A New SNP-Based Genotyping Method for C. psittaci: Application to Field Samples for Quick Identification

Chlamydia (C.) psittaci is the causative agent of avian chlamydiosis and human psittacosis. In this study, we extracted single-nucleotide polymorphisms (SNPs) from the whole genome sequences of 55 C. psittaci strains and identified eight major lineages, most of which are host-related. A combined PCR/high-resolution melting (HRM) assay was developed to screen for eight phylogenetically informative SNPs related to the identified C. psittaci lineages. The PCR-HRM method was validated on 11 available reference strains and with a set of 118 field isolates. Overall, PCR-HRM clustering was consistent with previous genotyping data obtained by ompA and/or MLST analysis. The method was then applied to 28 C. psittaci-positive samples from animal or human cases. As expected, PCR-HRM typing results from human samples identified genotypes linked to ducks and pigeons, a common source of human exposure, but also to the poorly described Mat116-like genotype. The new genotyping method does not require time-consuming sequencing and allows a quick identification of the source of infection.

Prevalence and Zoonotic Potential of Avian Chlamydia in Croatia

Background: Zoonotic Chlamydia (C.) psittaci, can be found in different bird species, but also in other animals and humans. Recently, new species have been described, as C. gallinacea and C. avium, changing the perspective of a single causative agent of avian chlamydiosis. Genotypes of C. psittaci differ, according to their pathogenicity, and the ones isolated from parrots, turkeys and ducks are particularly pathogenic to bird breeders or owners, veterinarians, poultry farms and slaughterhouse workers. Infections in humans may pass unapparent or to the onset of systemic lung inflammation. Asymptomatic infection is most commonly found in birds, but acute systemic or chronic infections are also possible. Material and Methods: Presence of C. psittaci in birds in Croatia must be reported by law, and all registered flocks of pigeons, parrots and other birds must be examined once, and pet shops at least twice a year. In the period from 2008 to 2017, a total of 3283 avian samples were examined by real-time PCR and the presence of Chlamydiaceae, C. psittaci and C. gallinacea were detected in faecal samples or swabs. Results and Conclusions: In total, 12% of the samples were found positive for Chlamydiaceae. From the 2015, the presence of C. psittaci has also routinely been determined, whereas 34.01% positive avian samples proved to be C. psittaci. Findings of chlamydia in various avian species indicates the importance of proper implementation of the protective measures, by taking into account the zoonotic potential of chlamydia originating from birds and poultry.

Detection of Chlamydia psittaci and Chlamydia ibidis in the Endangered Crested Ibis (Nipponia nippon)

Chlamydia spp. are a group of obligate intracellular pathogens causing a number of diseases in animals and humans. Avian chlamydiosis (AC), caused by Chlamydia psittaci (C. psittaci) as well as new emerging C. avium, C. gallinacea and C. ibidis, have been described in nearly 500 avian species worldwidely. The Crested Ibis (Nipponia nippon) is a world endangered avian species with limited population and vulnerable for various infections. To get a better understanding of the prevalence of Chlamydia spp. in the endangered Crested Ibis, faecal samples were collected and analysed. The results confirmed that 20.20% (20/99) of the faecal samples were positive for Chlamydiaceae and were identified as C. ibidis with co-existence of C. psittaci in one of the 20 positive samples. In addition, ompA sequence of C. psittaci obtained in this study was classified into the provisional genotype Matt116, while that of C. ibidis showed high genetic diversity, sharing only 77% identity with C. ibidis reference strain 10-1398/6. We report for the first time the presence of C. ibidis and C. psittaci in the Crested Ibis, which may indicate a potential threat to the endangered birds and should be aware of the future protection practice.