomes.

Conclusion

In diagnosing psittacosis caused by a rare C. psittaci agent, mNGS provides rapid etiological identification, contributing to targeted antibiotic therapy and favorable outcomes. This study also reminds clinicians to raise awareness of psittacosis when encountering family members with a fever of unknown origin.

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.

Case Report: Clinical analysis of a cluster outbreak of chlamydia psittaci pneumonia

Objective

To explore the clinical characteristics and prognosis of clustered cases of psittacosis pneumonia.

Method

We retrospectively analyzed the clinical data of a cluster outbreak of psittacosis pneumonia. The analysis included epidemiological data, clinical symptoms, laboratory results, and prognosis. The diagnosis was made using mNGS and nested PCR technology.

Result

Of the four cases, two had direct contact with diseased poultry while the other two did not. All cases presented with more than 39.5 °C fever and chills. Additionally, significant increases in C-reactive protein, ferritin, creatine kinase, and lactate dehydrogenase were observed in all cases, while absolute lymphocyte count decreased. Case 2 also had increased calcitonin levels. Acute respiratory failure occurred during the treatment of case 1 and case 2, leading to tracheal intubation and ventilator-assisted ventilation. Unfortunately, case 2 passed away due to sepsis and multiple organ dysfunction, while the other cases had a positive prognosis.

Conclusion

mNGS facilitated the early diagnosis of psittacosis pneumonia. It is important to note that there is still a substantial risk of human-to-human transmission in psittacosis pneumonia. Absolute lymphocyte count and calcitonin levels can predict the severity and prognosis of the disease.

Epidemiological and clinical characteristics of a family cluster of psittacosis: A case report

Psittacosis accounts for 1-2 % of community-acquired pneumonia. In recent years, reports of psittacosis are increasing. Most reported cases of psittacosis are sporadic. Here, we report a familial cluster of five patients infected with Chlamydophila in a northwest Chinese region and share our diagnosis and treatment experience. The epidemiological characteristics, clinical features, laboratory examinations of family cluster psittacosis were collected and analyzed. We closely followed up all the family members and analyzed their clinical outcome. Five cases of family clustered pneumonia were mainly characterized by fever, cough and fatigue. mNGS rapidly identified the infecting agent as Chlamydophila in case 1 followed by RT-PCR analysis. A newly purchased pet parrot, which had diarrhea, was probably the primary source of infection. The main change of inflammation index in five patients was the decrease of lymphocyte counts. Chest CT showed peripheral or subpleural involvement of patchy high-density shadows with bronchial ventilation signs and blurred edges, mostly unilateral lesions. Five cases were completely cured with moxifloxacin and azithromycin. Our findings suggest that a familial cluster of Chlamydophila infection maybe caused by contact with sick pet parrot or human to human transmission in one close family. For this community-acquired pneumonia, epidemiological characteristics and use of mNGS is very important for improving accuracy in the early diagnosis.

Whole-genome sequencing of Chlamydia psittaci from Australasian avian hosts: A genomics approach to a pathogen that still ruffles feathers

Chlamydia psittaci is a globally distributed veterinary pathogen with zoonotic potential. Although C. psittaci infections have been reported in various hosts, isolation and culture of Chlamydia is challenging, hampering efforts to produce contemporary global C. psittaci genomes. This is particularly evident in the lack of avian C. psittaci genomes from Australia and New Zealand. In this study, we used culture-independent probe-based whole-genome sequencing to expand the global C. psittaci genome catalogue. Here, we provide new C. psittaci genomes from two pigeons, six psittacines, and novel hosts such as the Australian bustard (Ardeotis australis) and sooty shearwater (Ardenna grisea) from Australia and New Zealand. We also evaluated C. psittaci genetic diversity using multilocus sequence typing (MLST) and major outer membrane protein (ompA) genotyping on additional C. psittaci-positive samples from various captive avian hosts and field isolates from Australasia. We showed that the first C. psittaci genomes sequenced from New Zealand parrots and pigeons belong to the clonal sequence type (ST)24 and diverse 'pigeon-type' ST27 clade, respectively. Australian parrot-derived strains also clustered in the ST24 group, whereas the novel ST332 strain from the Australian bustard clustered in a genetically diverse clade of strains from a fulmar, parrot, and livestock. MLST and ompA genotyping revealed ST24/ompA genotype A in wild and captive parrots and a sooty shearwater, whilst 'pigeon-types' (ST27/35 and ompA genotypes B/E) were found in pigeons and other atypical hosts, such as captive parrots, a little blue penguin/Kororā (Eudyptula minor) and a zebra finch (Taeniopygia guttata castanotis) from Australia and New Zealand. This study provides new insights into the global phylogenomic diversity of C. psittaci and further demonstrates the multi-host generalist capacity of this pathogen.

Clinical identification and microbiota analysis of Chlamydia psittaci- and Chlamydia abortus- pneumonia by metagenomic next-generation sequencing

Introduction

Recently, the incidence of chlamydial pneumonia caused by rare pathogens such as C. psittaci or C. abortus has shown a significant upward trend. The non-specific clinical manifestations and the limitations of traditional pathogen identification methods determine that chlamydial pneumonia is likely to be poorly diagnosed or even misdiagnosed, and may further result in delayed treatment or unnecessary antibiotic use. mNGS's non-preference and high sensitivity give us the opportunity to obtain more sensitive detection results than traditional methods for rare pathogens such as C. psittaci or C. abortus.

Methods

In the present study, we investigated both the pathogenic profile characteristics and the lower respiratory tract microbiota of pneumonia patients with different chlamydial infection patterns using mNGS.

Results

More co-infecting pathogens were found to be detectable in clinical samples from patients infected with C. psittaci compared to C. abortus, suggesting that patients infected with C. psittaci may have a higher risk of mixed infection, which in turn leads to more severe clinical symptoms and a longer disease course cycle. Further, we also used mNGS data to analyze for the first time the characteristic differences in the lower respiratory tract microbiota of patients with and without chlamydial pneumonia, the impact of the pattern of Chlamydia infection on the lower respiratory tract microbiota, and the clinical relevance of these characteristics. Significantly different profiles of lower respiratory tract microbiota and microecological diversity were found among different clinical subgroups, and in particular, mixed infections with C. psittaci and C. abortus resulted in lower lung microbiota diversity, suggesting that chlamydial infections shape the unique lung microbiota pathology, while mixed infections with different Chlamydia may have important effects on the composition and diversity of the lung microbiota.

Discussion

The present study provides possible evidences supporting the close correlation between chlamydial infection, altered microbial diversity in patients' lungs and clinical parameters associated with infection or inflammation in patients, which also provides a new research direction to better understand the pathogenic mechanisms of pulmonary infections caused by Chlamydia.

Distribution of drug-resistant genes in alveolar lavage fluid from patients with psittacosis and traceability analysis of causative organisms

Background

Chlamydia psittaci is a small bacterium often found in birds, including poultry, and domesticated mammals, which causes psittacosis (or parrot fever) in humans. Different strains of C. psittaci respond variably to antibiotics, suggesting a possible risk of antibiotic resistance. In general, different genotypes of C. psittaci have relatively stable hosts and different pathogenicity.

Methods

Macrogenomic sequencing was performed using nucleic acids extracted from psittacosis patients' alveolar lavage fluid samples and analyzed for genetic variability and antibiotic resistance genes. Nucleic acid amplification sequences specific to the core coding region of the C. psittaci ompA gene were used, and a phylogenetic tree was constructed with C. psittaci genotypic sequences from other sources, including Chinese published sources. The C. psittaci found in each patient were genotyped by comparing ompA gene sequences. In addition, to better illustrate the relationship between genotype and host of C. psittaci, 60 bird fecal samples were collected from bird-selling stores for screening and C. psittaci typing.

Results

Macrogenomic sequence alignment revealed the presence of resistance genes in varying abundance in samples from all three patients, including C. psittaci resistance gene sequences from two patients that matched those previously published on NCBI. Based on ompA genotyping, two patients were infected with C. psittaci genotype A and one patient was infected with genotype B. All five C. psittaci-positive samples obtained from bird-selling stores were genotype A. Both genotypes are reported to be infectious to humans. The host origin of the samples and the previously reported main sources of each genotype suggested that all but one of the C. psittaci genotype A in this study were derived from parrots, while genotype B was probably derived from chickens.

Conclusion

The presence of bacterial resistance genes in psittacosis patients may affect the efficacy of clinical antibiotic therapy. Focusing on the developmental progression of bacterial resistance genes and differences in the therapeutic efficacy may facilitate effective treatment of clinical bacterial infections. Pathogenicity genotypes (e.g., genotype A and genotype B) are not limited to one animal host, suggesting that monitoring the development and changes of C. psittaci may help prevent transmission to humans.

Clinical Characteristics of Six Patients with Chlamydia psittaci Infection Diagnosed by Metagenomic Next-Generation Sequencing: A Case Series

The incidence of psittacosis infection has gradually increased in recent years. Metagenomic next-generation sequencing (mNGS) can be used to comprehensively identify the total DNA and RNA content of the microbiome, as well as identify both known and unexpected pathogens within 24 hours. We diagnosed and treated six patients with psittacosis infection using mNGS, two of whom developed severe disease and most of whom presented with pulmonary symptoms. One of the young female patients also presented with irregular vaginal bleeding and myocarditis. Patients with underlying gastric disorders first showed gastrointestinal symptoms, which is a rare manifestation in patients with psittacosis. Older patients with underlying disease usually showed more severe symptoms. However, rare complications can also occur in immunocompetent young people and develop into severe disease. All patients showed significant congestion at bronchial lumen lesions, which may be associated with a severe inflammatory response to mucosal Chlamydia psittaci (C. psittaci) infection. Overall, mNGS is a rapid and effective tool for the clinical diagnosis of psittacosis caused by C. psittaci, and early diagnosis and treatment can prevent psittacosis from developing into a serious illness.

Psittacosis Pneumonia: Diagnosis, Treatment and Interhuman Transmission

Psittacosis pneumonia is a zoonosis caused by Chlamydia psittacosis infection, mainly resulting from contact with aerosols of birds or poultry's urine, feces, and excrement. The clinical manifestations range from general symptoms of infection to severe acute respiratory syndrome and systemic diseases, currently diagnosed using metagenomic next-generation sequencing (mNGS) to improve diagnostic accuracy. To date, most reports have only discussed human exposure to poultry disease. However, the latest studies have shown that human-to-human transmission of Chlamydia psittaci occurs not only between infected patients and their close contacts but also between secondary contacts. After looking back on relevant literature at home and abroad in the past ten years, this paper reviews the diagnosis, diagnosis and treatment, and progress in epidemiological research of Psittacosis pneumonia.

Comparison of clinical, laboratory and radiological characteristics between Chlamydia psittaci and adenovirus pneumonias: a multicenter retrospective study

OBJECTIVES

Pneumonia caused by Chlamydia psittaci is a significant global public health issue. Symptom onset and laboratory characteristics may be confused with those of other respiratory viral infections, including adenovirus pneumonia. We aimed to determine differences in clinical presentations and establish a simple nomogram to differentiate C. psittaci and adenovirus pneumonias.

METHODS

We conducted a multicenter retrospective study in 10 tertiary general hospitals to compare patients with either C. psittaci (n = 78) or adenovirus (n = 102) pneumonia. A multivariable logistic regression model was used to identify risk factors of C. psittaci pneumonia that were used to establish a nomogram.

RESULTS

C. psittaci and adenovirus pneumonia showed certain similar clinical symptoms, including fever, dyspnea, and fatigue, but differed in other characteristics. The multivariate logistic regression showed that age, sex, nervous system symptoms, lymphocyte count, C-reactive protein level, and bilateral lung lesions were risk factors for C. psittaci pneumonia. After incorporating these six factors, the established nomogram achieved a good concordance value (0.949 [95% CI 0.917-0.982]) in differentiating the types of pneumonia, with well-fitting calibration curves.

CONCLUSION

Despite having similar clinical features, the variables of age, sex, nervous system symptoms, lymphocytes, C-reactive protein levels, and bilateral lung lesions were combined into a clinically useful nomogram for the rapid and early differentiation of C. psittaci pneumonia from adenovirus pneumonia. This nomogram may help improve treatments and clinical outcomes.

Three Cases of Atypical Pneumonia with Chlamydia psittaci: The Role of Laboratory Vigilance in the Diagnosis of Psittacosis

Chlamydia psittaci is an established zoonotic agent causing respiratory disease in humans. An infection often remains asymptomatic but can also result in flu-like illness, pneumonia or even multi-organ failure. This paper describes three patients, hospitalised at AZ Sint-Lucas Hospital, with atypical pneumonia who were diagnosed with C. psittaci after an in-depth anamnesis and laboratory investigation in the midst of the COVID pandemic. All three infections were confirmed with PCR and serology, whereas viable bacteria were only present for one patient. Genotyping revealed the presence of genotype B for patient 1 and 2 whereas ompA genotyping was unsuccessful for patient 3. This case report demonstrates the importance of a thorough patient history as close contact with birds is one of the main risk factors to contract the pathogen. Once exposure to birds has been confirmed, a diagnosis by a combination of PCR and serology is essential in order to initiate a treatment with the proper antibiotics. As psittacosis is still an underestimated and underdiagnosed disease, communication between laboratory, clinicians and bird fanciers is encouraged.

Case Report: A Chlamydia psittaci pulmonary infection presenting with migratory infiltrates

Community-acquired pneumonia is a public health problem in all countries in the world, with a broad range of causative agents and Chlamydia psittaci infection tends to be overlooked. Pulmonary migratory infiltrates are commonly seen in eosinophilic pneumonia, cryptogenic organizing pneumonia, etc. However, the association of Chlamydia psittaci and pulmonary migratory infiltrates has been seldom described in literatures before. We reviewed a 64-year-old man referred to our hospital for treatment against Chlamydia psittaci pneumonia which was diagnosed by metagenomics next generation sequencing (mNGS). During the treatment period, chest imaging showed migratory infiltrates, which has been rarely described before.

Clinical diagnosis and etiology of patients with Chlamydia psittaci pneumonia based on metagenomic next-generation sequencing

The incidence of severe Chlamydia psittaci (C. psittaci) pneumonia and coinfections is increasing. Early detection of this condition is needed to prevent negative outcomes, along with detailed descriptions of its associated clinical characteristics. Our study contributes by undertaking etiological analysis of patients with C. psittaci pneumonia based on metagenomic next-generation sequencing (mNGS). A retrospective analysis of 30 patients with C. psittaci pneumonia was undertaken and confirmed by mNGS or polymerase chain reaction (PCR). Clinical manifestations of the severe and non-severe C. psittaci pneumonia groups were compared for clinical reference. Etiological analyses were also performed to comprehensively understand pathogeny and coinfection with other respiratory pathogens in C. psittaci patients. The absolute value of lymphocytes (LYM) in the severe group was lower than in the non-severe group. At the same time, neutrophil-to-lymphocyte ratio (NLR), procalcitonin (PCT), alanine aminotransferase (ALT), D-II polymer, brain natriuretic peptide (BNP), myoglobin (MYO), and cardiac troponin I (cTnI) were significantly higher (P < 0.05) in the severe group. mNGS has a broader pathogen spectrum and can more sensitively detect C. psittaci and other low-abundance pathogens with a higher positive detection rate (100%, 13/13 vs. 46%, 6/13, P <0.05) than conventional culture methods. mNGS detected the following dominant species associated with C. psittaci in patients: bacteria (53.2%, 39% gram-positive, 61% gram-negative), fungi (12.9%), and viruses (33.9%). A total of 73.3% (11/15) of patients had suspected coinfections, with a coinfection rate of 91.7% (11/12) in the severe group. No coinfection or death occurred in the non-severe group. Prognosis in the severe group was poor, with a mortality rate of 27.3% (3/11) for patients with coinfection. Eight of 11 patients with coinfections (72.7%) recovered. In conclusion, the clinical symptoms of severe C. psittaci pneumonia manifested as abnormal inflammatory indicators, impaired liver function, myocardial injury, coagulation, and relatively low immune responses. The higher proportion of patients with coinfections in our study supports the use of mNGS for comprehensive early detection of respiratory infections in patients with C. psittaci pneumonia. Simultaneous early identification of coinfections would further improve the clinical treatment of these patients.

Omadacycline for the Treatment of Severe Chlamydia psittaci Pneumonia Complicated with Multiple Organ Failure: A Case Report

Psittacosis is a rare zoonotic disease caused by Chlamydia psittaci infection, and tetracyclines are the preferred treatment. Omadacycline is a novel tetracycline that has a strong in vitro antibacterial activity against atypical pathogens, including C. psittaci; however, clinical data for its usage are lacking. We report a patient with severe C. psittaci-induced pneumonia presenting with a high fever, muscle aches, severe hepatic and renal insufficiency, and acute respiratory failure requiring tracheal intubation and mechanical ventilation. The condition was diagnosed using metagenomic next-generation sequencing. The patient was discharged after treatment with omadacycline. The findings of this study suggest that metagenomic next-generation sequencing is valuable for the rapid and accurate diagnosis of psittacosis. With its good safety profile and no requirement for dose adjustment in special populations, omadacycline is a new option for the treatment of severe C. psittaci pneumonia. However, additional case reports are needed to support this conclusion.

Host inflammatory response is the major factor in the progression of Chlamydia psittaci pneumonia

Purpose

Chlamydia psittaci (C. psittaci) has caused sporadic, but recurring, fatal community-acquired pneumonia outbreaks worldwide, posing a serious threat to public health. Our understanding of host inflammatory responses to C. psittaci is limited, and many bronchitis cases of psittaci have rapidly progressed to pneumonia with deterioration.

Methods

To clarify the host inflammatory response in psittacosis, we analyzed clinical parameters, and compared transcriptomic data, concentrations of plasma cytokines/chemokines, and changes of immune cell populations in 17 laboratory-confirmed psittacosis cases, namely, 8 pneumonia and 9 bronchitis individuals, in order to assess transcriptomic profiles and pro-inflammatory responses.

Results

Psittacosis cases with pneumonia were found to have abnormal routine blood indices, liver damage, and unilateral pulmonary high-attenuation consolidation. Transcriptome sequencing revealed markedly elevated expression of several pro-inflammatory genes, especially interleukins and chemokines. A multiplex-biometric immunoassay showed that pneumonia cases had higher levels of serum cytokines (G-CSF, IL-2, IL-6, IL-10, IL-18, IP-10, MCP-3, and TNF-α) than bronchitis cases. Increases in activated neutrophils and decreases in the number of lymphocytes were also observed in pneumonia cases.

Conclusion

We identified a number of plasma biomarkers distinct to C. psittaci pneumonia and a variety of cytokines elevated with immunopathogenic potential likely inducing an inflammatory milieu and acceleration of the disease progression of psittaci pneumonia. This enhances our understanding of inflammatory responses and changes in vascular endothelial markers in psittacosis with heterogeneous symptoms and should prove helpful for developing both preventative and therapeutic strategies.