Clinical Symptoms and Outcomes of Severe Pneumonia Caused by Chlamydia psittaci in Southwest China

Chlamydia psittaci Pneumonia: Diagnosis, Treatment, and Challenges in the Context of COVID-19

BACKGROUND Rapid diagnosis is critical for effective treatment of severe pneumonia during the COVID-19 pandemic. Chlamydia psittaci, an atypical community-acquired pathogen, typically exhibits nonspecific clinical signs and requires stringent conditions for microbiological culture, complicating its identification. Metagenomic next-generation sequencing (mNGS), which involves shotgun sequencing of DNA or RNA from clinical samples, is a key technology in clinical settings. Although mNGS technology identifies nucleic acids, it should not be directly equated with the presence of pathogenic microorganisms. Nonetheless, it shows promise as a principal method for detecting atypical pathogens in severe infectious diseases in the future. CASE REPORT We present a case of severe community-acquired Chlamydia psittaci pneumonia, highlighting the ongoing mutations and frequent spread of COVID-19. The patient's severe pulmonary infection rapidly advanced, resulting in multiple organ failure, necessitating extracorporeal membrane oxygenation (ECMO) support. Despite initial inconclusive routine laboratory tests, diagnosis of Chlamydia psittaci pneumonia was confirmed through mNGS. Antibiotic treatment and multi-organ functional support were administered, leading to the patient's successful recovery and hospital discharge. CONCLUSIONS Diagnosing severe pneumonia caused by atypical pathogens amid the COVID-19 pandemic presents significant challenges. Initiating ECMO support without effective infection control poses considerable risks, such as increasing risk of catheter-related infections and antimicrobial treatment failure. In the case presented, mNGS proved instrumental in screening for atypical pathogens in critical infectious diseases. Application of multi-organ function support in reversible conditions affords clinicians time for pathogen identification and treatment, offering novel approaches for diagnosing and treating severe pneumonia induced by unconventional pathogens during epidemic outbreaks.

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.

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.

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.

Diagnosis and Prognosis Evaluation of Severe Pneumonia by Lung Ultrasound Score Combined with Serum Inflammatory Markers

Introduction

To analyze the significance of lung ultrasound score (LUS) combined with serum inflammatory indexes in different severities of severe pneumonia and its clinical value on prognosis.

Methods

100 patients with severe pneumonia treated in the Gansu Provincial Hospital from June 2017 to June 2021 were selected as the research objects. According to the acute physiology and chronic health (APACHE II) score, they were divided into a low-risk group (28 cases), a medium-risk group (39 cases) and a high-risk group (33 cases). The general clinical data of the patients (age, gender, smoking history, and underlying diseases) were collected, the lung ultrasound score (LUS) of the patients was measured, and the serum inflammatory indicators (IL-6, IL-10, TNF-α, CRP and NLR) levels; Pearson correlation analysis to evaluate the correlation between LUS score, serum inflammatory index levels and disease severity; receiver operating characteristic (ROC) curve analysis to evaluate the prognostic value of the combined diagnosis of LUS score and serum inflammatory index for the severity of severe pneumonia.

Results

With the increase in the severity of severe pneumonia, the LUS score and the level of inflammation in the body continued to increase, and LUS combined with serum inflammatory indexes could distinguish the severity of low-risk, medium-risk and high-risk severe pneumonia and had high diagnostic value. In addition, the combined diagnosis of LUS and serum inflammatory markers is also closely related to the prognosis of patients with severe pneumonia, which can distinguish the prognosis.

Conclusion

LUS combined with serum inflammatory indicators (IL-6, IL-10, TNF-α, CRP and NLR) can differentiate the severity and prognosis of severe pneumonia, which may be a new direction for diagnosing severe pneumonia and guide early clinical intervention.

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.

Clinical features and outcome of eight patients with Chlamydia psittaci pneumonia diagnosed by targeted next generation sequencing

INTRODUCTION

The clinical symptoms of Chlamydia psittaci pneumonia are still poorly understood. This study was designed to summarize the clinical features and outcome of eight C. psittaci pneumonia patients diagnosed by targeted next generation sequencing (tNGS).

METHODS

We included eight C. psittaci pneumonia patients admitted to our hospital from January 2021 to July 2022. The tNGS was performed to the samples collected from bronchoalveolar lavage fluid of each patient. Their clinical data were analysed, including baseline features, clinical symptoms, chest radiographic findings and laboratory examinations.

RESULTS

The tNGS sequence number for C. psittaci was in a range of 10 to 1722. The radiographic characteristics were mainly featured by patchy consolidation shadows, ground-glass density shadows, air bronchogram and slight pleural effusion. Within 1-3 days after hospitalization, most patients showed increased neutrophil ratio, C-reactive protein and erythrocyte sedimentation rate, and decreased lymphocyte count, total protein, albumin and prealbumin. Some patients showed increased glutamic-pyruvic transaminase, glutamic-oxaloacetic transaminase and lactate dehydrogenase levels. Three critically ill patients showed increased creatine kinase, creatine kinase isoenzyme and high-sensitivity troponin T (hs-TnT) levels.

CONCLUSIONS

A poultry or bird contact history, typical flu-like symptoms, patchy consolidation, ground-glass density shadow and air bronchogram may contribute to the diagnosis and treatment of C. psittaci pneumonia. Increase in creatine kinase, creatine kinase isoenzyme and hs-TnT may indicate a severe condition. Moxifloxacin and minocycline were effective in the management of C. psittaci pneumonia.

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.

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.

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.

Clinical Features, Treatment, and Outcome of Psittacosis Pneumonia: A Multicenter Study

Background

We aimed to describe psittacosis pneumonia and risk factors for developing severe pneumonia in this multicenter clinical study.

Methods

We collected the data of psittacosis pneumonia cases diagnosed with metagenomic next-generation sequencing (mNGS) assay from April 2018 to April 2022 in 15 tertiary hospitals in China.

Results

A total of 122 patients were enrolled; 50.0% had a definite history of bird exposure. In 81.2% of cases, onset happened in autumn or winter. The common symptoms were fever (99.2%), cough (63.1%), fatigue (52.5%), shortness of breath (50.0%), chills (37.7%), central nervous system symptoms (36.9%), myalgia (29.5%), and gastrointestinal tract symptoms (15.6%). Laboratory tests showed that >70% of cases had elevated C-reactive protein, procalcitonin, erythrocyte sedimentation rate, D-dimer, lactate dehydrogenase, and aspartate aminotransferase, and >50% had hyponatremia and hypoproteinemia. The most common imaging finding was consolidation (71.3%), and 42.6% of cases met the criteria for severe pneumonia. Age >65 years and male sex were the risk factors for severe pneumonia. The effective proportion of patients treated with tetracyclines was higher than that of fluoroquinolones (66/69 [95.7%] vs 18/58 [31.0%]; P < .001), and the median defervescence time was shorter. After medication adjustment when the diagnosis was clarified, 119 of 122 (97.5%) patients were finally cured and the other 3 (2.5%) died.

Conclusions

Psittacosis pneumonia has a high rate of severe disease. Proven diagnosis could be rapidly confirmed by mNGS. Tetracycline therapy had a rapid effect and a high cure rate.

Chlamydia psittaci pneumonia: a clinical analysis of 12 patients

Background

We conducted a retrospective analysis to explore the clinical characteristics, laboratory examination, imaging features, treatment outcomes, and prognosis of the Chlamydia psittaci (C. psittaci) pneumonia, aiming to improve early diagnosis and treatment.

Methods

The clinical data of 12 patients with C. psittaci pneumonia diagnosed by metagenomic next-generation sequencing (mNGS) in our hospital were retrospectively analyzed. These data included baseline information, epidemiological history, clinical symptoms and signs, laboratory and chest computed tomography (CT) examination findings, treatment schemes, and prognosis.

Results

The average age of the 12 patients was 58.25±13.27 years, and there were 7 (58.3%) males and 5 (41.7%) females in this cohort. Five patients had clear exposure to poultry or birds. The main clinical manifestations included fever (12/12, 100.0%), cough (12/12, 100.0%), expectoration (10/12, 83.3%), and dyspnea (10/12, 83.3%). Laboratory examination showed marked elevation of the total white blood cell (WBC) count, neutrophil (NEUT) count, C-reactive protein (CRP), procalcitonin (PCT), D-dimer, aspartate aminotransferase (AST), alanine aminotransferase (ALT), serum creatinine, and creatine kinase (CK) levels; as well as decreased hemoglobin (HGB), blood platelet (PLT), and albumin (ALB) levels. Arterial blood gas analysis showed that the average value of the oxygenation index (PO₂/FiO₂) was 290.9±83.1, which was less than 300 in 6 cases (50.0%). The main chest CT features were patchy or consolidation in the bilateral or unilateral lungs, and the boundary was not clear but showed a bronchial inflation sign. Also, some of the cases were accompanied by pleural effusion. Once the etiology was obtained, the patients were quickly treated with doxycycline combined with other antibiotics. All 12 patients improved and were discharged from the hospital. However, two severe patients were admitted to the intensive care unit (ICU) and received ventilation and monitoring treatment. There were no deaths.

Conclusions

C. psittaci pneumonia is an atypical community-acquired pneumonia (CAP) caused by C. psittaci infection, with its own laboratory and imaging characteristics. In this study, diagnosis was established based on the application of mNGS owing to the absence of easily available conventional pathogenic evidence. In addition, an aggressive and precise treatment strategy can help achieve a favorable prognosis for patients.

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.

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.