A novel variant of Chlamydia psittaci causing human psittacosis in China

From January 2022 to November 2022, sporadic psittacosis occurred in Lishui city, China. The patients were presented with fever, cough, and pulmonary infiltration. Their clinical symptoms were not relieved after receiving cephalosporin, penicillin, beta-lactamase inhibitors, and quinolones. Metagenomic next-generation sequencing of bronchoalveolar lavage fluid samples from the patients revealed Chlamydia psittaci infection. Then, three C. psittaci strains were isolated from the patients. Their whole genome sequences (WGSs) were obtained, and a core genome multilocus sequence typing (cgMLST) method was developed to study the population structure of C. psittaci. Using the constructed cgMLST method, 72 WGSs were divided into four related groups and ten sub-clusters. The Lishui strains formed a unique population of C. psittaci, which might represent a new variant of C. psittaci. In vitro antimicrobial susceptibility testing suggested that the Lishui strains were sensitive to tetracycline, macrolides, quinolones, and no drug-resistance was observed.

Prevalence and genotypes of Chlamydia psittaci in pet birds of Hong Kong

Psittacosis, or parrot fever, is a zoonotic disease caused by Chlamydia species associated with birds. One of the causative agents of the disease is Chlamydia psittaci, which is commonly carried by psittacine and other bird species, can be highly pathogenic and virulent to humans. In Hong Kong, a city with high population density, psittacosis is a notifiable disease with over 60% of cases in the last decade resulting in hospitalization. However, the sources of transmission of C. psittaci and its prevalence in pet birds in Hong Kong are currently unknown. To evaluate the risks of psittacosis transmission through pet birds, we tested the presence of C. psittaci and determined its genotypes in samples obtained from 516 captive birds from households, pet shops, and a veterinary hospital in Hong Kong. Results revealed that five samples (0.97%), collected from budgerigars and cockatiels, were C. psittaci-positive, while four (80%) of them were obtained from pet shops. Our phylogenetic analysis revealed that all identified strains belonged to Genotype A and showed high similarity to other sequences of this genotype obtained from various geographical locations and host species, including mammals. Our findings provide evidence for the presence of Chlamydia psittaci and shed light on its sources in captive birds in Hong Kong. They highlight the potential zoonotic risks associated with this pathogen, which can affect both humans and wild birds.

Prevalence and genotypes of Chlamydia psittaci in birds and related workers in three cities of China

Chlamydia psittaci-a zoonotic pathogen in birds-may be transmitted to humans, causing severe respiratory disease. Individuals working in or living near poultry farms are highly susceptible to C. psittaci infection. In this study, we assessed the prevalence and genotypes of C. psittaci in poultries and humans in three cities of China by collecting fecal samples from different poultry species and throat swab samples and serum samples from workers in poultry farms and zoos. These samples were screened by real-time fluorescence quantitative PCR (qPCR) targeting C. psittaci ompA. The positive samples were subjected to PCR amplification and sequencing of ompA. The strains detected in the samples were genotyped on the basis of the phylogenetic analysis of ompA sequences. In total, 3.13% (40/1278) poultry fecal samples were positive in the qPCR assay, whereas 3.82% (6/157) of throat swab samples and 42.59% (46/108) of serum samples from the workers were positive in the qPCR and indirect fluorescent antibody assays, respectively. The strains detected in the 32 poultry samples and 6 human samples were genotyped as type A, indicating that the workers were infected with C. psittaci that originated in poultry birds in farms. Additionally, eight peacocks showed strains with the genotype CPX0308, which was identified in China for the first time. Elucidating the distribution of C. psittaci in animals and poultry-related workers may provide valuable insights for reducing the risk of C. psittaci infection within a population.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Chlamydia psittaci-related pleuro-myocarditis

Chlamydia psittaci ‒ related community-acquired pneumonia associated to acute myocarditis was diagnosed in a young man with no medical history, and a professional exposition to birds. The diagnosis was confirmed with positive specific polymerase chain reaction in bronchoalveolar lavage. The patient was treated with spiramycin for two weeks with anti-inflammatory treatment for myocarditis for three months. Clinical and biological improvement was rapidly observed followed by normalization of electrocardiogram and chest CT scan. No relapse was reported for over a two-year follow-up.

Application of environmental sampling to investigate a case of avian chlamydiosis in a pet store and breeding facility leading to mass bird exposures

Chlamydia psittaci is a bacterium that causes chlamydiosis in birds and can cause zoonotic psittacosis in people. In November 2017, we received notification of a suspected case of avian chlamydiosis in a captive cockatiel (Nymphicus hollandicus) that was sold by an online pet bird retail and breeding facility in Washington State. We describe the investigation with emphasis on how environmental sampling was used to guide veterinary and public health interventions. Bird samples were collected either from pooled droppings, pooled plumage or individual nasal and choanal swabs. Environmental samples were obtained by swabbing cleaning mops, tables and cage structures. All samples were tested by polymerase chain reaction and positive samples underwent genotyping. Approximately 1000 birds representing four taxonomic orders were kept within an open-space warehouse. Eight of 14 environmental samples and one of two pooled faecal samples were positive for Chlamydia spp. The contaminating strain of Chlamydia spp. was identified as genotype A. The facility was closed for environmental disinfection, and all psittacines were treated with oral doxycycline for 45 days. Ten of 10 environmental and two of two pooled faecal samples were negative for C. psittaci 11 months after the completion of environmental disinfection and antimicrobial treatment. This investigation highlights the importance of preventing and mitigating pathogen incursion in an online pet retail and breeding facility. Environmental sampling is valuable to guide animal and public health interventions for control of C. psittaci, particularly when large numbers of birds are exposed to the pathogen.

Chlamydia psittaci inclusion membrane protein CPSIT_0842 induces macrophage apoptosis through MAPK/ERK-mediated autophagy

Chlamydia psittaci is a multi-host zoonotic pathogen, which mainly infects poultry and inflicts an appreciable economic burden on the livestock farming industry. C. psittaci inclusion membrane proteins are uniquely positioned at the host-pathogen interface and are important virulence proteins. We have previously confirmed that Incs regulate host cell survival to help Chlamydia sp. evade host-cell-mediated defense mechanisms. However, the role of the Inc, CPSIT_0842, in the regulation of cell death following the establishment of persistent C. psittaci infection remains unknown. This study explored the effect of CPSIT_0842 on the crosstalk between the autophagic and apoptotic pathways in macrophages. Results showed that CPSIT_0842 initiated autophagy and blocked autophagic flux in human macrophages, as indicated by autophagy-related protein LC3-II, Beclin-1, and p62 upregulation, autophagosome accumulation, and lysosomal protein LAMP1 diminution. We also showed that the disruption of autophagic flux had a regulatory effect on CPSIT_0842-induced apoptosis. Moreover, the suppression of autophagy initiation by 3-methyladenine attenuated CPSIT_0842-induced apoptosis. By contrast, the induction of autophagic flux by rapamycin did not significantly affect CPSIT_0842-induced apoptosis. Taken together, these findings demonstrate that CPSIT_0842 induced macrophage apoptosis by initiating incomplete autophagy through the MAPK/ERK/mTOR signaling pathway, which may be instrumental to the ability of C. psittaci to evade the host innate immune response and establish persistent infection. The improved understanding of the autophagic and cell death pathways triggered upon bacterial inclusion will likely help in the development of novel treatment strategies for chlamydia infection.

First detection of Chlamydia avium in healthy Amazon parrots (Amazona aestiva) in Argentina

In recent years, new Chlamydia species, other than Chlamydia psittaci, have been confirmed in birds. One of these new species, Chlamydia avium, was reported mainly in pigeons and parrots in Europe. Analyzing multimucosal swabs obtained from 7 Amazon parrots (Amazona aestiva) from illegal trade and admitted to the Reserva Experimental Horco Molle (Tucuman, Argentina) for their rehabilitation, we describe the finding of the genetic material of C. avium in 2 of these birds. There were no signs compatible with the chlamydiosis-like disease in the studied birds or in the rehabilitation center staff. The use of sensitive and wide-ranging molecular tools is necessary for the detection of all Chlamydiaceae present in birds and would aid in the selection of control measures in wildlife rehabilitation centers to prevent outbreaks in the facilities and the introduction of pathogens in nature. We provide the first molecular evidence of the presence of C. avium in Argentina and a new species of psittacine host.

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.

A Chlamydia psittaci Outbreak in Psittacine Birds in Sardinia, Italy

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

Chlamydia psittaci plasmid-encoded CPSIT_P7 induces macrophage polarization to enhance the antibacterial response through TLR4-mediated MAPK and NF-κB pathways

Although the protective effects of Chlamydia psittaci plasmid-encoded protein CPSIT_P7 as vaccine antigens to against chlamydial infection have been confirmed in our previous study, the function and mechanism of CPSIT_P7 inducing innate immunity in the antibacterial response remain unknown. Here, we found that plasmid protein CPSIT_P7 could induce M1 macrophage polarization upregulating the genes of the surface molecule CD86, proinflammatory cytokines (TNF-α, IL-6, and IL-1β), and antibacterial effector NO synthase 2 (iNOS). During M1 macrophage polarization, macrophages acquire phagocytic and microbicidal competence, which promotes the host antibacterial response. As we observed that CPSIT_P7-induced M1 macrophages could partially reduce the infected mice pulmonary Chlamydia psittaci load. Furthermore, CPSIT_P7 induced M1 macrophage polarization through the TLR4-mediated MAPK and NF-κB pathways. Collectively, our results highlight the effect of CPSIT_P7 on macrophage polarization and provide new insights into new prevention and treatment strategies for chlamydial infection.

Application of Metagenomic Next-Generation Sequencing in the Diagnosis of Pneumonia Caused by Chlamydia psittaci

Psittacosis is an uncommon disease which mainly presents as community-acquired pneumonia (CAP). We aim to apply metagenomic next-generation sequencing (mNGS) as a promising tool in the diagnosis of psittacosis pneumonia and to describe its clinical spectrum to provide physicians with a better understanding and recognition of this disease. Thirteen cases of psittacosis pneumonia were diagnosed by using mNGS. A retrospective analysis of the data on clinical manifestations, laboratory data, computed tomography (CT) images, new diagnosis tools, treatments, and outcomes was summarized. These patients had common symptoms of fever and weakness; some had poor appetite, cough, myalgia, and headache. Ten patients developed acute respiratory distress syndrome (ARDS), among which six patients were severe pneumonia cases and needed ventilator therapy. Most patients got psittacosis pneumonia during the cold season. Ten cases were sporadic, but three were family clustering. All of the 13 patients were traced to an exposure history to birds, cat, or poultry, among which 2 only touched the innards of killed poultry before cooking, which may be an atypical exposure history not been reported before, to our knowledge. Most patients had various degrees of liver dysfunction. Air-space consolidations, along with ground-glass opacities and reticular shadows, were detected on chest CT scan. mNGS takes 48 to 72 h to provide results and helps to diagnose psittacosis. After being diagnosed by mNGS, with effective medicines, all patients finally had complete recoveries. The use of mNGS can improve the diagnostic rate of psittacosis pneumonia and shorten the course of disease control. IMPORTANCE Psittacosis pneumonia is easily underdiagnosed and misdiagnosed. In this study, we use mNGS in the diagnosis of psittacosis pneumonia. We found this disease is prone in the cold season, and touching the innards of killed poultry during cooking may be an atypical exposure history which has not been reported before to our knowledge. There are sporadic cases and family outbreak cases as well. Except for typical symptoms of fever and weakness, headache may be the main and only symptom in some patients. The rate of severe pneumonia is high among inpatients with psittacosis pneumonia, and the incidence of hepatic involvements is also high. Psittacosis pneumonia can be cured if the diagnosis is accurate and in time, even if it is severe pneumonia on admission. Some problems worthy of our attention about psittacosis pneumonia were put forward, such as its sick season, special exposure history, the rate of severe disease, and the high cure rate. mNGS can quickly and objectively detect more rare pathogenic microorganisms in clinical specimens without the need for specific amplification and has an advantage in the diagnosis of rare pathogenic bacteria in difficult cases such as psittacosis pneumonia. The use of mNGS can improve the accuracy and reduce the delay in the diagnosis of psittacosis, which shortens the course of disease control.

Polymorphic Membrane Protein 17G of Chlamydia psittaci Mediated the Binding and Invasion of Bacteria to Host Cells by Interacting and Activating EGFR of the Host

Chlamydia psittaci (C. psittaci) is an obligate intracellular, gram-negative bacterium, and mainly causes systemic disease in psittacine birds, domestic poultry, and wild fowl. The pathogen is threating to human beings due to closely contacted to employees in poultry industry. The polymorphic membrane proteins (Pmps) enriched in C. psittaci includes six subtypes (A, B/C, D, E/F, G/I and H). Compared to that of the 1 pmpG gene in Chlamydia trachomatis (C. trachomatis), the diverse pmpG gene-coding proteins of C. psittaci remain elusive. In the present study, polymorphic membrane protein 17G (Pmp17G) of C. psittaci mediated adhesion to different host cells. More importantly, expression of Pmp17G in C. trachomatis upregulated infections to host cells. Afterwards, crosstalk between Pmp17G and EGFR was screened and identified by MALDI-MS and Co-IP. Subsequently, EGFR overexpression in CHO-K1 cells and EGFR knockout in HeLa 229 cells were assessed to determine whether Pmp17G directly correlated with EGFR during Chlamydial adhesion. Finally, the EGFR phosphorylation was recognized by Grb2, triggering chlamydial invasion. Based on above evidence, Pmp17G possesses adhesive property that serves as an adhesin and activate intracellular bacterial internalization by recognizing EGFR during C. psittaci infection

Detection of Chlamydia psittaci in both blood and bronchoalveolar lavage fluid using metagenomic next-generation sequencing: A case report

RATIONALE

Chlamydia psittaci (C psittaci) is a gram-negative obligate intracellular parasite, with birds as main hosts. The main route of infection in humans is inhalation of aerosols from contaminated animal excreta through the respiratory tract. The main manifestation of C psittaci infection is pneumonia. Patients suffering from severe infection are prone to sepsis and multiple organ failure. We report a case of simultaneous detection of C psittaci in blood and bronchoalveolar lavage fluid using metagenomic next-generation sequencing (mNGS) technology.

PATIENT CONCERNS

The 71-year-old male patient was a farmer with a long history of raising poultry and initial symptoms of fever and muscle pain accompanied by limb weakness and paroxysmal cough.

DIAGNOSES

The patient was diagnosed with sepsis, severe pneumonia, and multiple organ failure.

INTERVENTIONS

Anti-infective therapy with doxycycline and meropenem was applied.

OUTCOMES

The patient's body temperature and infection indicators improved and the chest X-ray findings showed the amelioration of lesions after 18 days of treatment. The patient was discharged without treatment on hospital day 19 due to financial constraints and subsequently died after 7 days.

LESSONS

mNGS is an excellent diagnostic tool when specific pathogens are undetected by traditional assays.

A recombinase polymerase amplification-based assay for rapid detection of Chlamydia psittaci

Chlamydia psittaci is a zoonotic agent of systemic wasting disease in birds and atypical pneumonia in mammalians including humans, constituting a public health risk. A rapid diagnostic assay would be beneficial in screening C. psittaci in the field. In this study, we developed a probe-based recombinase polymerase amplification (RPA) assay for the rapid detection of C. psittaci. The specific primer pairs and probe targeting the conserved region of the outer membrane protein A gene were designed and applied to the real-time real-time RPA assay. The test can be performed at 39°C for 20 min using a portable device, with sensitivities approaching 100 copies of DNA molecules per reaction, with no cross-reaction with other pathogens. The clinical performance of the RPA assay was evaluated in an outbreak of C. psittaci and has high accuracy levels in field applications. The epidemic C. psittaci strains were classed into 2 genotypes: A and C. Collectively, this study offers a promising approach in screening for C. psittaci both in a laboratory setting and in field settings, and RPA can be used as an effective clinical test to monitor outbreaks in domestic fowl populations.

Development of a Plasmid Shuttle Vector System for Genetic Manipulation of Chlamydia psittaci

The obligate intracellular bacterium Chlamydia psittaci is a known avian pathogen causing psittacosis in birds and is capable of zoonotic transmission. In human pulmonary infections, C. psittaci can cause pneumonia associated with significant mortality if inadequately diagnosed and treated. Although intracellular C. psittaci manipulates host cell organelles for its replication and survival, it has been difficult to demonstrate host-pathogen interactions in C. psittaci infection due to the lack of easy-to-handle genetic manipulation tools. Here, we show the genetic transformation of C. psittaci using a plasmid shuttle vector that contains a controllable gene induction system. The 7,553-bp plasmid p01DC12 was prepared from the nonavian C. psittaci strain 01DC12. We constructed the shuttle vector pCps-Tet-mCherry using the full sequence of p01DC12 and the 4,449-bp fragment of Chlamydia trachomatis shuttle vector pBOMB4-Tet-mCherry. pCps-Tet-mCherry includes genes encoding the green fluorescent protein (GFP), mCherry, and ampicillin resistance (AmpR). Target genes can be inserted at a multiple cloning site (MCS). Importantly, these genes can be regulated by a tetracycline-inducible (tet) promoter. Using the pCps-Tet-mCherry plasmid shuttle vector, we show the expression of GFP, as well as the induction of mCherry expression, in C. psittaci strain 02DC15, which belongs to the avian C. psittaci 6BC clade. Furthermore, we demonstrated that pCps-Tet-mCherry was stably retained in C. psittaci transformants. Thus, our C. psittaci plasmid shuttle vector system represents a novel targeted approach that enables the elucidation of host-pathogen interactions.IMPORTANCE Psittacosis, caused by avian C. psittaci, has a major economic impact in the poultry industry worldwide and represents a significant risk for zoonotic transmission to humans. In the past decade, the tools of genetic manipulation have been improved for chlamydial molecular studies. While several genetic tools have been mainly developed in Chlamydia trachomatis, a stable gene-inducible shuttle vector system has not to date been available for C. psittaci In this study, we adapted a C. trachomatis plasmid shuttle vector system to C. psittaci We constructed a C. psittaci plasmid backbone shuttle vector called pCps-Tet-mCherry. The construct expresses GFP in C. psittaci Importantly, exogeneous genes can be inserted at an MCS and are regulated by a tet promoter. The application of the pCps-Tet-mCherry shuttle vector system enables a promising new approach to investigate unknown gene functions of this pathogen.

Metagenomic next-generation sequencing in the diagnosis of severe pneumonias caused by Chlamydia psittaci

PURPOSE

Chlamydia psittaci infection in humans can lead to serious clinical manifestations, including severe pneumonia, adult respiratory distress syndrome, and, rarely, death. Implementation of metagenomic next-generation sequencing (mNGS) gives a promising new tool for diagnosis. The clinical spectrum of severe psittacosis pneumonia is described to provide physicians with a better understanding and to highlight the rarity and severity of severe psittacosis pneumonia.

METHODS

Nine cases of severe psittacosis pneumonia were diagnosed using mNGS. Retrospective analysis of the data on disease progression, new diagnosis tool, treatments, and outcomes, and the findings were summarised.

RESULTS

Frequent symptoms included chills and remittent fever (100%), cough and hypodynamia (100%), and headache and myalgia (77.8%). All patients were severe psittacosis pneumonia developed respiratory failure, accompanied by sepsis in 6/9 patients. mNGS takes 48-72 h to provide the results, and help to identify diagnosis of psittacosis. Laboratory data showed normal or slightly increased leucocytes, neutrophils, and procalcitonin but high C-reactive protein levels. Computed tomography revealed air-space consolidation and ground-glass opacity, which began in the upper lobe of one lung, and spread to both lungs, along with miliary, nodular, or consolidated shadows. One patient died because of secondary infection with Klebsiella pneumoniae, while the other eight patients experienced complete recoveries.

CONCLUSIONS

The use of mNGS can improve accuracy and reduce the delay in diagnosis of psittacosis. Severe psittacosis pneumonia responds well to the timely use of appropriate antibiotics.

Psittacosis Outbreak among Workers at Chicken Slaughter Plants, Virginia and Georgia, USA, 2018

During August–October, 2018, an outbreak of severe respiratory illness was reported among poultry slaughter plant workers in Virginia and Georgia, USA. A multiorganizational team investigated the cause and extent of illness, determined that the illness was psittacosis, and evaluated and recommended controls for health hazards in the workplace to prevent additional cases.

SURVEILLANCE FOR CHLAMYDIA SPP. WITH MULTILOCUS SEQUENCE TYPING ANALYSIS IN WILD AND CAPTIVE BIRDS IN VICTORIA, AUSTRALIA

Chlamydia psittaci typically infects birds and can cause outbreaks of avian chlamydiosis, but it also has the potential to cause zoonotic disease (psittacosis) in humans. To better understand the epidemiology of C. psittaci in Victoria, Australia, we conducted opportunistic sampling of more than 400 wild and captive birds presented to the Australian Wildlife Health Centre at Zoos Victoria's Healesville Sanctuary for veterinary care between December 2014 and December 2015. Samples were screened for the presence of chlamydial DNA using quantitative PCR, and positive samples were subjected to multilocus sequence typing analysis. The results showed a significantly higher prevalence of infection in captive birds (8%; 9/113) compared to wild birds (0.7%; 2/299). Multilocus sequence typing analysis revealed that C. psittaci sequence type 24 was detected in both wild and captive birds in the local region, while C. psittaci sequence type 27 was detected for the first time in an Australian avian host. The generally low prevalence of C. psittaci detection points to a generally low zoonotic risk to veterinary and support staff, although this risk may be higher when handling captive birds, where the prevalence of C. psittaci infection was almost 10-fold higher. Even with low rates of C. psittaci detection, appropriate hygiene and biosecurity practices are recommended due to the serious human health implications of infection with this pathogen.

Chlamydiaceae in wild, feral and domestic pigeons in Switzerland and insight into population dynamics by Chlamydia psittaci multilocus sequence typing

Feral pigeons, common wood pigeons and Eurasian collared doves are the most common representatives of the Columbidae family in Switzerland and are mostly present in highly populated, urban areas. Pigeons may carry various members of the obligate intracellular Chlamydiaceae family, particularly Chlamydia (C.) psittaci, a known zoonotic agent, and C. avium. The objective of the study was to identify the infection rates of common free-roaming pigeons for different Chlamydia species with the overall aim to assess the risk pigeons pose to public health. In this study, 431 pigeons (323 feral pigeons, 34 domestic pigeons, 39 Eurasian collared doves, 35 common wood pigeons) from several geographic locations in Switzerland were investigated for the presence of Chlamydiaceae. Samples consisted of pooled choanal-cloacal swabs (n = 174), liver samples (n = 52), and paired swab and liver samples from 205 pigeons (n = 410). All 636 samples were screened using a Chlamydiaceae family-specific 23S rRNA real-time PCR (qPCR). Subsequent species identification was performed by DNA-microarray assay, sequencing of a 16S rRNA gene fragment and a C. psittaci specific qPCR. In total, 73 of the 431 pigeons tested positive for Chlamydiaceae, of which 68 were positive for C. psittaci, four were C. avium-positive and one pigeon was co-infected with C. avium and C. psittaci. The highest infection rates were detected in feral (64/323) and domestic pigeons (5/34). Common wood pigeons (2/35) and Eurasian collared doves (2/39) revealed lower infection rates. Additionally, multilocus sequence typing of twelve selected C. psittaci-positive samples revealed closely related sequence types (ST) between and within different Swiss cities. Furthermore, liver and corresponding swab samples from the same bird were colonized by the same ST. Considering the high infection rates of C. psittaci in domestic and feral pigeons, close or frequent contact to these birds poses a human health risk.

Chlamydiosis in farmed chickens in Slovakia and zoonotic risk for humans

INTRODUCTION

Chlamydia psittaci is an obligate intracellular Gram-negative bacterium causing respiratory disease (chlamydiosis) or asymptomatic carriage in poultry. In humans, it is a zoonotic agent of ornithosis/psittacosis. Due to low awareness of the disease and variable clinical presentation, psittacosis is often remains unrecognised as such by general practitioners. Zoonotic transfer occurs through inhalation of contaminated aerosols, and originates from feathers, faecal material and respiratory tract exudates.

OBJECTIVE

The aim of this study was to investigate chickens for the presence of Chlamydia sp. from pharyngeal and cloacal swabs and review the zoonotic risk for humans.

MATERIAL AND METHODS

138 clinically healthy chickens from farms in Slovakia were examined for the presence of Chlamydia sp. The age of the chickens was 6 months. Two different samples were used - pharyngeal swabs and cloacal swabs. Each sample was examined by the molecular PCR method, and in the case of a positive result the identity of the obtained sequences was examined by a BLAST search.

RESULTS

Of the total number of 276 examined samples from 138 chickens, 19 (6.9%) showed positivity for C. psittaci infection, 12 (8.7%) which were positive from pharyngeal swabs and 7 (5.1%) from cloacal swabs. None of the chickens were positive in both samples. Phylogenetic examination of the 19 isolates identified in the study, based on the 23S rRNA gene sequence, revealed that the isolates obtained were identical with C. psittaci, and genetically very close to genotypes B and genotype E.

CONCLUSIONS

C. psittaci infections are apparently emerging in chickens. Chicken-processing plant employees should be considered a risk group for human psittacosis. There is a need for higher awareness and for efficient risk assessment and management.

Development of a Novel PmpD-N ELISA for Chlamydia psittaci Infection

OBJECTIVE

Chlamydia psittaci is an avian respiratory pathogen and zoonotic agent. The wide prevalence of C. psittaci poses a threat to the poultry industry and its employees. However, few commercial kits are available for detecting avian antibodies excluding the in-house ELISA kit. In this study, we developed a novel ELISA kit for detecting antibodies against C. psittaci based on the N-terminal fragment of polymorphic outer membrane protein D (PmpD-N) as the coating antigen.

METHODS

The antigen concentrations, primary antibody, and cut-off value were determined and optimized. The ELISA, designated PmpD-N ELISA, was assessed for sensitivity, specificity, and concordance using sera samples from 48 experimentally infected and 168 uninfected SPF chickens.

RESULTS

The sensitivity and specificity of PmpD-N ELISA were 97.9%, 100%, respectively, while the concordance was 98.1% as compared to that of MOMP-ELISA. No cross-reaction with positive sera for other avian pathogens was found. Using PmpD-N ELISA, 799/836 clinical samples were positive, including 93.0% and 98.1% positivity in layers and broilers, respectively.

CONCLUSION

These data indicate that indirect ELISA with PmpD-N as the antigen candidate is a promising approach for the surveillance of C. psittaci infection.

Chlamydia psittaci: a relevant cause of community-acquired pneumonia in two Dutch hospitals

BACKGROUND

Of all hospitalised community-acquired pneumonias (CAPs) only a few are known to be caused by Chlamydia psittaci. Most likely the reported incidence, ranging from of 0% to 2.1%, is an underestimation of the real incidence, since detection of psittacosis is frequently not incorporated in the routine microbiological diagnostics in CAP or serological methods are used.

METHODS

C. psittaci real-time polymerase chain reaction (PCR) was routinely performed on the sputum of 147 patients hospitalised with CAP, who participated in a clinical trial conducted in two Dutch hospitals. In 119/147 patients the paired complement fixation test (CFT) was also performed for the presence of Chlamydia antibodies. Positive CFTs were investigated by micro- Immunofluorescence for psittacosis specificity. Case criteria for psittacosis were a positive PCR or a fourfold rise of antibody titre in CFT confirmed by micro- Immunofluorescence. Furthermore, we searched for parameters that could discriminate psittacosis from CAPs with other aetiology.

RESULTS

7/147 (4.8%) patients were diagnosed with psittacosis: six with PCR and one patient with a negative PCR, but with CFT confirmed by micro- Immunofluorescence. Psittacosis patients had had a higher temperature (median 39.6 vs. 38.2 °C;) but lower white blood cell count (median 7.4 vs. 13.7 x 109/l) on admission compared with other CAP patients.

CONCLUSION

In this study, C. psittaci as CAP-causing pathogen was much higher than previously reported. To detect psittacosis, PCR was performed on all CAP patients for whom a sputum sample was available. For clinical use, PCR is a fast method and sputum availability allows genotyping; additional serology can optimise epidemiological investigations.

Detection of CHLAMYDIA PSITTACI in feral pigeons (COLUMBA LIVIA DOMESTICA) in Slovakia and their characterisation

INTRODUCTION AND OBJECTIVES

Chlamydia psittaci, an obligate intracellular bacterium, which is the etiologic agent of avian chlamydiosis in birds and ornithosis/psittacosis in humans, has been reported to be one of the most common pathogens found in feral pigeons worldwide, and thus constitutes a zoonotic risk. The aim of the study was to investigate pigeons in Slovakia living in areas in close proximity to humans for the presence of C. psittaci, using pharyngeal and cloacal swabs.

MATERIAL AND METHODS

122 clinically healthy pigeons from different geographical regions of Slovakia were examined for the presence of C. psittaci. The adult pigeons of both genders were captured during the summer period in the urban centres of Slovakian towns. Each sample was examined by molecular method PCR, and in the case of positive result the identity of the obtained sequence was examined by a BLAST search.

RESULTS

Of the total number of 244 examined samples, 14 (5.7%) showed positivity for C. psittaci infection, 5 of which were from pharyngeal swabs (4.1%) and 9 from cloacal swabs (7.4%). A positive result was detected in 13 pigeons (10.7%). Phylogenetic analysis showed that all the positive samples are genetically very close to genotypes B and genotype E.

CONCLUSION

Phylogenetic examination of the 14 isolates of C. psittaci identified in the presented study, based on 23S rRNA gene sequence, revealed their close relationship with C. psittaci genotypes B and E. Both genotypes are predominantly prevalent in pigeons and both can be transmitted to humans. Therefore, it is necessary to perform screening examinations of animals and analyse the epidemiological factors affecting the way of transmission and circulation of pathogen.