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

Molecular detection of Chlamydia psittaci in birds: a systematic review

Molecular methods are currently the most sensitive for detecting Chlamydia psittaci in birds. Most laboratories have developed their own molecular assays or adapted published protocols, often making slight modifications to fit their specific study purposes. The sensitivity and specificity of a molecular test depend on the target gene, primer sequences, types of molecular test, DNA extraction method, and sampling methods. We reviewed 120 articles published between 2000 and 2020 to compile information on the molecular detection of C. psittaci in birds. Of the ten genomic targets currently available to detect C. psittaci in birds, the ompA gene was the most widely used. In published surveillance studies, of the fourteen molecular test types, conventional PCR and quantitative PCR were applied the most. A testing strategy using a hierarchical approach that includes molecular tests of genus- and species-specific targets is recommended to detect other avian chlamydial species besides the well-recognized C. psittaci. Samples should be sourced from both the respiratory and gastrointestinal tracts whenever possible for better accuracy. High-quality DNA can be obtained when the sample is preserved in optimal medium and temperature, and an optimized DNA extraction protocol is applied. Standardization and validation of molecular Chlamydia tests are needed to enhance the comparability and reliability of assays to detect C. psittaci and other chlamydiae species in birds.RESEARCH HIGHLIGHTSHierarchical molecular testing is recommended for the detection of avian C. psittaci.Key molecular tests for surveillance were conventional PCR and quantitative PCR.The most used genomic target to detect C. psittaci in birds was the ompA gene.

Circulation of avian Chlamydia abortus in the Netherlands and community-acquired pneumonia: an outbreak investigation and retrospective cohort study

BACKGROUND

In 2021, a novel group of Chlamydia strains in wild birds was classified as avian Chlamydia abortus, with unknown zoonotic potential. We report relevant features of avian C abortus infections from a Dutch family cluster and unrelated historical cases using clinical, epidemiological, and microbiological data.

METHODS

An outbreak of avian C abortus started in the Netherlands in December, 2022. Source investigation was done using questionnaires to interview patients and environmental sampling. The outbreak strain of avian C abortus was cultured from three patients from whom sufficient material was available for culture and underwent whole-genome analysis. The outbreak strains and retrospective cohort study strains previously submitted to the National Human Psittacosis surveillance programme in the Netherlands between 2010 and 2022 were typed by partial ompA sequencing. Strains with the same aberrant ompA genotype were further analysed with XerC gene plasmid analysis and compared with closely related Chlamydia sequences available in GenBank.

FINDINGS

An avian C abortus strain caused a cluster of respiratory illness in four family members. Three patients were hospitalised with community-acquired pneumonia, one of whom was admitted to the intensive care unit. The faeces of wild birds were considered a probable source for the index infection. For two family members, human-to-human transmission was a plausible route. Ten historical cases could be identified with avian C abortus with the same ompA genotype. All patients had been admitted to hospital, at least five developed pneumonia, and one died.

INTERPRETATION

This cluster supports that avian C abortus strains can cause human infections and underlines that human-to-human transmission should be considered when tracing the source of such infections.

FUNDING

National Institute for Public Health and the Environment and Dutch Ministry of Agriculture, Fisheries, Food Security and Nature.

TRANSLATION

For the Dutch translation of the abstract see Supplementary Materials section.

Zoonotic transmission of Chlamydia felis from domestic cats; A case series of chronic follicular conjunctivitis in humans

We present three cases of chronic follicular conjunctivitis resulting from the zoonotic transmission of Chlamydia felis from domestic cats. Our objective is to raise awareness regarding the potential zoonotic transmission of Chlamydia felis from domestic cats and describe the methodology for definitive pathogen identification using Polymerase Chain Reaction (PCR) and subsequent sequence analysis, a useful tool in the identification of these rare pathogens. We discuss the factors that could be contributing to the potential under-diagnosis of zoonotic C. felis infections and propose a treatment regime for cases of C. felis-related conjunctivitis.

Development and evaluation of a novel quenching probe PCR (GENECUBE) assay for rapidly detecting and distinguishing between Chlamydia pneumoniae and Chlamydia psittaci

Early detection of the family Chlamydiaceae as pathogens is essential worldwide for the rapid and sufficient management of atypical pneumonia. GENECUBE (TOYOBO) is a novel fully automated gene analyzer capable of amplifying and detecting target DNAs within 50 min. In this study, we developed a new PCR assay with a specific quenching probe (PCR-QC assay) for rapidly distinguishing between Chlamydia pneumoniae (CPN) and Chlamydia psittaci (CPS). The PCR-QC assay enabled us to precisely and simultaneously detect the 2 different types of DNA fragments even in a mixed sample by identifying unique melting temperatures. Next, we examined a total of 300 frozen samples from patients with respiratory tract infection using the PCR-QC assay and the cell culture method as the gold standard. Kappa index for agreement between the PCR-QC assay and the culture method was 0.43 (95% confidential interval (CI): 0.08-0.78). The sensitivity and specificity of the PCR-QC assay were 36.3% (4/11; 95% CI: 10.9-69.2%)) and 99.0% (286/289; 95% CI: 97.0-99.8%), respectively. The samples positive for CPN (n = 13) or CPS (n = 1) by either method were also examined by a conventional PCR TaqMan assay, which produced the same results as those from the PCR-QC assay. Furthermore, the PCR-QC assay using GENECUBE shortened the full detection time for CPN or CPS (within 50 min vs. more than 2 to 3 h) compared with conventional PCR TaqMan assays. Therefore, the new PCR-QC assay system equipped with GENECUBE is useful for rapidly detecting CPN or CPS pathogens in clinical laboratory, and may improve the management of atypical pneumonia.

Development of a species-specific real-time PCR test for Chlamydia psittaci and its employment in the investigation of zoonotic transmission from racing pigeons in Denmark

Species-specific detection of Chlamydia psittaci is challenging and all published PCR tests have so far shown deficiencies in specificity or sensitivity. The present investigation reports on the development of a species-specific real-time PCR assay for C. psittaci. The test is based on an 84 bp indel in a gene of unknown function that is unique to C. psittaci. The Cps-indel84-PCR assay was validated on a wide range of chlamydial and other bacterial strains as well as on clinical samples from animals and humans in two different diagnostic laboratories in Germany and Denmark. Furthermore, the test was employed for investigating samples from racing pigeon flocks in Denmark. The evaluation showed that the Cps-indel84-PCR assay has excellent test characteristics and is a highly reliable method for identifying C. psittaci in clinical samples both from humans and animals.

Antibiotic use and prescription and its effects on Enterobacteriaceae in the gut in children with mild respiratory infections in Ho Chi Minh City, Vietnam. A prospective observational outpatient study

BACKGROUND AND OBJECTIVES

Treatment guidelines do not recommend antibiotic use for acute respiratory infections (ARI), except for streptococcal pharyngitis/tonsillitis and pneumonia. However, antibiotics are prescribed frequently for children with ARI, often in absence of evidence for bacterial infection. The objectives of this study were 1) to assess the appropriateness of antibiotic prescriptions for mild ARI in paediatric outpatients in relation to available guidelines and detected pathogens, 2) to assess antibiotic use on presentation using questionnaires and detection in urine 3) to assess the carriage rates and proportions of resistant intestinal Enterobacteriaceae before, during and after consultation.

MATERIALS AND METHODS

Patients were prospectively enrolled in Children's Hospital 1, Ho Chi Minh City, Vietnam and diagnoses, prescribed therapy and outcome were recorded on first visit and on follow-up after 7 days. Respiratory bacterial and viral pathogens were detected using molecular assays. Antibiotic use before presentation was assessed using questionnaires and urine HPLC. The impact of antibiotic usage on intestinal Enterobacteriaceae was assessed with semi-quantitative culture on agar with and without antibiotics on presentation and after 7 and 28 days.

RESULTS

A total of 563 patients were enrolled between February 2009 and February 2010. Antibiotics were prescribed for all except 2 of 563 patients. The majority were 2nd and 3rd generation oral cephalosporins and amoxicillin with or without clavulanic acid. Respiratory viruses were detected in respiratory specimens of 72.5% of patients. Antibiotic use was considered inappropriate in 90.1% and 67.5%, based on guidelines and detected pathogens, respectively. On presentation parents reported antibiotic use for 22% of patients, 41% of parents did not know and 37% denied antibiotic use. Among these three groups, six commonly used antibiotics were detected with HPLC in patients' urine in 49%, 40% and 14%, respectively. Temporary selection of 3rd generation cephalosporin resistant intestinal Enterobacteriaceae during antibiotic use was observed, with co-selection of resistance to aminoglycosides and fluoroquinolones.

CONCLUSIONS

We report overuse and overprescription of antibiotics for uncomplicated ARI with selection of resistant intestinal Enterobacteriaceae, posing a risk for community transmission and persistence in a setting of a highly granular healthcare system and unrestricted access to antibiotics through private pharmacies.

REGISTRATION

This study was registered at the International Standard Randomised Controlled Trials Number registry under number ISRCTN32862422: http://www.isrctn.com/ISRCTN32862422.

Chlamydia psittaci in fulmars on the Faroe Islands: a causative link to South American psittacines eight decades after a severe epidemic

A psittacosis epidemic linked to fulmar hunting occurred on the Faroe Islands in the 1930s. This study investigates a plausible explanation to the 20% human mortality in this outbreak. Phylogenetic analysis showed that Chlamydia psittaci isolated from fulmars were closely related to the highly virulent 6BC strains from psittacines and are compatible with an acquisition by fulmars of an ancestor of the 6BC clade in the 1930s. This supports the hypothesis that the outbreak on the Faroe Islands started after naïve fulmars acquired C. psittaci from infected dead parrots thrown overboard when shipped to Europe in the 1930s.

Laboratory methods for case finding in human psittacosis outbreaks: a systematic review

Background

Psittacosis outbreak investigations require rapid identification of cases in order to trace possible sources and perform public health risk assessments. In recent outbreaks in the Netherlands, such investigations were hampered by the non-specificity of laboratory testing methods to identify human Chlamydia psittaci infections.

Method

A systematic search of PubMed and Scopus databases of literature published between 01 January, 1986 and 03 July, 2017 was done to find best practices of laboratory-testing methods used in psittacosis outbreaks of two or more human cases. Reference lists of included articles were hand searched to identify additional articles.

Results

Thirty-seven eligible articles were identified, describing 44 human psittacosis outbreaks in 12 countries. Laboratory tests performed were PCR (with various targets), serologic tests (complement binding reactions, ELISA’s, immunofluorescence tests and immuno-peroxidase tests) and culture, in various combinations. The literature provided no ‘gold standard’ laboratory testing strategy to identify recent human C. psittaci infections. In most psittacosis outbreaks, for a considerable number of cases (or tested individuals in an exposed cohort), C. psittaci infection could not be confirmed, nor excluded as causative pathogen. None of the testing strategies was found to be suitable for (nearly) full case finding.

Conclusion

PCR enables rapid identification of human psittacosis patients and helps source finding by genotyping but has the disadvantage that sensitivity is high only in the acute phase. In outbreak situations, there is often a time delay and therefore, there is a need for new serologic testing methods next to PCR, with good specificity and sensitivity. Moreover, serum is easier to collect than the preferred diagnostic materials for PCR. A serologic test that can reliably confirm infection status without the necessity of convalescent serum sampling would enhance case finding, source tracing, identification of risk factors and assessment of burden of disease in various settings.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3317-0) contains supplementary material, which is available to authorized users.

Chlamydia caviae Causing Community-Acquired Pneumonia: An Emerging Zoonosis

We describe a case of community-acquired pneumonia due to Chlamydia caviae in a patient with no direct animal exposure, raising questions about the zoonotic reservoirs and potential transmission routes. Genotyping of Chamydia isolates that cause pneumonia should be performed for a precise diagnosis and to initiate adequate infection control measures.

Viral and atypical bacterial aetiologies of infection in hospitalised patients admitted with clinical suspicion of influenza in Thailand, Vietnam and Indonesia

Background

Influenza constitutes a leading cause of morbidity and mortality worldwide. There is limited information about the aetiology of infection presenting clinically as influenza in hospitalised adults and children in South-East Asia. Such data are important for future management of respiratory infections.

Objectives

To describe the aetiology of infection presenting clinically as influenza in those hospitalised in South-East Asia.

Methods

Respiratory specimens archived from July 2008 to June 2009 from patients hospitalised with suspected influenza from Indonesia, Thailand and Vietnam were tested for respiratory viruses and atypical bacteria by polymerase chain reaction.

Results

A total of 1222 patients’ samples were tested. Of 1222, 776 patients (63·5%) were under the age of 5. Viruses detected included rhinoviruses in 229 of 1222 patients (18·7%), bocaviruses in 200 (16·4%), respiratory syncytial viruses in 144 (11·8%), parainfluenza viruses in 140 (11·5%; PIV1: 32; PIV2: 12; PIV3: 71; PIV4: 25), adenovirus in 102 (8·4%), influenza viruses in 93 (7·6%; influenza A: 77; influenza B: 16) and coronaviruses in 23 (1·8%; OC43: 14; E229: 9). Bacterial pathogens were Mycoplasma pneumoniae (n = 33, 2·7%), Chlamydophila psittaci (n = 2), C. pneumoniae (n = 1), Bordetella pertussis (n = 1) and Legionella pneumophila (n = 2). Overall, in-hospital case fatality rate was 29 of 1222 (2·4%).

Conclusion

Respiratory viruses were the most commonly detected pathogens in patients hospitalised with a clinical suspicion of influenza. Rhinovirus was the most frequently detected virus, and M. pneumoniae, the most common atypical bacterium. The low number of detected influenza viruses demonstrates a low benefit for empirical oseltamivir therapy, unless during an influenza outbreak.

Evaluation of Patients with Community-Acquired Pneumonia Caused by Zoonotic Pathogens in an Area with a High Density of Animal Farms

Intensive animal farming could potentially lead to outbreaks of infectious diseases. Clinicians are at the forefront of detecting unusual diseases, but the lack of specificity of zoonotic disease symptoms makes this a challenging task. We evaluated patients with community-acquired pneumonia (CAP) with known and unknown aetiology in an area with a high livestock density and a potential association with animal farms in the proximity. Between 2008 and 2009, a period coinciding with a large Q fever outbreak in the Netherlands, patients with CAP were tested for the presence of possible respiratory pathogens. The presence and number of farm animals within 1 km of the patients' home address were assessed using geographic information system (GIS) and were compared between cases and age-matched control subjects. Of 408 patients with CAP, pathogens were detected in 275 (67.4%) patients. The presence of sheep and the number of goats were associated with CAP caused by Coxiella burnetii in a multiple logistic regression model (P < 0.05). CAP with unknown aetiology was not associated with the presence of animal farms (P > 0.10). The use of GIS in combination with aetiology of CAP could be potentially used to target diagnostics and to identify outbreaks of rare zoonotic disease.

Improving the molecular diagnosis of Chlamydia psittaci and Chlamydia abortus infection with a species-specific duplex real-time PCR

Chlamydia psittaci and Chlamydia abortus are closely related intracellular bacteria exhibiting different tissue tropism that may cause severe but distinct infection in humans. C. psittaci causes psittacosis, a respiratory zoonotic infection transmitted by birds. C. abortus is an abortigenic agent in small ruminants, which can also colonize the human placenta and lead to foetal death and miscarriage. Infections caused by C. psittaci and C. abortus are underestimated mainly due to diagnosis difficulties resulting from their strict intracellular growth. We developed a duplex real-time PCR to detect and distinguish these two bacteria in clinical samples. The first PCR (PCR1) targeted a sequence of the 16S-23S rRNA operon allowing the detection of both C. psittaci and C. abortus. The second PCR (PCR2) targeted the coding DNA sequence CPSIT_0607 unique to C. psittaci. The two PCRs showed 100 % detection for ≥ 10 DNA copies per reaction (1000 copies ml(- 1)). Using a set of 120 samples, including bacterial reference strains, clinical specimens and infected cell culture material, we monitored 100 % sensitivity and 100 % specificity for the detection of C. psittaci and C. abortus for PCR1. When PCR1 was positive, PCR2 could discriminate C. psittaci from C. abortus with a positive predictive value of 100 % and a negative predictive value of 88 %. In conclusion, this new duplex PCR represents a low-cost and time-saving method with high-throughput potential, expected to improve the routine diagnosis of psittacosis and pregnancy complication in large-scale screening programs and also during outbreaks.

Typing of Chlamydia psittaci to monitor epidemiology of psittacosis and aid disease control in the Netherlands, 2008 to 2013

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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.

Evaluation of yield of currently available diagnostics by sample type to optimize detection of respiratory pathogens in patients with a community-acquired pneumonia

BACKGROUND

For the detection of respiratory pathogens, the sampling strategy may influence the diagnostic yield. Ideally, samples from the lower respiratory tract are collected, but they are difficult to obtain.

OBJECTIVES

In this study, we compared the diagnostic yield in sputum and oropharyngeal samples (OPS) for the detection of respiratory pathogens in patients with community-acquired pneumonia (CAP), with the objective to optimize our diagnostic testing algorithm.

METHODS

Matched sputum samples, OPS, blood cultures, serum, and urine samples were taken from patients (>18 years) with CAP and tested for the presence of possible respiratory pathogens using bacterial cultures, PCR for 17 viruses and five bacteria and urinary antigen testing.

RESULTS

When using only conventional methods, that is, blood cultures, sputum culture, urinary antigen tests, a pathogen was detected in 49·6% of patients (n = 57). Adding molecular detection assays increased the yield to 80%. A pathogen was detected in 77 of the 115 patients in OPS or sputum samples by PCR. The sensitivity of the OPS was lower than that of the sputum samples (57% versus 74%). In particular, bacterial pathogens were more often detected in sputum samples. The sensitivity of OPS for the detection of most viruses was higher than in sputum samples (72% versus 66%), except for human rhinovirus and respiratory syncytial virus.

CONCLUSION

Addition of PCR on both OPS and sputum samples significantly increased the diagnostic yield. For molecular detection of bacterial pathogens, a sputum sample is imperative, but for detection of most viral pathogens, an OPS is sufficient.

The value of signs and symptoms in differentiating between bacterial, viral and mixed aetiology in patients with community-acquired pneumonia

Current diagnostics for community-acquired pneumonia (CAP) include testing for a wide range of pathogens, which is costly and not always informative. We compared clinical and laboratory parameters of patients with CAP caused by different groups of pathogens to evaluate the potential for targeted diagnostics and directed treatment. In a prospective study, conducted between April 2008 and April 2009, adult patients with CAP were tested for the presence of a broad range of possible respiratory pathogens using bacterial cultures, PCR, urinary antigen testing and serology. Of 408 patients with CAP, pathogens were detected in 263 patients (64.5%). Streptococcus pneumoniae and influenza A virus were the most frequently identified bacterial and viral pathogens, respectively. Age had a significant effect on the prediction of aetiology (P = 0.054), with an increase in the relative contribution of viruses with advancing age. Multivariate analyses further showed that the presence of cough increased the likelihood of detecting a viral pathogen [odds ratio (OR) 5.536, 95% confidence interval (CI) 2.130-14.390], the presence of immunodeficiency decreased the likelihood of detecting a bacterial pathogen (OR 0.595, 95 % CI 0.246-1.437) and an increase in pneumonia severity index score increased the likelihood of detecting a pathogen in general. Although several variables were independently associated with the detection of a pathogen group, substantial overlap meant there were no reliable clinical predictors to distinguish aetiologies. Therefore, testing for common respiratory pathogens is still necessary to optimize treatment.

Viral and bacterial aetiology of community-acquired pneumonia in adults

BACKGROUND

Modern molecular techniques reveal new information on the role of respiratory viruses in community-acquired pneumonia. In this study, we tried to determine the prevalence of respiratory viruses and bacteria in patients with community-acquired pneumonia who were admitted to the hospital.

METHODS

Between April 2008 and April 2009, 408 adult patients (aged between 20 and 94 years) with community-acquired pneumonia were tested for the presence of respiratory pathogens using bacterial cultures, real-time PCR for viruses and bacteria, urinary antigen testing for Legionella and Pneumococci and serology for the presence of viral and bacterial pathogens.

RESULTS

Pathogens were identified in 263 (64·5%) of the 408 patients. The most common single organisms in these 263 patients were Streptococcus pneumoniae (22·8%), Coxiella burnetii (6·8%) and influenza A virus (3·8%). Of the 263 patients detected with pathogens, 117 (44·5%) patients were positive for one or more viral pathogens. Of these 117 patients, 52 (44·4%) had no bacterial pathogen. Multiple virus infections (≥2) were found in 16 patients.

CONCLUSION

In conclusion, respiratory viruses are frequently found in patients with CAP and may therefore play an important role in the aetiology of this disease.

Real-time PCR as a diagnostic tool for bacterial diseases

In recent years, quantitative real-time PCR tests have been extensively developed in clinical microbiology laboratories for routine diagnosis of infectious diseases, particularly bacterial diseases. This molecular tool is well-suited for the rapid detection of bacteria directly in clinical specimens, allowing early, sensitive and specific laboratory confirmation of related diseases. It is particularly suitable for the diagnosis of infections caused by fastidious growth species, and the number of these pathogens has increased recently. This method also allows a rapid assessment of the presence of antibiotic resistance genes or gene mutations. Although this genetic approach is not always predictive of phenotypic resistances, in specific situations it may help to optimize the therapeutic management of patients. Finally, an approach combining the detection of pathogens, their mechanisms of antibiotic resistance, their virulence factors and bacterial load in clinical samples could lead to profound changes in the care of these infected patients.

Frequent occurrence of human-associated microsporidia in fecal droppings of urban pigeons in amsterdam, the Netherlands

Human-associated microsporidia were frequently observed in fecal samples of 331 feral pigeons in Amsterdam, The Netherlands, obtained during high- and low-breeding periods. Thirty-six of 331 samples (11%) contained the human pathogens Enterocytozoon bieneusi (n = 18), Encephalitozoon hellem (n = 11), Encephalitozoon cuniculi (n = 6), and Encephalitozoon intestinalis (n = 1); 5 samples contained other microsporidia. Pigeon feces can be an important source of human microsporidian infection.

New real-time PCR tests for species-specific detection of Chlamydophila psittaci and Chlamydophila abortus from tissue samples

Chlamydophila psittaci and Chlamydophila abortus are the causative agents of avian chlamydiosis (psittacosis) and ovine enzootic abortion, respectively. Both pathogens are known to possess zoonotic potential. Due to their close genetic relatedness, direct and rapid species identification is difficult. In the present study, new real-time PCR assays are reported for both species. The tests are based on highly specific probes targeting the ompA gene region and were conducted as duplex PCRs including an internal amplification control. The Cp. psittaci assay successfully passed a proficiency test at national level. Examination of field samples revealed Cp. psittaci as the dominating species in birds, but also Cp. abortus in a few psittacines. Real-time PCR assays for species-specific detection of Cp. psittaci and Cp. abortus are suited for routine diagnosis, which renders them important tools for the recognition of outbreaks of psittacosis and ovine enzootic abortion.

Genotyping of Chlamydophila psittaci in human samples

Chlamydophila (formerly Chlamydia) psittaci genotypes A, B, C, and a new genotype most similar to the 6BC type strain were found in 10 humans with psittacosis by outer membrane protein A gene sequencing. Genotypes B (n = 3) and C (n = 1) are endemic in nonpsittacine European birds. These birds may represent an important part of the zoonotic reservoir.

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.

Prevalence of Chlamydophila psittaci in fecal droppings from feral pigeons in Amsterdam, The Netherlands

In many cities, the feral rock dove is an abundant bird species that can harbor Chlamydophila psittaci. We determined the prevalence and genotype of C. psittaci in fresh fecal samples from feral pigeons in Amsterdam, The Netherlands. The prevalence was 7.9% overall (26/331; 95% confidence interval, 5 to 11). Ten genotyped PCR-positive samples were all genotype B.