An unusual presentation of a case of human psittacosis

Serum C-reactive protein to albumin ratio as a potential risk indicator of pneumonia caused by Chlamydia psittaci: a multicenter retrospective study

Introduction

The aim of the study was to describe psittacosis pneumonia and to assess the predictive value of the C-reactive protein/albumin ratio in psittacosis pneumonia for severity.

Methods

Data on psittacosis pneumonia cases diagnosed using metagenomic sequencing were collected from three hospitals in Shanghai, China from Oct. 2019 to Oct. 2022. Serum levels of C-reactive protein and albumin were measured and the C-reactive protein to albumin ratio (CAR) was calculated. Spearman's correlation analysis, ordered logistic regression analysis, and receiver operating characteristic curve analysis were conducted to examine the correlation and predictive ability of the three indicators on the severity of the disease.

Results

A total of 27 patients with psittacosis pneumonia were enrolled, with an average age of 62 years and 70.4% being male. 44.4% of patients had a clear history of contact with poultry or birds. The predominant symptom was fever (100%). Patients treated in the respiratory intensive care unit (RICU) had a higher likelihood of experiencing wheezing (88.9% versus 33.3%, P=0.013) and chest tightness (88.9% vs. 33.3%, P=0.013) than those in the general ward (Non-RICU). The proportion of patients with pleural effusion was significantly higher in the RICU compared to the Non-RICU (88.9% vs. 38.9%, P=0.019). The RICU group had a significantly higher CAR than the Non-RICU group (9.41 vs. 4.05, P=0.017). This result was accompanied by higher intubation and ventilator support (33.3% vs. 0.0%, P=0.029), higher PCT and CRP levels and lower albumin and PaCO2 levels in the RICU than in the Non-RICU. Logistic regression analysis indicated that CAR (OR 1.49; 95% CI 1.07-2.06, P=0.017) was risk factor for prolonged hospitalization (> 14 days).

Discussion

Elevated serum CAR levels were found to be associated with a greater risk of severe psittacosis pneumonia. Consequently, it may serve as an uncomplicated and useful diagnostic tool for clinicians to promptly and precisely ascertain the severity of psittacosis pneumonia, ultimately aiding them in devising the most optimal therapeutic plan.

Omadacycline for the Treatment of Severe Chlamydia psittaci Pneumonia Complicated with Guillain-Barre Syndrome

Background

Chlamydia psittaci (C. psittaci) is a pathogen that is seldom implicated in community-acquired pneumonia and is rarely linked to severe pneumonia. Reports of severe C. psittaci pneumonia accompanied by Guillain-Barre syndrome (GBS) are scarce. Tetracyclines are the preferred therapeutic approach for psittacosis. Omadacycline, a novel tetracycline, demonstrates strong antibacterial efficacy against typical bacteria and atypical pathogens, including C. psittaci. However, its application in the treatment of psittacosis pneumonia remains constrained.

Case Presentation

A 77-year-old female patient was admitted to the hospital presenting with symptoms of fever, low back pain, and headache. The diagnosis of C. psittaci was established through the utilization of metagenomic next-generation sequencing (mNGS). Initial administration of moxifloxacin, meropenem, piperacillin-tazobactam, and doxycycline proved to be ineffective. Subsequent omadacycline leaded to the successful resolution of fever and dyspnea. However, after the endotracheal tube was removed, the patient experienced a rapid decline in symmetrical limb strength, leading to a diagnosis of GBS based on clinical manifestations, cerebrospinal fluid analysis, and electromyography. Following a 5-day course of immunoglobulin therapy and nutritional nerve treatment, the patient's condition ameliorated, culminating in an uncomplicated discharge.

Conclusion

This case provides evidence supporting the potential use of omadacycline as a therapeutic option for the treatment of severe C. psittaci pneumonia. The utilization of mNGS technology is of paramount importance in the prompt identification of uncommon pathogens, including C. psittaci. Nevertheless, the occurrence of GBS should be taken into consideration when C. psittaci pneumonia is accompanied by symmetrical limb weakness. These findings have important implications for the diagnosis, treatment, and management of 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.

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.

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.

Chlamydia psittaci Induces Autophagy in Human Bronchial Epithelial Cells via PERK and IRE1α, but Not ATF6 Pathway

Chlamydia psittaci is an important pathogen that causes chronic and atypical pneumonia in humans. Autophagy and the unfolded protein response (UPR) are important mechanisms for regulating the growth of infectious parasitic pathogens in living cells. Here, we explored whether C. psittaci infection induced autophagy via the UPR and the effect of these cellular responses on the survival and replication of C. psittaci in human bronchial epithelial cells (HBEs). Not only were the numbers of autophagosomes and the expression of LC3-II and Beclin1 increased following C. psittaci infection of HBEs, but also the expression of p62 (also called sequestosome-1) was downregulated. Moreover, after C. psittaci infection, the UPR and UPR sensors PERK/eIF2α and IRE1α/XBP1 were activated, but not the ATF6 pathway. When either Bip siRNA was used to block normal initiation of the UPR, or activation of the PERK and IER1α pathways was blocked with specific inhibitors GSK2606414 and 4μ8C, the level of autophagy caused by C. psittaci infection was significantly inhibited. Furthermore, blocking activation of the UPR and associated pathways significantly reduced the number of C. psittaci inclusions. Our research suggests that the UPR, via the PERK and IRE1α, but not ATF6 signaling pathways, regulates HBE-cell autophagy induced by C. psittaci infection and the replication of C. psittaci.

Sixteen cases of severe pneumonia caused by Chlamydia psittaci in South China investigated via metagenomic next-generation sequencing

Introduction. Chlamydia psittaci is an important cause of community-acquired pneumonia (CAP). The spectrum of CAP due to Chlamydia psittaci ranges from mild, self-limited to acute respiratory failure and the early identification of this disease can be challenging. Metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid has the potential to improve the pathogen identification in severe CAP.Hypothesis/Gap Statement. Metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid has the potential to rapidly identify pathogens in severe CAP. The early identification and appropriate use of antibiotics can improve the prognosis of severe CAP caused by Chlamydia psittaci.Aim. The aim of the study is to describe the clinical spectrum of severe psittacosis pneumonia to provide a better understanding of this disease and to demonstrate that mNGS is an effective method for pathogen detection.Methodology. Retrospective case analysis from November 2019 to November 2020 was performed. Sixteen cases of severe psittacosis pneumonia were diagnosed through mNGS. Clinical features, laboratory findings, imaging features, treatment and outcome were summarized.Results. Frequent symptoms included fever (16/16, 100%), dyspnoea (16/16, 100%), cough (12/16, 75%), sputum (11/16, 69%) and headache (9/16, 56%). The median leukocytosis was within the normal range, while C-reactive proteins, CK, LDH, AST, D-Dimer were significantly elevated. The feature of computed tomography included ground-glass opacity with consolidation and multiple lobar distributions. The total number of sequences of Chlamydia psittaci identified from bronchoalveolar lavage by mNGS varied from 58 to 57115. Five patients underwent noninvasive mechanical ventilation, four patients underwent high flow humidified oxygen therapy and one patient underwent invasive mechanical ventilation. Two patients had septic shock needing vasoactive medications. All of the sixteen patients experienced full recoveries.Conclusion. The symptoms of severe CAP caused by Chlamydia psittaci were not typical while laboratory results may have some clues. The mNGS technology can early detect of psittacosis, reduce unnecessary use of antibiotics and short the course of the disease.

Application of metagenomic next-generation sequencing in the diagnosis of severe pneumonia caused by Chlamydia psittaci

Purpose

Psittacosis is a zoonotic infectious disease caused by the transmission of the bacterium Chlamydia psittaci (C. psittaci) from birds to humans. Infections in humans mainly present as community-acquired pneumonia (CAP). However, most cases are treated without diagnostic testing, and the importance of Chlamydia psittaci infection as a cause of CAP is therefore unclear. Diagnostic tools, including culture, serologic test, and PCR-based methods, are available but prone to false negative results. Metagenomic next-generation sequencing (mNGS) has been increasingly used in the diagnosis of infectious diseases, particularly when conventional diagnostic approaches have limitation.

Detection of nucleic acid sequence of C. psittaci in respiratory tract samples by metagenomic next-generation sequencing (mNGS) is effective for early diagnosis of severe C. psittaci pneumonia. Timely treatment based on tetracycline can reduce unnecessary use of antibiotics and improve prognosis of patients with severe C. psittaci pneumonia.

Methods

Clinical data of thirteen patients with severe C. psittaci pneumonia diagnosed by mNGS were collected. Clinical manifestations, treatment and prognosis of patients were summarized.

Results

The typical symptoms of pneumonia caused by C. psittaci include fever, headache, myalgia, cough, and dyspnea. In the current study, all patients met the criteria for severe C. psittaci pneumonia and received mechanical ventilation, including noninvasive mechanical ventilation (five/thirteen) and invasive mechanical ventilation (eight/thirteen). The findings showed that patients with C. psittaci pneumonia presented with normal or slightly increased leucocytes and procalcitonin, and high C-reactive protein levels. Computed tomography manifestations included consolidation of lung parenchyma, with air bronchogram and pleural effusion in some patients. mNGS analysis results were obtained within 48–72 h. Eleven patients fully recovered after targeted treatment, however, two patients died from secondary multidrug-resistant Pseudomonas aeruginosa infection.

Conclusions

The findings of the current study show that mNGS is effective in diagnosis of C. psittaci pneumonia, and has significant diagnosis value in patients with severe infection. Patients responds well to the timely use of appropriate antibiotics.

Characteristics of Chlamydia suis Ocular Infection in Pigs

Chlamydia (C.) suis can often be isolated from conjunctival swab specimens from pigs with conjunctivitis or keratoconjunctivitis. In the field, it is assumed to be a multifactorial disease triggered by immunosuppressing factors. This is the first experimental study to provoke clinical signs of conjunctivitis in pigs after C. suis primary mono-infection. Five six-week-old male piglets, free of ocular chlamydia shedding and seronegative for Chlamydia, were conjunctivally infected with the C. suis-type strain S45 (1 × 10⁹ inclusion forming units), while four piglets served as negative controls. The infection group developed clinical signs of conjunctivitis with a peak in the first week post-infection. Immunohistochemical evaluation revealed the presence of Chlamydia not only in the conjunctival epithelium, but also in the enlarged lacrimal glands, lungs, and intestine. No circulating antibodies could be detected during the whole study period of three weeks, although three different test systems were applied as follows: the complement fixation test, MOMP-based Chlamydiaceae ELISA, and PmpC-based C. suis ELISA. Meanwhile, high numbers of IFN-γ-producing lymphocytes within PBMC were seen after C. suis re-stimulation 14 days post-infection. Hence, these data suggest that entry via the eye may not elicit immunological responses comparable to other routes of chlamydial infections.

A comprehensive review on avian chlamydiosis: a neglected zoonotic disease

Avian chlamydiosis is one of the important neglected diseases with critical zoonotic potential. Chlamydia psittaci, the causative agent, affects most categories of birds, livestock, companion animals, and humans. It has many obscured characters and epidemiological dimensions, which makes it unique among other bacterial agents. Recent reports on transmission from equine to humans alarmed the public health authorities, and it necessitates the importance of routine screening of this infectious disease. High prevalence of spill-over infection in equines was associated with reproductive losses. Newer avian chlamydial species are being reported in the recent years. It is a potential biological warfare agent and the disease is an occupational hazard mainly to custom officers handling exotic birds. Prevalence of the disease in wild birds, pet birds, and poultry causes economic losses to the poultry industry and the pet bird trade. Interestingly, there are speculations on the ‘legal’ and ‘illegal’ bird trade that may be the global source of some of the most virulent strains of this pathogen. The mortality rate generally ranges from 5 to 40% in untreated cases, but it can sometimes be higher in co-infection. The intracellular lifestyle of this pathogen makes the diagnosis more complicated and there is also lack of accurate diagnostics. Resistance to antibiotics is reported only in some pathogens of the Chlamydiaceae family, but routine screening may assess the actual situation in all pathogens. Due to the diverse nature of the pathogen, the organism necessitates the One Health partnerships to have complete understanding. The present review focuses on the zoonotic aspects of avian chlamydiosis with its new insights into the pathogenesis, transmission, treatment, prevention, and control strategies. The review also briefs on the basic understandings and complex epidemiology of avian chlamydiosis, highlighting the need for research on emerging one health perspectives.

Animal sources for zoonotic transmission of psittacosis: a systematic review

Background

Human psittacosis, caused by Chlamydia (C.) psittaci, is likely underdiagnosed and underreported, since tests for C. psittaci are often not included in routine microbiological diagnostics. Source tracing traditionally focuses on psittacine pet birds, but recently other animal species have been gaining more attention as possible sources for human psittacosis. This review aims to provide an overview of all suspected animal sources of human psittacosis cases reported in the international literature. In addition, for each animal species the strength of evidence for zoonotic transmission was estimated.

Methods

A systematic literature search was conducted using four databases (Pubmed, Embase, Scopus and Proquest). Articles were included when there was mention of at least one human case of psittacosis and a possible animal source. Investigators independently extracted data from the included articles and estimated strength of evidence for zoonotic transmission, based on a self-developed scoring system taking into account number of human cases, epidemiological evidence and laboratory test results in human, animals, and the environment.

Results

Eighty articles were included, which provided information on 136 different situations of possible zoonotic transmission. The maximum score for zoonotic transmission was highest for turkeys, followed by ducks, owls, and the category ‘other poultry’. Articles reporting about zoonotic transmission from unspecified birds, psittaciformes and columbiformes provided a relatively low strength of evidence. A genotypical match between human and animal samples was reported twenty-eight times, including transmission from chickens, turkeys, guinea fowl, peafowl, pigeons, ducks, geese, songbirds, parrot-like birds and owls.

Conclusions

Strong evidence exists for zoonotic transmission from turkeys, chickens and ducks, in addition to the more traditionally reported parrot-like animal sources. Based on our scoring system, the evidence was generally stronger for poultry than for parrot-like birds. Psittaciformes should not be disregarded as an important source of human psittacosis, still clinicians and public health officials should include poultry and birds species other than parrots in medical history and source tracing.

Human psittacosis: a review with emphasis on surveillance in Belgium

Chlamydia psittaci causes psittacosis in humans, mainly in persons in contact with birds in either the setting of occupational or companion bird exposure. Infection is associated with a range of clinical manifestations from asymptomatic infection to severe atypical pneumonia and systemic disease. This paper reviews new knowledge on psittacosis, its legal and regulatory aspects and presents epidemiological data on psittacosis in Belgium. In Belgium, the number of reported positive laboratory results increased slowly since 2010, and in 2017, the number almost doubled compared to the two previous years. The number of psittacosis cases in Belgium, as in other countries, is probably highly underestimated, because of underdiagnoses and underreporting. Over the 3-year period, the mandatory notification system registered 24% only of all reported positive laboratory result. Therefore, increased awareness among general and occupational physicians, clinicians and the public is needed. Policies aimed at reducing psittacosis disease burden are justified, nevertheless national health authorities should provide more legal and financial support to implement more adequate C. psittaci diagnostic tools.