Psittacosis--a review of 135 cases

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

Validation of JRS atypical pneumonia score in patients with community-acquired Chlamydia psittaci pneumonia

INTRODUCTION

The Japanese Respiratory Society (JRS) atypical pneumonia score is a useful tool for the rapid presumptive diagnosis of atypical pneumonia. We investigated the clinical features of community-acquired pneumonia (CAP) due to Chlamydia psittaci and validated the JRS atypical pneumonia score in patients with C. psittaci CAP.

METHODS

This study was conducted at 30 institutions and assessed a total of 72 sporadic cases with C. psittaci CAP, 412 cases with Mycoplasma pneumoniae CAP, and 576 cases with Streptococcus pneumoniae CAP.

RESULTS

Sixty-two of 72 patients with C. psittaci CAP had a history of avian exposure. Among the six parameters of the JRS score, matching rates of four parameters were significantly lower in the C. psittaci CAP than the M. pneumoniae CAP in the following parameters: age <60 years, no or minor comorbid illness, stubborn or paroxysmal cough, and absence of chest adventitious sounds. The sensitivity of the diagnosis of atypical pneumonia in patients with C. psittaci CAP was significantly lower than the M. pneumoniae CAP (65.3% and 87.4%, p < 0.0001). When the diagnostic sensitivity was analyzed for different ages, the diagnostic sensitivities for the C. psittaci CAP were 90.5% for non-elderly patients and 30.0% for elderly patients.

CONCLUSIONS

The JRS atypical pneumonia score is a useful tool for distinguishing between C. psittaci CAP and bacterial CAP in patients aged <60 years, but not in patients aged ≥60 years. A history of avian exposure in middle-aged patients with normal white blood cell count may be suggestive of C. psittaci pneumonia.

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: A case of Chlamydia psittaci infection in an HIV patient

Chlamydia psittaci is the pathogen of psittacosis and infects a wide range of birds and even humans. Human infection occurs most commonly in those with a history of contact with birds or poultry. We describe a case of psittacosis in a human immunodeficiency virus infected patient in Zhejiang Province for the first time. C. psittaci infection was confirmed by nested polymerase chain reaction (PCR) and Real-Time PCR. Phylogenetic analysis revealed that the sequences from the patient's samples clustered with genotype A in the same branch. Our study highlights the possibility of diagnosing psittacosis in patients with a chronic disease such as HIV-infected patients, and should increase awareness and surveillance of psittacosis in China.

Psittacosis contagion in 1930: an old story in a new era of zoonotic disease

The SARS-CoV-2 pandemic has highlighted the importance of zoonotic diseases. Psittacosis, a human disease resulting from infection spill-over from Chlamydia psittaci-infected birds, is a lesser-known example of a zoonosis. Psittacosis was responsible for numerous outbreaks in the 1930s, characterised by significant human mortality and disruption to the global trade in parrots. This paper describes the epidemiological and clinical details of one family group impacted by the purchase of an infected, imported parrot. Findings are discussed in the context of a growing awareness of the health risks of global disease outbreaks, as well as social and economic impacts. Health information recorded for cases of psittacosis associated with the 1930 cluster was reviewed using contemporary knowledge of disease symptoms and epidemiology. Case details and autopsy reports were examined. Public health investigation deduced that the cluster of infections was chronologically and physically connected to the purchase and subsequent death of an imported parrot. Disease symptoms were consistent with C. psittaci infection. Epidemiological data supported the diagnoses and causes of death, despite the presenting symptoms sharing significant overlap with other common respiratory diseases. There is growing awareness of the risks of epidemiological bridges in transmitting animal diseases to humans. Historical cases are a strong reminder of the fundamental role of scientific and public health responses in the face of such contagion.

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.

A cluster of Psittacosis cases in Lishui, Zhejiang Province, China, in 2021

Introduction

Psittacosis, caused by Chlamydia psittaci, is widespread throughout the world. In humans, C. psittaci infection may lead to severe conditions and complications, including sepsis and multiple organ failure. We report a cluster of cases caused by C. psittaci in Zhejiang Province, 2021, which led to one death and three cases of hospitalization.

Methods

The cases were confirmed by nest-PCR, RT-PCR, and mNGS.

Results

The four cases were related and the sequences obtained from the samples were closely correlated with those from Taiwan.

Discussion

This study is the first to report on the case of death from psittacosis in Zhejiang Province, and our results help to assess the disease and recommend effective measures to prevent further spread of C. psittaci.

Persistent renal replacement requirement following fulminant psittacosis infection in pregnancy

Chlamydia psittaci is a zoonotic bacterial infection that most commonly causes mild flu-like symptoms in humans. However, in pregnancy, it can present as fulminant psittacosis associated with systemic illness, disseminated intravascular coagulation, renal and hepatic failure. We describe a case of a veterinary nurse in her 30s who presented at 32 weeks' gestation with rapidly progressive multiorgan failure, with positive, C. psittaci serology. Further history revealed that she had delivered a number of dead lambs in the preceding weeks to her illness, highlighting the importance of a thorough social history. C. psittaci should be suspected in the differential as a causative organism for severe pneumonia with multiorgan failure particularly in pregnant women with animal or bird contacts.

Atypical Pathogens in Adult Community-Acquired Pneumonia and Implications for Empiric Antibiotic Treatment: A Narrative Review

Atypical pathogens are intracellular bacteria causing community-acquired pneumonia (CAP) in a significant minority of patients. Legionella spp., Chlamydia pneumoniae and psittaci, Mycoplasma pneumoniae, and Coxiella burnetii are commonly included in this category. M. pneumoniae is present in 5-8% of CAP, being the second most frequent pathogen after Streptococcus pneumoniae. Legionella pneumophila is found in 3-5% of inpatients. Chlamydia spp. and Coxiella burnetii are present in less than 1% of patients. Legionella longbeachae is relatively frequent in New Zealand and Australia and might also be present in other parts of the world. Uncertainty remains on the prevalence of atypical pathogens, due to limitations in diagnostic means and methodological issues in epidemiological studies. Despite differences between CAP caused by typical and atypical pathogens, the clinical presentation alone does not allow accurate discrimination. Hence, antibiotics active against atypical pathogens (macrolides, tetracyclines and fluoroquinolones) should be included in the empiric antibiotic treatment of all patients with severe CAP. For patients with milder disease, evidence is lacking and recommendations differ between guidelines. Use of clinical prediction rules to identify patients most likely to be infected with atypical pathogens, and strategies of narrowing the antibiotic spectrum according to initial microbiologic investigations, should be the focus of future investigations.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

The Application Value of Metagenomic and Whole-Genome Capture Next-Generation Sequencing in the Diagnosis and Epidemiological Analysis of Psittacosis

Background

To evaluate the value of metagenomic next-generation sequencing (mNGS) for the early diagnosis of psittacosis, and to investigate its epidemiology by whole-genome capture.

Methods

Twenty-one bronchoalveolar lavage fluid (BALF) and blood samples of 16 psittacosis patients from multiple centers during August 2019 to September 2021 were analyzed retrospectively. mNGS with normal datasets (10 M 75-bp single-end reads after sequencing) and larger datasets (30 M 150-bp paired-end reads after sequencing) as well as quantitative real-time polymerase chain reaction (qPCR) were used to detect the pathogen. Also, whole-genome capture of Chlamydophila psittaci was applied to draw the phylogenetic tree.

Results

mNGS successfully detected the pathogen in all 16 cases (100%), while qPCR was positive only in 5 out of 10 cases (50%), indicating a significantly higher sensitivity of mNGS than qPCR (p &lt; 0.01). BALF-mNGS performed better than blood-mNGS (16/16 versus 3/5, p &lt; 0.05). In addition, larger datasets (the read counts have tripled, and the base number was 12-fold larger compared to clinical mNGS with a normal dataset) of mNGS showed significantly increased contents of human DNA (p &lt; 0.05) and decreased reads per million of the pathogen, suggesting no improvement. Whole-genome capture results of five samples (&gt;60% coverage and &gt;1 depth) were used to construct the phylogenetic tree.

Conclusion

Significant advantages of mNGS with normal datasets were demonstrated in early diagnosing psittacosis. It is the first study to use whole-genome capture to analyze C. psittaci epidemiological information.

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

Here, we aimed to retrospectively analyze the clinical characteristics of 27 patients with severe pneumonia caused by Chlamydia psittaci between January 2019 and April 2021 in southwest China. To this end, we collected data on the exposure history, clinical symptoms, laboratory examination, imaging characteristics, evolution, etiology, treatment, and outcomes to suggest a better diagnosis and prevention system. Our results showed that a metagenomic next-generation sequencing test could provide early diagnosis. All patients were sensitive to quinolones and tetracyclines, and the recovery rate was relatively high. Overall, all patients were in critical condition with moderate to severe acute respiratory distress syndrome and shock. In conclusion, early diagnosis of pneumonia caused by C. psittaci depends on effective molecular testing, and most patients recover after treatment.

A Rare Bird: Diagnosis of Psittacosis Meningitis by Clinical Metagenomic Next-Generation Sequencing

Psittacosis is a zoonotic infectious disease caused by the transmission of Chlamydia psittaci; it often presents as a pulmonary infection but rarely as disseminated disease. Because diagnoses of psittacosis are often underreported due to infrequent pathogen-specific testing, clinical metagenomic next-generation sequencing may be helpful to diagnose such an uncommon syndrome.

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.

Severe psittacosis progressing to suspected organizing pneumonia and the role of corticosteroids

Background

Psittacosis is a systemic disease usually with respiratory involvement, caused by the obligate intracellular bacterium Chlamydia psittaci. Exposure to birds, the main zoonotic reservoir, is a major risk factor for infection. The spectrum of disease is highly variable, ranging from subclinical infection to severe pneumonia requiring mechanical ventilation. There is limited data on psittacosis progressing to organizing pneumonia and management of such cases.

Case presentation

A 63-year-old man was referred to a rural hospital with 11 days of fevers to 39 °C, myalgia, lethargy and several days of dry cough. After initial treatment with benzylpenicillin and doxycycline for left lower pneumonia found on CXR, the patient deteriorated with extensive bilateral consolidation on chest CT requiring mechanical ventilation. Atypical pneumonia screening was negative, however, exposure to a sick bird prior to symptom onset triggered testing for C. psittaci which was positive. Doxycycline was recommenced with minimal benefit, and organizing pneumonia was later suspected. The patient slowly improved with a weaning course of corticosteroids started after 19 days and was discharged from hospital. He unfortunately was re-admitted and died several months later.

Conclusion

Severe pneumonia is a rare, but potentially life-threatening complication of psittacosis. We present a case of psittacosis which progressed to suspected organizing pneumonia despite appropriate antibiotics, and subsequent treatment with corticosteroids. This case suggests it may be useful to consider corticosteroids early in therapy for patients with severe psittacosis. Our paper underlines the need for further research to determine the best management of severe psittacosis to improve patient outcomes.

A case of chlamydia psittaci caused severe pneumonia and meningitis diagnosed by metagenome next-generation sequencing and clinical analysis: a case report and literature review

Background

Psittacosis, which is also known as parrot fever, is Chlamydia psittaci (C. psittaci) caused infectious disease. The clinical manifestations vary from asymptomatic infection to severe atypical pneumonia or even fatal meningitis. Early recognition of psittacosis is difficult because of its nonspecific clinical manifestations. Culture and gene probe techniques for C. psittaci are not available for routine clinical use, which makes the diagnosis difficult too. Although psittacosis has increasingly been recognized and reported in recent years, cure of severe pneumonia complicated with meningitis, with etiologic diagnosis aided by the use of metagenomic next-generation sequencing (mNGS), is still uncommon. So, it is necessary to report and review such potentially fatal case.

Case presentation

This report describes a 54-year-old woman with C. psittaci caused severe atypical pneumonia and meningitis. She presented with symptoms of fever, dry cough and dyspnea, accompanied by prominent headache. Her condition deteriorated rapidly to respiratory failure and lethargy under the treatment of empirical antibacterial agents, and was treated with invasive mechanical ventilation soon. She denied contact with birds, poultry or horses, but unbiased mNGS of both the bronchoalveolar lavage fluid (BALF) and the cerebrospinal fluid (CSF) identified sequence reads corresponding to C. psittaci infection, and there was no sequence read corresponding to other probable pathogens. Combined use of targeted antimicrobial agents of tetracyclines, macrolides and fluoroquinolones was carried out, and the patient’s condition improved and she was discharged home 28 days later. Her status returned close to premorbid condition on day 60 of follow-up.

Conclusions

When clinicians come across a patient with atypical pneumonia accompanied by symptoms of meningitis, psittacosis should be taken into consideration. mNGS is a promising detection method in such condition and is recommended.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06205-5.

Multi-organ failure with necrotic skin lesions due to infection with Chlamydia psittaci

Presented is a patient with dyspnea and painful ulcers finally resulting in multi-organ failure. A detailed history resulted in positive PCR testing for Chlamydia psittaci. We emphasize the importance of a definitive history in establishing the correct diagnosis. When clinicians observe dyspnea with multi-organ failure, they should be aware of psittacosis.

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.

Gestational psittacosis: A case report and literature review

Gestational psittacosis is a rare disease that is associated with significant maternal and fetal morbidity and mortality. Currently, there is no examination method which allows for a quick diagnosis. We report a case of gestational psittacosis that could not be diagnosed as psittacosis during treatment and resulted in maternal and fetal death despite intensive treatment. We also reviewed 23 cases of gestational psittacosis. Fetal and maternal mortality was 82.6% (19/23) and 8.7% (2/23), respectively. In pregnant women with high fever and flu-like symptoms, we should suspect Chlamydia psittaci infection if at least one of the following is present; contact with sheep, parrots, parakeets or goats; normal or moderately decreased leucocyte count, thrombocytopenia and hepatic and/or renal dysfunction; cough and/or lobe consolidation or infiltration on chest X-ray. Antibiotic therapy with macrolide prenatally, macrolide or tetracycline postnatally and termination of pregnancy should be considered.

Chlamydiae from Down Under: The Curious Cases of Chlamydial Infections in Australia

In Australia, the most researched and perhaps the most successful chlamydial species are the human pathogen Chlamydia trachomatis, animal pathogens Chlamydia pecorum and Chlamydia psittaci. C. trachomatis remains the leading cause of sexually transmitted infections in Australians and trachoma in Australian Indigenous populations. C. pecorum is globally recognised as the infamous koala and widespread livestock pathogen, whilst the avian C. psittaci is emerging as a horse pathogen posing zoonotic risks to humans. Certainly not innocuous, the human infections with Chlamydia pneumoniae seem to be less prevalent that other human chlamydial pathogens (namely C. trachomatis). Interestingly, the complete host range for C. pecorum and C. psittaci remains unknown, and infections by other chlamydial organisms in Australian domesticated and wildlife animals are understudied. Considering that chlamydial organisms can be encountered by either host at the human/animal interface, I review the most recent findings of chlamydial organisms infecting Australians, domesticated animals and native wildlife. Furthermore, I also provide commentary from leading Australian Chlamydia experts on challenges and future directions in the Chlamydia research field.

ARDS in Fulminant Ornithosis and Treatment with Extracorporeal Lung Assist

We report a 47-year-old male patient with fulminant ornithosis who developed severe respiratory failure leading to acute respiratory distress syndrome (ARDS) complicated by gastrointestinal, neurological and renal symptoms. ARDS was successfully treated by extracorporeal lung assist. As leukocytosis is typically absent in ornithosis, C-reactive protein, interleukin 6 and procalcitonin were used as infection parameters in order to monitor clinical development. The English-language literature on severe cases of ornithosis requiring respiratory support over the past 30 years is reviewed.

Disease burden of psittacosis in the Netherlands

Psittacosis (infection with Chlamydia psittaci) can have diverse presentations in humans, ranging from asymptomatic infection to severe systemic disease. Awareness of psittacosis and its presentations are low among clinicians and the general public. Therefore, underdiagnosis and thereby underestimation of the incidence and public health importance of psittacosis is very likely. We used the methodology developed for the Burden of communicable diseases in Europe toolkit of the European Centre for Disease Prevention and Control, to construct a model to estimate disease burden in disability-adjusted life years (DALYs) attributable to psittacosis. Using this model, we estimated the disease burden caused by psittacosis in the Netherlands to have been 222 DALY per year (95% CI 172-280) over the period 2012-2014. This is comparable with the amount of DALYs estimated to be due to rubella or shigellosis in the same period in the Netherlands. Our results highlight the public health importance of psittacosis and identify evidence gaps pertaining to the clinical presentations and prognosis of this disease.

Underdiagnosis of Chlamydia trachomatis and Chlamydia psittaci revealed by introduction of respiratory multiplex PCR assay with Chlamydiaceae family primers

We describe unanticipated detection of respiratory infection with Chlamydia trachomatis and Chlamydia psittaci after introduction of respiratory multiplex polymerase chain reaction assay that includes Chlamydiaceae family primers. We detected cases of pediatric C. trachomatis and of adult C. psittaci infection in patients with previously unrecognized risk factors. Directed testing for C. trachomatis and C. psittaci based on clinical features and risk factors alone is likely to miss the majority of infected cases.

Legionnaire's Disease: Cardiac Manifestations

Most cardiac infections with Legionella are secondary to bacteremias arising from a pulmonary focus. Other possible sites of origin are infected sternotomy wounds or equipment contaminated by Legionella spp. Legionella endocarditis is truly a "stealth" infection, with almost no hallmarks of bacterial endocarditis. The key step in making the diagnosis of Legionella endocarditis is for the physician to be aware of the clinical causes of culture-negative infective endocarditis and to include Legionella cardiac involvement in this differential. Many times the issue of endocarditis arises only on examination of resected valvular material.

An outbreak of psittacosis at a veterinary school demonstrating a novel source of infection

In November 2014, New South Wales Health was notified of a cluster of respiratory illness in a veterinary school. Active case finding identified another case at a local equine stud. All cases had exposure to the equine fetal membranes of Mare A. This tissue subsequently tested positive for Chlamydia psittaci using quantitative real-time polymerase chain reaction. We conducted a cohort study of the university and stud farm staff to determine risk factors for disease. Nine people were exposed to the fetal membranes of Mare A. Of these, five cases of psittacosis were identified. Two required hospital admission. Contact with birds was not associated with illness (RR = 0.5, 95% CI = 0.09-2.73). People who had direct contact with the abnormal fetal membranes were more likely to develop disease (RR = 11.77, 95% CI = 1.02-∞). The emergence of an association between horse exposure and C. psittaci infection has important implications for the prevention and control of psittacosis. Article summary line: Investigation of an outbreak of psittacosis in a rural veterinary school demonstrates novel source of infection for psittacosis through exposure to abnormal equine fetal membranes.

Atypical aetiology in patients hospitalised with community-acquired pneumonia is associated with age, gender and season; a data-analysis on four Dutch cohorts

BACKGROUND

Microorganisms causing community-acquired pneumonia (CAP) can be categorised into viral, typical and atypical (Legionella species, Coxiella burnetii, Mycoplasma pneumoniae, and Chlamydia species). Extensive microbiological testing to identify the causative microorganism is not standardly recommended, and empiric treatment does not always cover atypical pathogens. In order to optimize epidemiologic knowledge of CAP and to improve empiric antibiotic choice, we investigated whether atypical microorganisms are associated with a particular season or with the patient characteristics age, gender, or chronic obstructive pulmonary disease (COPD).

METHODS

A data-analysis was performed on databases from four prospective studies, which all included adult patients hospitalised with CAP in the Netherlands (N = 980). All studies performed extensive microbiological testing.

RESULTS

A main causative agent was identified in 565/980 (57.7 %) patients. Of these, 117 (20.7 %) were atypical microorganisms. This percentage was 40.4 % (57/141) during the non-respiratory season (week 20 to week 39, early May to early October), and 67.2 % (41/61) for patients under the age of 60 during this season. Factors that were associated with atypical causative agents were: CAP acquired in the non-respiratory season (odds ratio (OR) 4.3, 95 % CI 2.68-6.84), age <60 year (OR 2.9, 95 % CI 1.83-4.66), male gender (OR 1.7, 95 % CI 1.06-2.71) and absence of COPD (OR 0.2, 95 % CI 0.12-0.52).

CONCLUSIONS

Atypical causative agents in CAP are associated with respectively non-respiratory season, age <60 years, male gender and absence of COPD. Therefore, to maximise its yield, extensive microbiological testing should be considered in patients <60 years old who are admitted with CAP from early May to early October.

TRIAL REGISTRATION

NCT00471640 , NCT00170196 (numbers of original studies).

Multiple human-to-human transmission from a severe case of psittacosis, Sweden, January-February 2013

Proven transmission of Chlamydia psittaci between humans has been described on only one occasion previously. We describe an outbreak which occurred in Sweden in early 2013, where the epidemiological and serological investigation suggests that one patient, severely ill with psittacosis after exposure to wild bird droppings, transmitted the disease to ten others: Two family members, one hospital roommate and seven hospital caregivers. Three cases also provided respiratory samples that could be analysed by PCR. All the obtained C. psittaci sequences were indistinguishable and clustered within genotype A. The finding has implications for the management of severely ill patients with atypical pneumonia, because these patients may be more contagious than was previously thought. In order to prevent nosocomial person-to-person transmission of C. psittaci, stricter hygiene measures may need to be applied.

Clinical features of endemic community-acquired psittacosis

Following a large outbreak of community-acquired psittacosis in 2002 in residents of the Blue Mountains, New South Wales, Australia, we reviewed new cases in this area over a 7-year period from 2003 to 2009. Using the 2010 criteria from the Centers for Disease Control National Notifiable Diseases Surveillance System, 85 patients with possible psittacosis were identified, of which 48 were identified as definite or probable infection. Clinical features of these cases are summarized. In addition to Chlamydia-specific serology, specimens, where available, underwent nucleic acid testing for chlamydial DNA using real-time PCR. Chlamydophila psittaci DNA was detected in samples from 23 patients. Four of 18 specimens were culture positive. This is the first description of endemic psittacosis, and is characterized in this location by community-acquired psittacosis resulting from inadvertent exposure to birds. The disease is likely to be under-diagnosed, and may often be mistaken for gastroenteritis or meningitis given the frequency of non-respiratory symptoms, particularly without a history of contact with birds. Clinical characteristics of endemic and outbreak-associated cases were similar. The nature of exposure, risk factors and reasons for the occurrence of outbreaks of psittacosis require further investigation.

A new look at chronicChlamydiainfections and the role of the MHC/HLA in diseases of the CNS

Chlamydia has attracted increased attention as a possible cause of atheromatous plaques, cerebrovascular diseases, multiple sclerosis, Alzheimer’s disease and schizophrenia. The Chlamydia species are obligate intracellular parasites. The unique biphasic life cycle of Chlamydia permits the parasite to persist in cells for years. Acute Chlamydia infections can be recognized serologically in the peripheral blood through observation of rising antibody titers or molecularly using various PCR methods. However, the identification of chronic Chlamydia infection is hampered by many hurdles. This has initiated controversial discussions about the true involvement of Chlamydia, particularly in the CNS. The aspects of the discussion will be inspected as well as the vulnerability of the neuronal MHC to immune reactions.

Risk assessment and management of Chlamydia psittaci in poultry processing plants

Chlamydia psittaci causes respiratory disease in poultry and can be transmitted to humans. Historical outbreaks of psittacosis in poultry workers indicated the need for higher awareness and an efficient risk assessment and management. This group reviewed relevant previous research, practical guidelines, and European directives. Subsequently, basic suggestions were made on how to assess and manage the risk of psittacosis in poultry processing plants based on a classical four-step approach. Collective and personal protective measures as well as the role of occupational medicine are described. Despite the finding that exposure is found in every branch, abattoir workstations seem to be associated with the highest prevalence of psittacosis. Complete eradication is difficult to achieve. Ventilation, cleaning, hand hygiene, and personal protective equipment are the most important protective measures to limit and control exposure to C. psittaci. Adequate information, communication, and health surveillance belong to the responsibilities of the occupational physician. Future challenges lay in the rigorous reporting of infections in both poultry and poultry workers and in the development of an avian and human vaccine.

Chlamydophila psittaci zoonotic risk assessment in a chicken and turkey slaughterhouse

Chlamydophila psittaci causes respiratory disease in poultry and can be transmitted to humans. We conducted a C. psittaci zoonotic risk assessment study of a chicken and turkey slaughterhouse. Eighty-five percent of the slaughtered chicken flocks tested positive by PCR and culture. Genotype D was discovered. Fifty-seven percent of the slaughtered turkey flocks tested positive by PCR and culture. Genotype D was present. For the chicken slaughterhouse employees, 7.5% and 6% tested positive for C. psittaci by PCR and culture, respectively. In the turkey slaughterhouse, 87% and 61% of the employees tested positive by PCR and culture, respectively. All genotyped human samples contained genotype D. Using stationary bioaerosol monitoring by means of an MAS-100 ecosampler and ChlamyTrap collection medium, chlamydial DNA, and viable organisms were detected in both the chicken and turkey slaughterhouses. Positive air samples were most frequently found in the animal reception area and evisceration room. Zoonotic transmissions were very common, especially from processed turkeys. Accurate diagnostic monitoring and reporting of C. psittaci infections should be promoted in poultry workers.

Acute respiratory infections in a recently arrived traveler to your part of the world

Many acute infectious pulmonary diseases have incubation periods that are long enough for travelers to have symptoms after returning home to a health-care system that is not familiar with "foreign" infections. Respiratory infections have a relatively limited repertoire of clinical manifestations, so that there is often nothing characteristic enough about a specific infection to make the diagnosis obvious. Thus, the pathway to the diagnosis of infections that are not endemic in a region relies heavily on taking a thorough history of both itinerary and of specific exposures. One important caveat is that on occasion, the history of a recent trip creates an element of "tunnel vision" in the evaluating health-care provider. It is tempting to relate a person's problem to that recent trip; however, when evaluating recent returnees, it is always important to remember that the travel may have nothing to do with the patient's presentation. Recent travel may add diagnostic considerations to the list of possibilities, but an astute clinician must not disregard the possibility that the patient's illness has nothing to do with the recent trip.

Development of an internally controlled real-time PCR assay for detection of Chlamydophila psittaci in the LightCycler 2.0 system

A real-time PCR assay with a DNA purification and inhibition control (internal control; IC) was developed to detect Chlamydophila psittaci DNA in human clinical samples. Novel C. psittaci-specific primers targeting the ompA gene were developed. The IC DNA contained the same primer-binding sites and had the same length and nucleotide content as the C. psittaci DNA amplicon, but had a shuffled probe-binding region. The lower limit of detection was 80 target copies/PCR, corresponding to 6,250 copies/mL in a clinical sample. Specificity was tested using reference strains of 30 bacterial species. No amplification was observed from any of these samples. Respiratory samples from eight patients were positive with this PCR. Six of these patients were confirmed as positive for C. psittaci with serological testing. Two patients had increasing antibody titres, but did not fulfil criteria proposed previously for serologically proven Chlamydia spp. infection. The real-time PCR described in this paper is a sensitive, specific and rapid method to detect C. psittaci DNA in human clinical respiratory samples.

An outbreak of psittacosis due to Chlamydophila psittaci genotype A in a veterinary teaching hospital

An outbreak of psittacosis in a veterinary teaching hospital was recognized in December 2004. Outbreak management was instituted to evaluate the extent of the outbreak and to determine the avian source. Real-time PCR, serologic testing and sequencing of the ompA gene of Chlamydophila psittaci were performed. Sputum samples from patients, throat-swab samples from exposed students and staff, and faecal specimens from parrots and pigeons were tested. In this outbreak, 34 % (10/29) of the tested individuals were infected. The clinical features of the infection ranged from none to sepsis with multi-organ failure requiring intensive-care-unit admission. C. psittaci genotype A was identified as the outbreak strain. Parrots, recently exposed to a group of cockatiels coming from outside the teaching facility, which were used in a practical class, appeared to be the source of the outbreak. One of the tested pigeons harboured an unrelated C. psittaci genotype B strain. The microbiological diagnosis by real-time PCR on clinical specimens allowed for rapid outbreak management; subsequent genotyping of the isolates identified the avian source. Recommendations are made to reduce the incidence and extent of future outbreaks.

Therapeutic approaches toChlamydiainfections

Chlamydia trachomatis ocular and urogenital infections represent major public health problems, whereas Chlamydophila pneumoniae is a common aetiological agent of community-acquired pneumonia. The obligate intracellular lifestyle of these established pathogens poses challenges to both their diagnosis and treatment. Tetracyclines, macrolides and quinolones remain the antimicrobials of choice for the treatment of infections due to Chlamydiaceae.

Infection by Chlamydophilia avium in an elderly couple working in a pet shop

Psittacosis infection is usually reported in adults aged around 30 to 60 years. We report here two cases of psittacosis in an elderly couple (76 and 77 years old) who jointly ran a pet shop. Psittacosis was diagnosed from a history of exposure to birds and from serological testing for Chlamydophilia avium.

Probable psittacosis outbreak linked to wild birds

Residence in the upper Blue Mountains, age of 50–64 years, direct contact with wild birds, and lawn mowing without a grass catcher were associated with psittacosis.

In autumn 2002, an outbreak of probable psittacosis occurred among residents of the Blue Mountains district, Australia. We conducted a case-control study to determine independent risk factors for psittacosis by comparing exposures between hospitalized patients and other residents selected randomly from the telephone directory. Of the 59 case-patients with laboratory results supportive of psittacosis, 48 participated in a case-control study with 310 controls. Independent risk factors were residence in the upper Blue Mountains (odds ratio [OR] = 15.2, 95% confidence interval [CI] 5.6–41.7), age of 50–64 years (OR = 3.9, 95% CI 1.5–10.5), direct contact with wild birds (OR = 7.4, 95% CI 2.5–22), and mowing lawns without a grass catcher (OR = 3.2, 95% CI 1.3–8.0). Protective equipment is recommended for residents in areas frequented by free-ranging birds if contact with birds and their droppings is likely when performing outdoor activities such as lawn mowing.