Complete genome sequence of Chlamydia psittaci NRM_5 strain isolated from the fecal samples of a wild Indian ring-necked parakeet (Psittacula krameri manillensis) in Japan

We report here the whole-genome sequence of the Chlamydia psittaci NRM_5 strain isolated from the fecal samples of wild Indian ring-necked parakeet (Psittacula krameri manillensis) in Japan. The sequence type is ST35, which is known to be associated with pigeons and doves, indicating the potential for transmission among bird species.

Examining Intercage Transmission of Chlamydia muridarum : Impact of Barrier Husbandry and Cage Sanitization

Chlamydia muridarum (Cm) has reemerged as a prevalent bacterial contaminant of academic research mouse colonies. A study was conducted to assess the effectiveness of husbandry and cage sanitization methods in preventing intercage transmission of Cm. To assess intercage transmission during cage change, a cage housing 2 Cm-free Swiss Webster (Tac:SW; SW) sentinel mice was placed randomly on each of 12 individually ventilated cage racks, housing cages with Cm-shedding mice, located in 1 of 2 animal holding rooms. Husbandry staff blinded to the study cages, changed all cages in the animal holding rooms weekly using microisolator cage technique. PCR testing performed 180 days post-placement confirmed all mice remained negative for Cm. To assess the effectiveness of cage sanitization to eliminate Cm, we investigated transmission of Cm to a naïve Cm-free SW and NOD.Cg- Prkdc scid Il2rg tm1Wjl /SzJ (NSG) mouse co-housed for 7 days (repeated weekly for 4 weeks) in cages assigned to 1 of 3 groups (n=10 pairs of mice/group). Cages that previously housed 2 Cm-shedding BALB/c mice were either washed in a tunnel washer (82.2°C [180°F] final rinse for an average of 16 seconds per run; n=10) with and without post-washing autoclaving (121°C for 20 minutes; n=10), or were untreated (bedding change only; n=10). Pre- and post-sanitization swabs of each cage were assayed for Cm by PCR. All pre-treatment swabs tested positive, while post-treatment swabs from all cages (excluding bedding change) tested negative. All SW and NSG mice, irrespective of group, remained negative for Cm as determined by PCR. These findings suggest that infectious Cm does not persist in untreated cages nor after mechanical washing with and without autoclaving. Collectively, these findings suggest that neither our husbandry protocols nor inadequate cage sanitization methods likely contributed to the observed prevalence of Cm in contemporary research mouse colonies.

Type B3 thymoma complicated with Chlamydia psittaci pneumonia with rare features: A case report

The case of a patient with type B3 thymomacomorbid with Chlamydia psittaci (C. psittaci) pneumonia exhibiting rare features is presented in the current report. The patient was admitted at the Second Affiliated Hospital of Jiaxing University (Jiaxing, China) with a history of direct contact with poultry. Clinical manifestations included fever, shivers, cough, fatigue and poor appetite. Chest computed tomography (CT) indicated right lung pneumonia, while metagenomics next-generation sequencing using bronchoalveolar lavage fluid confirmed infection with C. psittaci. Additionally, positron emission tomography-CT suggested the presence of thymoma. After surgery and treatment with doxycycline and imipenem cilastatin, the patient was discharged showing signs of improvement.

Pneumonia Caused by Chlamydia psittaci and SARS-CoV-2 Coinfection Diagnosed Using Metagenomic Next-Generation Sequencing: A Case Report

We report a case of pneumonia caused by coinfection with Chlamydia psittaci and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron XBB.1 variant, confirmed using metagenomic next-generation sequencing (mNGS) and quantitative polymerase chain reaction (qPCR). C. psittaci and SARS-CoV-2 were detected in bronchoalveolar lavage fluid using mNGS. Additionally, mNGS detected C. psittaci in blood and nasopharyngeal specimens and was more sensitive than qPCR. The patient recovered after treatment with moxifloxacin. This report highlights the use of coinfections of C. psittaci and SARS-CoV-2, as mNGS has already been recognized to be a diagnostic tool for identifying coinfections.

Case Report: Pneumonia Caused by Chlamydia Psittaci and Cryptococcus Co-Infection

This study presents a rare case of pneumonia caused by a co-infection of Chlamydia psittaci and Cryptococcus, confirmed by metagenomic next-generation sequencing (mNGS). The patient, who had underlying chronic hepatitis B, had adopted a stray pigeon before the onset of the disease. The primary symptoms were fever, and a productive cough. The patient recovered following treatment with moxifloxacin and itraconazole. C. psittaci and Cryptococcus infections may both have been transmitted from the stray pigeon. This report highlights the potential for infections caused by multiple zoonotic pathogens and the value of mNGS for making the diagnosis of these infections.

Chlamydia psittaci infected cell studies by 4Pi Raman and atomic force microscopy

Chlamydia psittaci is an avian bacterial pathogen that can cause atypical pneumonia in humans via zoonotic transmission. It is a Gram-negative intracellular bacterium that proliferates inside membrane bound inclusions in the cytoplasm of living eukaryotic cells. The study of such cells with C. psittaci inside without destroying them poses a significant challenge. We demonstrated in this work the utility of a combined multitool approach to analyze such complex samples. Atomic force microscopy was applied to obtain high-resolution images of the surface of infected cells upon entrance of bacteria. Atomic force microscopy scans revealed the morphological changes of the cell membrane of Chlamydia infected cells such as changes in roughness of cell membrane and the presence of micro vesicles. 4Pi Raman microscopy was used to image and probe the molecular composition of intracellular bacteria inside intact cells. Information about the structure of the inclusion produced by C. psittaci was obtained and it was found to have a similar molecular fingerprint as that of an intracellular lipid droplet but with less proteins and unsaturated lipids. The presented approach demonstrates complementarity of various microscopy-based approaches and might be useful for characterization of intracellular bacteria.

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.

Bacterial communities along parrot digestive and respiratory tracts: the effects of sample type, species and time

Digestive and respiratory tracts are inhabited by rich bacterial communities that can vary between their different segments. In comparison with other bird taxa with developed caeca, parrots that lack caeca have relatively lower variability in intestinal morphology. Here, based on 16S rRNA metabarcoding, we describe variation in microbiota across different parts of parrot digestive and respiratory tracts both at interspecies and intraspecies levels. In domesticated budgerigar (Melopsittacus undulatus), we describe the bacterial variation across eight selected sections of respiratory and digestive tracts, and three non-destructively collected sample types (faeces, and cloacal and oral swabs). Our results show important microbiota divergence between the upper and lower digestive tract, but similarities between respiratory tract and crop, and also between different intestinal segments. Faecal samples appear to provide a better proxy for intestinal microbiota composition than the cloacal swabs. Oral swabs had a similar bacterial composition as the crop and trachea. For a subset of tissues, we confirmed the same pattern also in six different parrot species. Finally, using the faeces and oral swabs in budgerigars, we revealed high oral, but low faecal microbiota stability during a 3-week period mimicking pre-experiment acclimation. Our findings provide a basis essential for microbiota-related experimental planning and result generalisation in non-poultry birds.

Pet safety guidelines for pediatric transplant recipients

Approximately 70% (90.5 million) of United States (US) households own at least one pet. Dogs are the most common, making up about 38% of all household pets, followed by cats, which make up 25%. Other pets such as fish, birds, reptiles, and small animals such as hamsters, gerbils, and rabbits are less common household members. Pets are often considered a part of the family and there are significant medical and psychosocial benefits to pet ownership; however, the possibility of disease transmission exists related to the type of animal and infectious organism, and specific human risk factors. Immunocompromised individuals may be at increased risk of serious illness from zoonotic infections. During the transplant evaluation and routinely posttransplant, the multidisciplinary team should inquire about pet ownership and animal exposures to guide on potential risks. This review discusses the most common diseases seen in various household pets including dogs, cats, birds, fish, and some farm animals. We will also present guidelines for pet safety and include strategies to decrease the risk of infection while supporting the benefits of pet ownership after transplant.

Belgian Cross-Sectional Epidemiological Study on Zoonotic Avian Chlamydia spp. in Chickens

Chlamydia psittaci, Chlamydia gallinacea, and Chlamydia abortus are the most common Chlamydia spp. in chickens and have a confirmed or suggested zoonotic potential. No recent data are available on their prevalence and impact in the Belgian chicken industry or in the recreational chicken branch. Therefore, a cross-sectional epidemiological study was executed where samples were collected from both factory-farmed and backyard chickens. More specifically, pharyngeal chicken swabs were obtained from 20 chicken farms, 5 chicken abattoirs, and 38 different backyard locations and were analyzed using species-specific Polymerase Chain Reactions (PCRs) for the presence of the three avian Chlamydia spp. To investigate their zoonotic potential, samples were simultaneously collected from 54 backyard chicken caretakes and 37 professional chicken caretakers or abattoir employees and analyzed using species-specific PCRs as well. This study confirmed the presence of DNA of all three Chlamydia species in both the chicken industry and backyard settings. Chlamydia psittaci was the most prevalent in the industry chickens (11.0%), whereas Chlamydia gallinacea was the dominant species in the backyard chickens (14.5%). Chlamydia abortus infections were more common in the commercial chickens (9.0%) compared to the backyard chickens (2.6%). The DNA of all three species was also detected in humans (3.9% Chlamydia psittaci, 2.9% Chlamydia gallinacea, and 1.0% Chlamydia abortus).

Omadacycline for the treatment of severe pneumonia caused by Chlamydia psittaci complicated with acute respiratory distress syndrome during the COVID-19 pandemic

Introduction

Chlamydia psittaci infection in humans is a rare cause that mainly present as community-acquired pneumonia. Severe Chlamydia psittaci pneumonia can lead to acute respiratory distress syndrome (ARDS), septic shock, or multiple organ dysfunction with a mortality rate of 15%-20% before accurate diagnosis and targeted treatment. Metagenomic next-generation sequencing (mNGS) has an advantage in achieving early diagnosis. In the study, omadacycline implementation was described to provide a better understanding of effectiveness in severe psittacosis pneumonia with ARDS.

Methods

Sixteen patients with severe psittacosis pneumonia with ARDS were selected between September 2021 and October 2022. They were diagnosed using mNGS and treated with omadacycline. Retrospective analysis of clinical manifestations, laboratory data, disease progression, diagnostic tool, treatment, and prognosis was summarized.

Results

Common symptoms included fever, dyspnea, and cough. All patients developed ARDS, accompanied by septic shock (43.7%) and pulmonary embolism (43.7%). Laboratory data showed normal leucocytes, increased creatine kinase isoenzyme, and decreased albumin with liver dysfunction in most patients. All patients had increased neutrophils, C-reactive protein, procalcitonin, and D-dimer with decreased lymphocytes. Airspace consolidation, ground glass opacity, and pleural effusion were found on chest CT. mNGS results were obtained in 24-48 h to identify the diagnosis of Chlamydia psittacosis. All patients received mechanical ventilation with omadacycline treatment. Fourteen patients experienced complete recovery, while the other two patients died from multidrug-resistant bacterial infection and renal failure.

Conclusion

mNGS has a significant value in the diagnosis of Chlamydia psittaci infection. Timely treatment of omadacycline can improve prognosis and provide a promising new option for the treatment of severe Chlamydia psittaci pneumonia with ARDS.

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.

Diagnosis and Surgical Treatment of a Renal Cyst Causing Unilateral Lameness in a Golden Eagle (Aquila chrysaetos)

This report describes the diagnosis and treatment of a benign renal cyst in an adult, female golden eagle (Aquila chrysaetos) presented for unilateral leg lameness. A cyst at the cranial division of the left kidney was diagnosed by computed tomography and was suspected of compressing the lumbosacral nerve plexus, resulting in limb lameness. The renal cyst was incompletely excised because the cyst wall was closely adhered to the kidney parenchyma and local blood supply. Fluid analysis and surgical biopsy of the cyst and left kidney confirmed the diagnosis of a benign renal cyst. No evidence of an infectious, inflammatory, or neoplastic etiology was noted. Postoperatively, the eagle's lameness resolved and the bird was ultimately released following recovery. During treatment for the renal cyst, the eagle was concurrently found to have increased serum titers on elementary body agglutination for Chlamydia psittaci and a positive titer for Aspergillus species antibody testing. The bird was administered doxycycline, azithromycin, and voriconazole for treatment of these potential pathogens prior to release. Unfortunately, the eagle was found dead 86 days postrelease due to an unknown cause. To the authors' knowledge, this is the first report of a golden eagle with a benign solitary renal cyst causing unilateral lameness secondary to nerve compression that was resolved with surgical excision.

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.

Clinical features of psittacosis in 46 Chinese patients

BACKGROUND

Psittacosis is a relatively uncommon cause of community-acquired pneumonia, often leading to diagnostic difficulty.

METHODS

A retrospective study was conducted on the clinical features of psittacosis patients in China. Forty-six cases of Chlamydophila psittaci infection with atypical pneumonia of varying severity in the last two years were described retrospectively.

RESULTS

Fever, relative bradycardia, and other systemic upsets were the main clinical presentation. The most common radiographic abnormality was segmental or lobar shadowing or consolidation. The total white cell counts were usually normal or slightly increased. The concentration of creatine kinase, C reactive protein, and lactic dehydrogenase increased, while albumin decreased remarkably. These cases exhibited good recovery after being treated with tetracycline or quinolone antibiotics.

CONCLUSION

These features may help differentiate psittacosis from other traditional bacterial pneumonia. However, they do not provide a definitive diagnosis. Psittacosis diagnosis must perform the whole-genome sequencing for Chlamydophila psittaci in respiratory, blood, or sputum specimens. Increased awareness of psittacosis can shorten diagnostic delays and improve patient outcomes.

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.

Co-infection of Chlamydia psittaci and Tropheryma whipplei: A case report

BACKGROUND

The co-infection of Chlamydia psittaci (C. psittaci) and Tropheryma whipplei (T. whipplei) is unusual, and the detection of pathogenic microorganisms is particularly important for patients with severe diseases or poor experience in treatment. Early identification of pathogens can significantly improve the prognosis of the patients. Targeted next-generation sequencing (tNGS) is currently widely used in clinical practice for various infectious diseases, including respiratory infections, to achieve early, accurate, and rapid microbial diagnosis.

CASE SUMMARY

We report a case of a 40-year-old female patient with a history of contact with parrots who was diagnosed with C. psittaci and T. whipplei infection through bronchial lavage fluid targeted next generation sequencing. After moxifloxacin treatment, the patient's symptoms improved significantly, and the imaging changes were obviously resolved.

CONCLUSION

Coinfection with C. psittaci and T. whipplei is not common. In this case, timely and accurate identification of both pathogens was achieved using tNGS. Moreover, the efficacy of monotherapy with moxifloxacin was confirmed.

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.

Successful treatment of near-fatal pulmonary embolism and cardiac arrest in an adult patient with fulminant psittacosis-induced severe acute respiratory distress syndrome after veno-venous extracorporeal membrane oxygenation rescue: A case report and follow-up

Background

Veno-venous extracorporeal membrane oxygenation (ECMO) was successfully performed for the rescue of an adult patient with severe acute respiratory distress syndrome (ARDS) induced by fulminant psittacosis, and then a near-fatal pulmonary embolism (PE) and cardiac arrest (CA) of the same patient was cured through catheter-directed thrombolysis.

Case presentation

A 51-year-old female patient was admitted to the hospital on September 10, 2021 due to slurred speech, weakness in lower limbs, dizziness, and nausea. Subsequently, she developed confusion and was transferred to the intensive care unit (ICU), where she received anti-shock, antibiotics, invasive mechanical ventilation (IMV), and veno-venous ECMO due to the diagnosis of severe pneumonia, severe ARDS, and septic shock based on comprehensive physical examination, laboratory tests, and imaging findings. The metagenomic next-gengeration sequencing (m-NGS) in the bronchoalveolar lavage fluid (BALF) suggested that the pathogen was chlamydia psittaci, so the antibiotics were adjusted to doxycycline combined with azithromycin. After withdrawal from ECMO, ultrasound (US) re-examination of the left lower limb revealed inter-muscular vein thrombosis, following which heparin was replaced by subcutaneous injection of 0.4ml enoxaparin sodium twice daily for anti-coagulation therapy. After withdrawal from IMV, the patient suffered sudden CA and successful cardiopulmonary resuscitation (CPR), and emergency pulmonary angiography (PA) was performed to show bilateral main pulmonary artery embolism. After immediate catheter-directed thrombolysis and placement of an inferior vena cava filter, the patient's condition gradually stabilized.

Conclusions

Veno-venous ECMO can be successfully performed as an emergency life-saving treatment for patients with severe ARDS induced by fulminant psittacosis, and during ECMO regular examinations should be conducted to detect and manage thrombosis in time, thereby avoiding the occurrence of near-fatal PE and CA.

Chlamydia psittaci seropositivity in workers exposed to birds and review of the literature: Evidence of circulation in Antioquia

Introduction

Psittacosis is a zoonotic disease caused by Chlamydia psittaci, a bacterium classified as an agent with bioterrorist potential. It has caused multiple outbreaks in exposed poultry workers around the world. Colombia has no epidemiological follow-up of the infection and a big knowledge gap.

Objectives

To determine the antibodies’ frequency against C. psittaci in workers with occupational exposure to birds and to review the literature on studies conducted in Colombia.

Materials and methods

We conducted a cross-sectional descriptive study with analytical intent on workers in contact with birds and reviewed the related literature in Colombia. IgM and IgG serum antibodies against C. psittaci were detected by microimmunofluorescence. The sociodemographic and exposure characteristics were expressed as frequencies and summary measures. Associated factors were explored by bivariate and multivariate analysis. The scientific and gray literature review was done with a structured search.

Results

We analyzed 54 workers in contact with birds. Antibody prevalence was 31.5%. Slaughtering and evisceration by non-veterinarians was a risk factor for antibody presence. There are only four previous studies on C. psittaci in Colombia.

Conclusions

Here, we present the first evidence of C. psittaci circulation among workers exposed to birds in Antioquia and the second report in the country. These findings contribute to the “One Health” public health strategy.

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.

Epidemiological and clinical characteristics of psittacosis among cases with complicated or atypical pulmonary infection using metagenomic next-generation sequencing: a multi-center observational study in China

BACKGROUND

Chlamydia psittaci (C. psittaci) causes parrot fever in humans. Development of metagenomic next-generation sequencing (mNGS) enables the identification of C. psittaci.

METHODS

This study aimed to determine the epidemiological and clinical characteristics of parrot fever cases in China. A multi-center observational study was conducted in 44 tertiary and secondary hospitals across 14 provinces and municipalities between April 2019 and October 2021.

RESULTS

A total of 4545 patients with complicated or atypical pulmonary infection were included in the study, among which the prevalence of C. psittaci was determined to be 2.1% using mNGS. The prevalence of C. psittaci was further determined across demographic groups and types of specimens. It was significantly higher in patients with senior age (2.6% in those > 50 years), winter-spring (3.6%; particularly in December, January, and February), and southwestern (3.4%) and central and southern China (2.7%) (each P < 0.001). Moreover, the prevalence was the highest in bronchoalveolar lavage fluid (BALF) (2.9%), compared with sputum (1.1%) and peripheral blood specimens (0.9%). Additionally, co-infection of principal microorganisms was compared. Certain microorganisms were more likely to co-infect in parrot fever cases, such as Candida albicans in BALF (26.7%) and peripheral blood (6.3%), compared with non-parrot fever cases (19.7% and 1.3%); however, they did not significantly differ (each P > 0.05).

CONCLUSION

Parrot fever remains low in patients with complicated or atypical pulmonary infection. It is likely to occur in winter-spring and southwestern region in China. BALF may be the optimal specimen in the application of mNGS. Co-infection of multiple microorganisms should be further considered.

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

BACKGROUND

This 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 PRESENTATION

This 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).

CONCLUSIONS

Psittacosis 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.

Evaluation of a biosecurity survey approach for contamination by Chlamydia pecorum in koala rehabilitation, field capture, and captive settings

Transmission of Chlamydia pecorum between koalas is a potential risk in field capture or rehabilitation settings, where koalas are held in proximity to each other, or equipment is shared between animals. Given the impact of C. pecorum on koala welfare and population viability it is surprising that quarantine and disinfection protocols in a koala rehabilitation facility or capture settings have not previously been evaluated. This study aimed to evaluate an approach, based on the detection of chlamydial DNA and cell viability, to determine the degree of environmental contamination within a koala care facility. Various fomite sites associated with koala care at a koala rehabilitation facility in New South Wales, Australia were identified as potential sources of chlamydial contamination, following exposure to koalas known to be infected with C. pecorum. Fomite sites were swabbed following exposure, and again after decontamination procedures were carried out. Samples were tested for the presence of chlamydial DNA using qPCR and viability using both RT-qPCR and cell culture. From a total of 239 sampling events, 30 tested qPCR positive for chlamydial DNA, with 19 and 11 samples corresponding to pre-decontamination and post-decontamination events respectively. Detection of chlamydial DNA appeared to be most common in the examination room, especially on fomite sites in direct contact with koalas. Physical removal of chlamydial DNA, or its degradation by the elements, appeared to be more common on outdoor enclosures, clothing, and hands. Based on the cell culture assay, of the pre-decontamination samples with chlamydial DNA, eight had viable chlamydial cells, two of these at low levels. Of the post-decontamination samples with chlamydial DNA, one had a moderate number, and one had a very low number of viable chlamydial cells. RT-qPCR was unsuccessful in determining cell viability due to low yields of RNA and high levels of contaminants from the environmental samples. The outcomes of this study provide a knowledge base for the design of future biosecurity evaluation guidelines in captive and koala rehabilitation facilities. The higher incidence of chlamydial DNA detection by qPCR than viable organism highlights the need to use viability assays in similar studies. However, further investment is still needed to optimise these methods and improve sensitivity for complex environmental samples.

Psittacosis caused severe community-acquired pneumonia accompanied by acute hypoxic respiratory failure: a multicenter retrospective cohort study from China

INTRODUCTION

Psittacosis can cause severe community-acquired pneumonia (CAP). The clinical manifestations of psittacosis range from subclinical to fulminant psittacosis with multi-organ failure. It is essential to summarize the clinical characteristic of patients with severe psittacosis accompanied by acute hypoxic respiratory failure (AHRF).

METHODS

This retrospective study included patients with severe psittacosis caused CAP accompanied by AHRF from 19 tertiary hospitals of China. We recorded the clinical data, antimicrobial therapy, respiratory support, complications, and outcomes. Chlamydia psittaci was detected on the basis of metagenomic next-generation sequencing performed on bronchoalveolar lavage fluid samples. Patient outcomes were compared between the treatment methods.

RESULTS

This study included 45 patients with severe CAP and AHRF caused by psittacosis from April 2018 to May 2021. The highest incidence of these infections was between September and April. There was a history of poultry contact in 64.4% of the patients. The median PaO2/FiO2 of the patients was 119.8 (interquartile range, 73.2 to 183.6) mmHg. Four of 45 patients (8.9%) died in the ICU, and the median ICU duration was 12 days (interquartile range, 8 to 21) days. There were no significant differences between patients treated with fluoroquinolone initially and continued after the diagnosis, fluoroquinolone initially followed by tetracycline, and fluoroquinolone combined with tetracycline.

CONCLUSION

Psittacosis caused severe CAP seems not rare, especially in the patients with the history of exposure to poultry or birds. Empirical treatment that covers atypical pathogens may benefit such patients, which fluoroquinolones might be considered as an alternative.

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.

Equine Psittacosis and the Emergence of Chlamydia psittaci as an Equine Abortigenic Pathogen in Southeastern Australia: A Retrospective Data Analysis

Chlamydia psittaci is an important zoonotic pathogen. Although primarily a pathogen of birds, from which infection can spillover into humans and other mammalian hosts, the importance of C. psittaci as a cause of equine reproductive loss and the risk of infection to humans in contact with infected horses are increasingly being recognised in Australia and elsewhere. Despite the risks to both human and equine health, C. psittaci infection in horses is incompletely understood. This study aimed to update and summarise cases of equine psittacosis in Australia in the period 2018-2022, thus addressing a knowledge gap relating to recent cases in this country. These cases were identified from the examination of records held by state and federal veterinary authorities and from a review of published cases. A total of 31 cases were identified. Spatial and temporal trends were identified, with cases being more prevalent in winter and spring and geographically restricted to Victoria and New South Wales. The results show that cases of equine reproductive loss due to C. psittaci are consistent and ongoing and demonstrate the importance of routinely considering C. psittaci in diagnostic investigations. The need for ongoing study to better understand this important zoonotic pathogen is evident.

Multiplex Real-time PCR Assay for the Detection of all Chlamydia Species and Simultaneous Differentiation of C. psittaci and C. pneumoniae in Human Clinical Specimens

We developed and assessed the performance of a new multiplex real-time PCR assay for the detection of all Chlamydia species and simultaneous differentiation of Chlamydia psittaci and Chlamydia pneumoniae-two important human respiratory pathogens-in human clinical specimens. Next-generation sequencing was used to identify unique targets to design real-time PCR assays targeting all Chlamydia species, C. psittaci, and C. pneumoniae. To validate the assay, we used a panel of 49 culture isolates comprising seven C. psittaci genotypes, eight C. pneumoniae isolates, seven other Chlamydia species, and 22 near-neighbor bacterial and viral isolates, along with 22 specimens from external quality assessment (EQA) panels and 34 nasopharyngeal and oropharyngeal swabs and cerebrospinal fluid, stool, and sputum specimens previously identified as positive or negative for C. psittaci or C. pneumoniae. The assays were 100% specific, with limits of detection of 7.64- 9.02 fg/μL. The assay results matched with historical assay results for all specimens, except for one owing to the increased sensitivity of the new C. psittaci assay; the results of the EQA specimens were 100% accurate. This assay may improve the timely and accurate clinical diagnosis of Chlamydia infections and provide a greater understanding of the burden of disease caused by these agents.

Chlamydia Psittaci Pneumonia-Induced Myocarditis: A Case Report

The incidence of Chlamydia psittaci infection has been reported to increase in recent years. The presentation of psittacosis infection varied widely, from none to severe symptoms. Mainly, psittacosis infection presents with pulmonary manifestations. Here, we report the case of a 60-year-old female patient with Chlamydia psittaci pneumonia complicated by myocarditis. After administering antibiotics, the patient recovered from severe atypical pneumonia and myocarditis. In general, Chlamydia psittaci rarely induces myocarditis. Moreover, the optimal therapeutic strategies remain unclear for such cases, especially with a high troponin T level. Metagenomic Next-Generation Sequencing (mNGS) can provide a quick and effective diagnosis of Chlamydia psittaci pneumonia; early intervention (antibiotic therapy and nutritional supplements for myocarditis) favors a good outcome, although complications may worsen the condition. Therefore, more studies are required to help improve understanding of the disease.

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.

Extracorporeal Membrane Oxygenation in Severe Acute Respiratory Distress Syndrome Caused by Chlamydia abortus: A Case Report

Background

Pneumonia infected by Chlamydia abortus (C. abortus) is rare, especially complicated with severe acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS).

Case Presentation

We presented the clinical details of a 44-year-old male who was diagnosed with C. abortus pneumonia, which rapidly progressed and ultimately led to ARDS, sepsis and MODS. Although he was initially diagnosed with pneumonia upon admission, no pathogenic bacteria were detected in sputum by conventional tests. Empirical intravenous infusion of meropenem and moxifloxacin was administered, but unfortunately, his condition deteriorated rapidly, especially respiratory status. On Day 2 after extracorporeal membrane oxygenation (ECMO) initiation, metagenomic next-generation sequencing (mNGS) was performed on the patient's bronchoalveolar lavage fluid, which indicated an infection with C. abortus. The patient's antimicrobial therapy was adjusted to oral doxycycline (0.1g every 12h), intravenous azithromycin (0.5g every day), and imipenem and cilastatin sodium (1g every 6h). The patient's condition improved clinically and biologically. However, the patient was discharged due to financial reasons and unfortunately passed away eight hours later.

Conclusion

Infections with C. abortus can result in severe ARDS and serious visceral complications which necessitate prompt diagnosis and active intervention by clinicians. The case highlights the significance of mNGS as an essential diagnostic tool for uncommon pathogens. Tetracyclines, macrolides or their combinations are effective choices for treatment of C. abortus pneumonia. Further study is needed to explore the transmission routes of C. abortus pneumonia and establish precise guidelines for antibiotic treatment.

Gestational psittacosis causes severe pneumonia and miscarriage: A case report and literature review

Psittacosis is an uncommon zoonotic illness, and gestational psittacosis is even rarer. The clinical signs and symptoms of psittacosis are varied, often overlooked, and swiftly identified by metagenomic next-generation sequencing. We recorded the case of a 41-year-old pregnant woman with psittacosis where the disease was not detected early on, resulting in severe pneumonia and fetal miscarriage. The clinical symptoms, diagnosis, and treatment of psittacosis in pregnancy are the subject of this case study.

Physcion, a novel anthraquinone derivative against Chlamydia psittaci infection

Physcion, a natural anthraquinone derivative, has been reported to exert remarkable antibacterial activities against Staphylococcus aureus,Staphylococcus epidermidis and Pseudomonas aeruginosa. However, it is not fully illustrated as anti-Chlamydia substance. In the present study, minimum inhibitory concentration(MIC)values for physcion against Chlamydia psittaci(C.psittaci) 6BC, C.psittaci SBL and C.psittaci HJ were 128 μg/mL,256 μg/mL and 128 μg/mL while minimum bactericidal concentration (MBC) values were 256 μg/mL,512 μg/mL and 256 μg/mL,respectively. Moreover, Chlamydial adhesion to Hela 229 cells was blocked in a dose-dependent manner and RB-to-EB differentiation was inhibited by physcion from 28 to 48 hpi.Post treatment,upregulation of LC3-II was in a dose-dependent manner, indicating physcion activated autophagy and bacterial clearance.To validate clinical efficacy,49 SPF chickens aged 21days were divided into 5 groups and infected intra-laryngeally with 0.2 mL of 1 × 10⁷ IFU/mL C.psittaci 6 BCE.Three days later, birds received orally with serial doses of physcion (4 mg/kg to 9 mg/kg), or 3 mg/kg of doxycycline for 6 days.Chickens with difficulty in breathing were alleviated significantly with increasing concentrations of physicon.Postmortem,lesions of air sacs were reduced significantly in a dose-dependent manner.More importantly,birds with 9 mg/kg of physcion could alleviate lesions of air sacs and lungs, and reduce bacterial loads in spleens, which was comparable to doxycycline treatment. Based on above evidences, physcion is a promising cost-effective natural drug by blocking Chlamydial adhesions to host cells, RB-to-EB differentiation and activating bacterial autophagy and it will be a good alternative to doxycycline combating virulent C.psittaci infection, contributing to eradication of Chlamydial transmission from animals to human beings.

Microbiological diagnostic performance of metagenomic next-generation sequencing compared with conventional culture for patients with community-acquired pneumonia

Background

Community-acquired pneumonia (CAP) is an extraordinarily heterogeneous illness, both in the range of responsible pathogens and the host response. Metagenomic next-generation sequencing (mNGS) is a promising technology for pathogen detection. However, the clinical application of mNGS for pathogen detection remains challenging.

Methods

A total of 205 patients with CAP admitted to the intensive care unit were recruited, and broncho alveolar lavage fluids (BALFs) from 83 patients, sputum samples from 33 cases, and blood from 89 cases were collected for pathogen detection by mNGS. At the same time, multiple samples of each patient were tested by culture. The diagnostic performance was compared between mNGS and culture for pathogen detection.

Results

The positive rate of pathogen detection by mNGS in BALF and sputum samples was 89.2% and 97.0%, which was significantly higher (P < 0.001) than that (67.4%) of blood samples. The positive rate of mNGS was significantly higher than that of culture (81.0% vs. 56.1%, P = 1.052e-07). A group of pathogens including Mycobacterium abscessus, Chlamydia psittaci, Pneumocystis jirovecii, Orientia tsutsugamushi, and all viruses were only detected by mNGS. Based on mNGS results, Escherichia coli was the most common pathogen (15/61, 24.59%) of non-severe patients with CAP, and Mycobacterium tuberculosis was the most common pathogen (21/144, 14.58%) leading to severe pneumonia. Pneumocystis jirovecii was the most common pathogen (26.09%) in severe CAP patients with an immunocompromised status, which was all detected by mNGS only.

Conclusion

mNGS has higher overall sensitivity for pathogen detection than culture, BALF, and sputum mNGS are more sensitive than blood mNGS. mNGS is a necessary supplement of conventional microbiological tests for the pathogen detection of pulmonary infection.

Prevalence and Risk Factors of Avian Chlamydiosis Detected by Polymerase Chain Reaction in Psittacine Birds in Thailand

This study surveyed avian chlamydiosis, with the aim to estimate the prevalence and potential risk factors associated with Chlamydia psittaci infection in psittacine birds kept as domestic pets in Thailand. Oropharyngeal swabs were collected from 120 psittacine birds that were randomly selected from hospitals in the central (Bangkok) and northeastern regions (Khon Kaen) of Thailand between 2019 and 2021. The oropharyngeal swabs were subject to polymerase chain reaction testing to detect the C psittaci ompA gene. The prevalence of C psittaci was 2.5% (3/ 120, 95% confidence interval = 0.3-5.3). Of the 3 positive birds, 1 was a Forpus parrot (Forpus species)(CP43TH) and 1 was an African grey parrot (Psittacus erithacus)(CP49TH) from Bangkok; both were juvenile birds with clinical signs of disease. The third positive bird (CP12TH) was a subclinical adult sun conure (Aratinga solstitialis) from Khon Kaen. Two sequences of samples that were previously identified in human psittacosis cases (accession numbers MK032053.1 and HM450409.1) were also examined. Since there was a low number of infected birds, potential associations between C psittaci infection and various environmental variables (eg, cage cleaning, synanthropic birds, quarantine of new birds, and overcrowding) were assessed by Fisher exact tests. This study provides estimates of the prevalence and potential risk factors associated with C psittaci infection in psittacine birds from central (Bangkok) and the northeastern regions (Khon Kaen) of Thailand. The detection of C psittaci in captive psittacine birds demonstrates that there is a possibility for bird-to-bird transmission as well as some zoonotic potential for the human caretakers of these birds. Furthermore, larger-scale studies should be conducted to confirm these findings.

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.

Physiological analysis of severe chlamydia psittaci pneumonia and clinical diagnosis after doxycycline-based treatment

Objective: To describe the clinical spectrum of severe Chlamydia psittaci pneumonia in order to understand the disease better. Methods: Retrospective analysis was made on 31 patients with severe Chlamydia psittaci pneumonia diagnosed in ICU by next-generation sequencing of metagenome Metagenomic next-generation sequencing(mNGS) from January 2019-November 2022, including clinical characteristics, laboratory examination results, imaging characteristics, treatment, and prognosis. Results: We included 31 patients with severe Chlamydia psittaci pneumonia, 15 of whom had a history of virus exposure. There were 12 cases with multiple bacterial infections, and the common symptoms included fever (31/31,100%), dyspnea (31/31, 100%), cough (22/31, 71.0%), and myalgia (20/31, 64.5%). Laboratory data showed that white blood cells were average or slightly increased, but the levels of C-reactive protein and neutrophils were high. CT findings of the lung were consolidation (19/31, 61.3%) and pleural effusion (11/31, 35.5%). Only one lobe was involved in 11 patients (35.5%). Before diagnosis, 22 patients (71.0%) did not have atypical pathogens in their antimicrobial regimen. After diagnosis, 19 patients (61.3%) received single drug treatment, of which doxycycline or moxifloxacin were the most commonly used drugs. Among 31 patients, three died, nine improved, and nineteen were cured. Conclusion: The clinical manifestations of severe Chlamydia psittaci pneumonia are non-specific. The application of mNGS can improve the diagnostic accuracy of Chlamydia psittaci pneumonia, reduce the unnecessary use of antibiotics, and shorten the course of the disease. Doxycycline-based treatment is effective for severe chlamydia psittaci pneumonia, but it is necessary to understand the secondary bacterial infection and other complications in the course of the disease.

Case Report: Chlamydia psittaci pneumonia complicated by Guillain-Barré syndrome detected using metagenomic next-generation sequencing

Psittacosis and Guillain-Barré syndrome are both rare clinical diseases with low incidence, and their combination has rarely been reported. Here, we report a case of Chlamydia psittaci pneumonia combined with Guillain-Barré syndrome. The patient initially presented with high fever, difficulty breathing, and fatigue. Chest computerised tomography indicated large consolidation opacities in both lungs. Metagenomic next-generation sequencing clearly identified the pathogen as C. psittaci. The patient's fever subsided after targeted antibiotic treatment, but difficulty breathing and fatigue worsened, and the patient developed symmetric limb numbness and weakness. Lumbar puncture, electrophysiological examination, and clinical characteristics were suggestive of Guillain-Barré syndrome, and the symptoms improved after treatment with human immunoglobulin. The results of this study suggest that metagenomic next-generation sequencing is useful for the rapid diagnosis of pulmonary infectious agents. Psittacosis is closely associated with the development of Guillain-Barré syndrome; however, more cases are needed to support this conclusion, and early targeted antibiotic treatment, immunotherapy, and basic supportive treatment are essential for improving outcomes.

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.

Prostatitis as initial manifestation of Chlamydia psittaci pneumonia diagnosed by metagenome next-generation sequencing: A case report

Chlamydia psittaci (C. psittaci) pneumonia is a zoonotic infectious disease caused by C. psittaci, which is often underdiagnosed. The application of metagenomic next-generation sequencing (mNGS) provides an unbiased method for the detection of unknown pathogens. A 46-year-old man received empirical treatment with piperacillin-tazobactam and moxifloxacin after an initial diagnosis of prostatitis and pneumonia. However, he experienced recurrent symptoms and a cough, and a chest computed tomography (CT) showed aggravated pulmonary inflammation. Upon further questioning, the patient recalled a history of contact with pigeons, and a bronchoscope alveolar lavage fluid analysis with mNGS suggested C. psittaci infection. Following treatment with doxycycline, the patient's symptoms were rapidly alleviated, and chest CT showed pulmonary lesions absorption. The patient was followed up for 1 month without any discomfort. This case highlights that initial manifestations of C. psittaci pneumonia may present with atypical symptoms such as prostatitis. Furthermore, mNGS can be a useful tool for the detection of rare or unknown pathogens such as C. psittaci.

Chlamydia psittaci Pneumonia Complicated with Lower Extremity Atherosclerotic Occlusive Disease

Chlamydia is a zoonotic pathogen that mainly infects poultry and pet birds. This Gram-negative obligate intracellular parasite also causes human psittacosis, the severity of which varies from mild flu-like symptoms to life-threatening severe pneumonia, including sepsis, acute respiratory distress syndrome, and multiple organ failure. Inhalation of aerosols from contaminated bird excreta through the respiratory tract is the main route of transmission to humans. Here, we present a case of Chlamydia psittaci pneumonia accompanied by lower extremity atherosclerotic occlusive disease. A 48-year-old man was admitted to the emergency department with a four-day history of cough and dyspnea. A detailed history revealed his contact with domestic pigeons. The results of metagenomic next-generation sequencing of bronchoalveolar lavage fluid suggested C. psittaci infection. Antibacterial agents were switched to targeted doxycycline, but in the next week, skin examination revealed acrocyanosis of both lower extremities, and the remarkable palpable purpura progressively worsened. Re-examination of the lower extremity vascular ultrasound suggested left dorsalis pedis artery occlusion and right peroneal vein thrombosis, which resulted in the amputation of both legs. This case is the first report of C. psittaci pneumonia combined with arterioocclusive sclerosis of both lower extremities.

Clinical and chest computed tomography features associated with severe Chlamydia psittaci pneumonia diagnosed by metagenomic next-generation sequencing: A multicenter, retrospective, observational study

Chlamydia psittaci pneumonia is a rare disease with varying clinical presentations. Here, we aimed to investigate the clinical and chest computed tomography (CT) features of severe psittacosis pneumonia. Clinical data of 35 patients diagnosed with psittacosis pneumonia were retrospectively analyzed using metagenomic next-generation sequencing. The patients were classified into severe (n = 20) and non-severe (n = 15) groups. The median age of patients was 54 years, and 27 patients (77.1%) had a definite history of bird contact. Severe patients had more underlying comorbidities and were more prone to dyspnea and consciousness disorders than non-severe patients. The neutrophil count and D-dimer, lactate dehydrogenase, interleukin (IL)-2, IL-6, and IL-10 levels were higher, whereas the lymphocyte, CD3 + T cell, and CD4 + T cell counts, CD4+/CD8 + T cell ratio, and albumin level were substantially lower in severe patients than in non-severe patients. Chest CT findings of severe patients revealed large areas of pulmonary consolidation, and ground-glass opacities were observed in some patients, with a higher risk of involving multiple lobes of the lungs and pleural effusion. One patient died of multiple organ failure, whereas the condition of the other 34 patients improved, and they were discharged from the hospital. Patients with severe psittacosis pneumonia often have underlying comorbidities and are prone to developing dyspnea, consciousness disorder, and lesions in both lungs. Serum D-dimer, IL-2, IL-6, and IL-10 levels and lymphocyte, CD3 + T cell, and CD4 + T cell counts are associated with disease severity.

Tigecycline in the treatment of severe pneumonia caused by Chlamydia psittaci: A case report and literature review

Psittacosis is a zoonotic disease caused by Chlamydia psittaci. Systemic infections are mainly transmitted through the respiratory tract. The most common related disease is human atypical pneumonia, which is a rare pathogen of community-acquired pneumonia. Due to the difficulty of diagnosis, there have been few reports of C. psittaci pneumonia in the past. In recent years, with the widespread application of metagenomic next-generation sequencing (mNGS), the number of reported cases of C. psittaci has increased year by year. However, at present, most hospitals have little understanding of C. psittaci, especially for severe patients, and lack experience in diagnosis and treatment. Herein, we report the case of a 71-year-old woman with severe pneumonia that caused by C. psittaci. This patient was diagnosed through mNGS and was treated with tigecycline successfully. The level of IL-6 in the BALF was significantly increased. We discontinued tigecycline after mNGS of the blood was negative. In this review, we analyzed 53 cases to summarize the etiology, clinical manifestations, diagnosis and treatment strategies of severe C. psittaci pneumonia and hope to raise clinicians' awareness of this disease.

A Chlamydia psittaci Outbreak in Psittacine Birds in Sardinia, Italy

Chlamydia psittaci is an intracellular bacterium belonging to the Chlamydiaceae family. It is the ethiologic agent of psittacosis, an occupational zoonotic disease that mainly concerns people who work in close contact with birds that represent the main infection route for human transmission. In Italy, information about this disease is lacking. This study is the first case of avian chlamydiosis reported from a pet shop in Sardinia, Italy. Chlamydia psittaci detected in psittacine birds by molecular analysis, direct immunofluorescence test together with anatomo-pathological observed lesions, highlighted the importance of focusing the attention over this underestimated zoonosis in a "One Health" prospective.

Chlamydia psittaci in Faecal Samples of Feral Pigeons (Columba livia forma urbana) in Urban Areas of Lublin city, Poland

Pigeons are a typical host and natural reservoir of Chlamydia psittaci, the etiological agent of avian chlamydiosis, considered as a neglected zoonotic diseases. The aim of the study was to determine the prevalence of C. psittaci in faecal samples of feral pigeons (Columba livia forma urbana) as a potential source of infection related to the presence of synanthropic birds in urban areas. A total of 143 samples of dry and fresh faeces of feral pigeons, were collected in the city of Lublin (Poland), from April to September 2021. Molecular detection of C. psittaci was performed by nested-PCR and real-time PCR, confirmed by sequencing. Among the collected samples, 5 positive results were obtained in nested-PCR (3.5%), while in real-time PCR, the number of positive samples increased to 11 (7.7%). The positive samples showed 100% identity to the C. psittaci strain AMK (CP047319.1). C. psittaci was found in 7 out of 111 (6.3%) faecal samples collected in public places, and in 4 out of 32 (12.5%) samples from the nesting site (4.9% and 2.8% among a total of 143 samples, respectively). The infection was detected in both dry and fresh faeces (9.1% and 4.5%, respectively). The highest number of positive results was obtained in June—5 (3.5%). Feral pigeons occurring in urban areas are a natural reservoir of C. psittaci posing a potential risk of zoonotic infections. However, further studies on exposure to contaminated pigeon faeces in terms of occupational and non-occupational risk of chlamydiosis are needed.

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.