RESUMO
BACKGROUND: The obligate intracellular bacterial family Chlamydiaceae comprises a number of different species that cause disease in various vertebrate hosts including humans. Chlamydia suis, primarily found in the gastrointestinal tract of pigs, is the only species of the Chlamydiaceae family to have naturally gained tetracycline resistance (TetR), through a genomic island (Tet-island), integrated into the middle of chromosomal invasin-like gene inv. Previous studies have hypothesised that the uptake of the Tet-island from a host outside the Chlamydiaceae family was a unique event, followed by spread among C. suis through homologous recombination. In vitro recombination studies have shown that Tet-island exchange between C. suis strains is possible. Our aim in this study was to gain a deeper understanding of the interclade recombination of the Tet-island, among currently circulating C. suis field strains compared to in vitro-generated recombinants, using published whole genome sequences of C. suis field strains (n = 35) and in vitro-generated recombinants (n = 63). RESULTS: We found that the phylogeny of inv better reflected the phylogeny of the Tet-island than that of the whole genome, supporting recombination rather than site-specific insertion as the means of transfer. There were considerable differences between the distribution of recombinations within in vitro-generated strains compared to that within the field strains. These differences are likely because in vitro-generated recombinants were selected for a tetracycline and rifamycin/rifampicin resistant background, leading to the largest peak of recombination across the Tet-island. Finally, we found that interclade recombinations across the Tet-island were more variable in length downstream of the Tet-island than upstream. CONCLUSIONS: Our study supports the hypothesis that the occurrence of TetR strains in both clades of C. suis came about through interclade recombination after a single ancestral horizontal gene transfer event.
Assuntos
Chlamydia , Ilhas Genômicas , Filogenia , Recombinação Genética , Resistência a Tetraciclina , Chlamydia/genética , Resistência a Tetraciclina/genética , Animais , Suínos , Transferência Genética Horizontal , Genoma BacterianoRESUMO
This study reports gross, histopathological, and molecular features of a Chlamydia abortus infection in a stranded female striped dolphin Stenella coeruleoalba from the Tyrrhenian coast of southern Italy. Post-mortem examination revealed liver congestion, splenic lymphoid depletion with capsular petechiae, and pneumonia. Histology revealed disseminated intravascular coagulation with vasculitis and congestion. Hepatocellular and acute myocardial degeneration were also observed. Basophilic, coccobacillary inclusions consistent with Chlamydia spp. were observed histologically in the type II pneumocytes, myocardial fibers, and hepatocytes, and in macrophages and plasma cells of liver, spleen, and prescapular lymph nodes. Chlamydial antigen was detected by immunofluorescence assay using genus-specific anti-Chlamydia antibodies. PCR assay revealed C. abortus in spleen, liver, heart, and lungs. C. abortus was the only pathogen detected. The main pathological changes suggest that Chlamydia infection may have been the cause of stranding and death of the striped dolphin. This case represents the first molecular detection of a member of the Chlamydiaceae in a marine mammal.
Assuntos
Chlamydia , Stenella , Animais , Feminino , ItáliaRESUMO
Chlamydiae have a worldwide distribution causing a wide range of diseases in human hosts, livestock, and companion animals as well as in wildlife and exotic species. Moreover, they can persist in their hosts as asymptomatic infections for extended periods of time. The introduction of molecular techniques has revolutionized the Chlamydia field by expanding the host range of known chlamydial species but also by discovering new species and even new families of bacteria in the broader order Chlamydiales. The wide range of hosts, diseases, and tissues affected by chlamydiae complicate the diagnosis such that standard diagnostic approaches for these bacteria are rare. Bacteria of the Chlamydiales order are small and their inclusions are difficult to detect by standard microscopy. With the exception of avian and ovine chlamydiosis, macroscopic and/or histologic changes might not be pathognomic or indicative for a chlamydial infection or even not present at all. Moreover, detection of chlamydial DNA in specimens in the absence of other methods or related pathological lesions questions the significance of such findings. The pathogenic potential of the majority of recently identified Chlamydia-related bacteria remains largely unknown and awaits investigation through experimental or natural infection models including histomorphological characterization of associated lesions. This review aims to summarize the historical background and the most important developments in the field of animal chlamydial research in the past 5 years with a special focus on pathology. It will summarize the current nomenclature, present critical thoughts about diagnostics, and give an update on chlamydial infections in domesticated animals such as livestock, companion animals and birds, as well as free-ranging and captive wild animals such as reptiles, fish, and marsupials.
Assuntos
Animais Selvagens/microbiologia , Infecções por Chlamydia/veterinária , Chlamydiales , Gado/microbiologia , Animais de Estimação/microbiologia , Animais , Infecções por Chlamydia/diagnóstico , Infecções por Chlamydia/patologiaRESUMO
Chlamydiaceae bacteria infect many vertebrate hosts, and previous reports based on polymerase chain reaction (PCR) assays and serologic assays that are prone to cross-reaction among chlamydial organisms have been used to describe the prevalence of either DNA fragments or antibodies to Chlamydia spp. in wild raptorial populations. This study reports the PCR-based prevalence of Chlamydiaceae DNA that does not 100% match any avian or mammalian Chlamydiaceae in wild populations of hawks in California Buteo species. In this study, multimucosal swab samples ( n = 291) for quantitative PCR (qPCR) and plasma ( n = 78) for serology were collected from wild hawks. All available plasma samples were negative for antibodies using a C. psittaci-specific elementary body agglutination test (EBA; n = 78). For IgY antibodies all 51 available samples were negative using the indirect immunofluorescent assay. The overall prevalence of Chlamydiaceae DNA detection in wild Buteo species sampled was 1.37% (4/291) via qPCR-based analysis. Two fledgling Swainson's hawks ( Buteo swainsoni) and two juvenile red-tailed hawks ( Buteo jamaicensis) were positive by qPCR-based assay for an atypical chlamydial sequence that did not 100% match any known C. psittaci genotype. Positive swab samples from these four birds were sequenced based on the ompA gene and compared by high-resolution melt analysis with all known avian and mammalian Chlamydiaceae. The amplicon sequence did not 100% match any known avian chlamydial sequence; however, it was most similar (98.6%) to C. psittaci M56, a genotype that is typically found in muskrats and hares. Culture and full genome sequence analysis of Chlamydia spp. isolated from diseased hawks will be necessary to classify this organism and to better understand its epizootiology and potential health impact on wild Buteo populations in California.
Assuntos
Doenças das Aves/microbiologia , Infecções por Chlamydiaceae/veterinária , Chlamydiaceae/isolamento & purificação , Falcões/microbiologia , Animais , Doenças das Aves/epidemiologia , California/epidemiologia , Infecções por Chlamydiaceae/epidemiologia , Infecções por Chlamydiaceae/microbiologia , Estudos SoroepidemiológicosRESUMO
Reproductive losses linked to an infectious etiology in bovine cattle are a major economic concern worldwide. In Argentina, more than 50% of abortion cases have unknown causes. Species belonging to Chlamydiaceae family are frequent etiologic agents of abortion around the world; however, there is yet no information on their prevalence in Argentina. The objective of this work was to identify Chlamydia spp., and particularly C. abortus in reproductive losses from bovine cattle in La Pampa, Argentina. Real time PCR targeting Chlamydiaceae-specific DNA fragments was performed on 251 samples obtained from bovine abortions and stillborns, and ArrayTube was used for species identification on positive samples. Chlamydiaceae DNA was detected in 12 samples of aborted fetuses (4.78%), 83.33% (10/12) accounting for abortions and 16.66% (2/12) for stillborns. C. abortus was detected by ArrayTube in 5 cases (1.99% of all samples, and 41.67% of Chlamydiaceae positive samples). This study shows the first detection of Chlamydiaceae and C. abortus DNA on reproductive losses of bovine cattle in Argentina, and the described prevalence value (4.78%) should be taken as baseline value due to the type of samples analyzed. Detection of genetic material from Chlamydiaceae not matching any of the studied species could be due to intraspecies variants or local species not yet described. Further research on Chlamydia infections in bovine cattle in Argentina is imperative to describe their range, to analyze their economic and zoonotic implications and to make recommendations about prevention and control measures.
Assuntos
Doenças dos Bovinos , Infecções por Chlamydia , Chlamydia , Animais , Argentina , Bovinos , Doenças dos Bovinos/diagnóstico , Chlamydia/isolamento & purificação , Infecções por Chlamydia/diagnóstico , Infecções por Chlamydia/veterinária , Feminino , Gravidez , ReproduçãoRESUMO
Background: Amoebic keratitis is a potentially blinding eye infection caused by ubiquitous, free-living, environmental acanthamoebae, which are known to harbor bacterial endosymbionts. A Chlamydia-like endosymbiont has previously enhanced Acanthamoeba virulence in vitro. We investigated the potential effect of Acanthamoeba-endosymbiont coinfection in a human corneal tissue model representing clinical amoebic keratitis infection. Methods: Environmental and corneal Acanthamoeba isolates from the American Type Culture Collection were screened for endosymbionts by amplifying and sequencing bacterial 16S as well as Chlamydiales-specific DNA. Each Acanthamoeba isolate was used to infect EpiCorneal cells, a 3-dimensional human corneal tissue model. EpiCorneal cells were then treated with azithromycin, doxycycline, or control medium to determine whether antibiotics targeting common classes of bacterial endosymbionts attenuated Acanthamoeba virulence, as indicated by decreased observed cytopathic effect and inflammatory biomarker production. Results: A novel endosymbiont closely related to Mycobacterium spp. was identified in Acanthamoeba polyphaga 50495. Infection of EpiCorneal cells with Acanthamoeba castellanii 50493 and A. polyphaga 50372 led to increased production of inflammatory cytokines and cytopathic effects visible under microscopy. These increases were attenuated by azithromycin and doxycycline. Conclusions: Our findings suggest that azithromycin and doxycycline may be effective adjuvants to standard antiacanthamoebal chemotherapy by potentially abrogating virulence-enhancing properties of bacterial endosymbionts.
Assuntos
Acanthamoeba/patogenicidade , Azitromicina/farmacologia , Chlamydiaceae/efeitos dos fármacos , Córnea/parasitologia , Doxiciclina/farmacologia , Ceratite/parasitologia , Amebíase/tratamento farmacológico , Biomarcadores/análise , Células Cultivadas , Chlamydiaceae/genética , Córnea/patologia , Citocinas/metabolismo , Humanos , RNA Ribossômico 16S/genética , Simbiose/efeitos dos fármacos , Virulência/efeitos dos fármacosRESUMO
From 2003 to 2015, 360 free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL, n = 246), Florida, and coastal waters of Charleston (CHS, n = 114), South Carolina, USA, were captured, given comprehensive health examinations, and released as part of a multidisciplinary and multi-institutional study of individual and population health. The aim of this review is to summarize the substantial health data generated by this study and to examine morbidity between capture sites and over time. The IRL and CHS dolphin populations are affected by complex infectious and neoplastic diseases often associated with immunologic disturbances. We found evidence of infection with cetacean morbillivirus, dolphin papilloma and herpes viruses, Chlamydiaceae, a novel uncultivated strain of Paracoccidioides brasiliensis (recently identified as the causal agent of dolphin lobomycosis/lacaziasis), and other pathogens. This is the first long-term study documenting the various types, progression, seroprevalence, and pathologic interrelationships of infectious diseases in dolphins from the southeastern USA. Additionally, the study has demonstrated that the bottlenose dolphin is a valuable sentinel animal that may reflect environmental health concerns and parallel emerging public health issues.
Assuntos
Golfinho Nariz-de-Garrafa , Doenças Transmissíveis/veterinária , Monitoramento Ambiental , Animais , Doenças Transmissíveis/epidemiologia , Medição de Risco , Sudeste dos Estados Unidos/epidemiologiaRESUMO
Chlamydiaceae is a family of intracellular bacteria causing a range of diverse pathological outcomes. The most devastating human diseases are ocular infections with C. trachomatis leading to blindness and genital infections causing pelvic inflammatory disease with long-term sequelae including infertility and chronic pelvic pain. In order to enable the comparison of experiments between laboratories investigating host-chlamydia interactions, the infectious titer has to be determined. Titer determination of chlamydia is most commonly performed via microscopy of host cells infected with a serial dilution of chlamydia. However, other methods including fluorescent ELISpot (Fluorospot) and DNA Chip Scanning Technology have also been proposed to enumerate chlamydia-infected cells. For viruses, flow cytometry has been suggested as a superior alternative to standard titration methods. In this study we compared the use of flow cytometry with microscopy and Fluorospot for the titration of C. suis as a representative of other intracellular bacteria. Titer determination via Fluorospot was unreliable, while titration via microscopy led to a linear read-out range of 16 - 64 dilutions and moderate reproducibility with acceptable standard deviations within and between investigators. In contrast, flow cytometry had a vast linear read-out range of 1,024 dilutions and the lowest standard deviations given a basic training in these methods. In addition, flow cytometry was faster and material costs were lower compared to microscopy. Flow cytometry offers a fast, cheap, precise, and reproducible alternative for the titration of intracellular bacteria like C. suis. © 2016 International Society for Advancement of Cytometry.
Assuntos
Chlamydiaceae/isolamento & purificação , Células Epiteliais/microbiologia , Citometria de Fluxo/métodos , Linhagem Celular , Humanos , Microscopia , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Avian chlamydiosis is a bacterial infectious disease of birds, considered until recently caused only by Chlamydia psittaci, that now includes the newly described species C. buteonis, C. avium, and C. gallinacea, associated with several avian hosts. Since its recognition as a species in 2014 and having chickens as one of its main hosts, C. gallinacea has already been described in backyard poultry on all continents. The present study aimed to survey by molecular techniques the presence and species of Chlamydia spp. in backyard chickens from three states of the southern region of Brazil (Paraná-PR, Santa Catarina-SC, and Rio Grande do Sul-RS). DNA extracted from cloacal swab samples were tested by polymerase chain reaction (PCR) for different species of Chlamydia, namely Chlamydiaceae (23 S rRNA gene), C. psittaci (ompA gene), C. avium (enoA gene) and C. gallinacea (gidA and enoA genes). The 16 S rRNA gene was used for sequencing and phylogenetic analysis. A total of 582 backyard chicken samples were collected and grouped in 238 pools, from 134 properties in 59 municipalities. Chlamydiaceae was detected in 25.2% (60/238) of the samples, in 38.8% (52/134) of the properties and in 66.1% (39/59) of the municipalities. None of the samples yielded positive PCR results for C. psittaci or C. avium. For C. gallinacea, the overall percentage was 16.3% (39/238) according to the results of gidA and enoA genes. Sequence analysis confirmed that the samples corresponded to C. gallinacea. This is the first report of C. gallinacea in Brazil.
Assuntos
Galinhas , Infecções por Chlamydia , Chlamydia , Filogenia , Doenças das Aves Domésticas , Animais , Galinhas/microbiologia , Brasil , Chlamydia/genética , Chlamydia/classificação , Chlamydia/isolamento & purificação , Infecções por Chlamydia/veterinária , Infecções por Chlamydia/microbiologia , Doenças das Aves Domésticas/microbiologia , Doenças das Aves Domésticas/epidemiologia , Fazendas , RNA Ribossômico 16S/genética , DNA Bacteriano/genéticaRESUMO
Chlamydiaceae are a family of obligate intracellular bacterial pathogens that affect both humans and animals. Recently, a new species named Chlamydia (C.) buteonis was isolated from hawks. In this study, we aimed to investigate the prevalence of Chlamydiaceae in 60 falcons that underwent a routine health check at a specialized clinic in Dubai, United Arab Emirates. Using real-time PCR, we analyzed cloacal and tracheal swabs from these birds and found that 39 of them tested positive for Chlamydiaceae. Subsequent real-time PCR assays specific for C. psittaci, C. abortus, C. avium, and C. gallinacea yielded negative results, while testing positive for C. buteonis. Analysis of ompA and MLST sequences indicated a highly conserved group of strains within this set of samples, but with sequences distinct from the C. buteonis RSHA reference strains and other C. buteonis strains isolated from hawks in the United States. Two strains were further isolated by cell culture and sequenced using whole-genome sequencing, confirming the clustering of these falcon strains within the C. buteonis species, but in a separate clade from the previously identified hawk strains. We also developed a SNP-based PCR-HRM assay to distinguish between these different genotypes. Overall, our findings suggest a high prevalence of C. buteonis in falcons in Dubai and highlight the importance of monitoring this pathogen in birds of prey.
Assuntos
Chlamydia , Chlamydiaceae , Falconiformes , Humanos , Animais , Tipagem de Sequências Multilocus/veterinária , Chlamydia/genética , Aves/microbiologia , GenótipoRESUMO
Trachoma is the leading cause of preventable blindness. Commercial assays do not discriminate among all Chlamydiaceae species that might be involved in trachoma. We investigated whether a commercial Micro-ArrayTube could discriminate Chlamydiaceae species in DNA extracted directly from conjunctival samples from 101 trachoma patients in Nepal. To evaluate organism viability, we extracted RNA, reverse transcribed it, and subjected it to quantitative real-time PCR. We found that 71 (70.3%) villagers were infected. ArrayTube sensitivity was 91.7% and specificity was 100% compared with that of real-time PCR. Concordance between genotypes detected by microarray and ompA genotyping was 100%. Species distribution included 54 (76%) single infections with Chlamydia trachomatis, C. psittaci, C. suis, or C. pecorum, and 17 (24%) mixed infections that includied C. pneumoniae. Ocular infections were caused by 5 Chlamydiaceae species. Additional studies of trachoma pathogenesis involving Chlamydiaceae species other than C. trachomatis and their zoonotic origins are needed.
Assuntos
Chlamydiaceae/classificação , Tracoma/epidemiologia , Tracoma/transmissão , Adolescente , Proteínas da Membrana Bacteriana Externa/genética , Criança , Pré-Escolar , Chlamydia trachomatis/genética , Chlamydiaceae/genética , Feminino , Genótipo , Humanos , Lactente , Masculino , Nepal/epidemiologiaRESUMO
Galápagos Penguin (Spheniscus mendiculus), Flightless Cormorant (Phalacrocorax harrisi), and Waved Albatross (Phoebastria irrorata) are among the most vulnerable species to natural and anthropogenic factors in the Galápagos Islands. In 2017, a dedicated study was conducted to detect Chlamydiaceae on cloacal swabs collected from 59 albatrosses, 68 penguins, and 10 cormorants in different islands and sites in the Galápagos Archipelago. A real-time PCR method targeting the conserved 23S ribosomal RNA gene of the Chlamydiaceae family detected the presence of the bacterium only in albatrosses from Punta Suárez, Española Island, with 21 positive samples (35.6%), whereas negative results were obtained with available real-time PCR systems specific to Chlamydia psittaci and Chlamydia abortus. Multilocus sequence typing (MLST) of the most strongly positive samples revealed a new sequence type closely related to the recently described avian strains of C. abortus. For a quick identification, a new real-time PCR system that allows the detection of all strains (avian and ruminant) belonging to the C. abortus species has been developed. Applied to a second set of samples from 31 albatrosses collected at Punta Suárez, Española Island, in 2018, the new real-time PCR system confirmed the presence of this bacteria in this group of birds, with the same new MLST sequence type.
Assuntos
Chlamydia , Chlamydiaceae , Spheniscidae , Animais , Tipagem de Sequências Multilocus/veterinária , Chlamydia/genética , Chlamydiaceae/genética , RuminantesRESUMO
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.
Assuntos
Amazona , Doenças das Aves , Chlamydia , Papagaios , Psitacose , Animais , Amazona/microbiologia , Argentina , Doenças das Aves/microbiologia , Psitacose/epidemiologia , Psitacose/microbiologia , Psitacose/veterináriaRESUMO
INTRODUCTION: Knowledge of the obligate intracellular bacteria from the Chlamydiaceae family has increased significantly in recent years. Not only new chlamydia species, such as Chlamydia avium or C. buteonis in birds have been described, but also known chlamydia in new host species, such as C. psittaci in horses. This review article provides an up-to-date overview of the zoonotic potential of C. psittaci, C. abortus, C. caviae and C. felis and summarizes current findings on other chlamydia species in different animal species; supplemented by information on optimal sampling and pathogen detection.
INTRODUCTION: Les connaissances sur les bactéries intracellulaires obligatoires de la famille des Chlamydiaceae ont considérablement augmenté ces dernières années. Non seulement de nouvelles espèces de Chlamydies, telles que Chlamydia avium ou C. buteonis chez les oiseaux, ont été décrites, mais également des Chlamydies déjà connues ont été mises en évidence chez de nouvelles espèces hôtes, telles que C. psittaci chez les chevaux. Cet article de synthèse fournit une vue d'ensemble actualisée du potentiel zoonotique de C. psittaci, C. abortus, C. caviae et C. felis et résume les connaissances actuelles sur d'autres espèces de Chlamydies chez différentes espèces animales ; il est complété par des informations sur l'échantillonnage optimal et la détection des agents pathogènes.
Assuntos
Chlamydia , Zoonoses , Animais , Cavalos , Zoonoses/microbiologiaRESUMO
IMPORTANCE: The obligate intracellular Chlamydia genus contains many pathogens with a negative impact on global health and economy. Despite recent progress, there is still a lack of genetic tools limiting our understanding of these complex bacteria. This study provides new insights into genetic manipulation of Chlamydia with the opportunistic porcine pathogen Chlamydia suis, the only chlamydial species naturally harboring an antibiotic resistance gene, originally obtained by horizontal gene transfer. C. suis is transmissible to humans, posing a potential public health concern. We report that C. suis can take up vectors that lack the native plasmid, a requirement for most chlamydial transformation systems described to date. Additionally, we show that C. trachomatis, the most common cause for bacterial sexually transmitted infections and infectious blindness worldwide, can be transformed with C. suis vectors. Finally, the chromosomal region that harbors the resistance gene of C. suis is highly susceptible to complete vector integration.
Assuntos
Infecções por Chlamydia , Chlamydia , Animais , Humanos , Suínos , Chlamydia/genética , Chlamydia trachomatis , Infecções por Chlamydia/microbiologia , Antibacterianos , Vetores GenéticosRESUMO
The genus Chlamydia contains important obligate intracellular bacterial pathogens to humans and animals, including C. trachomatis and C. pneumoniae. Since 1998, when the first Chlamydia genome was published, our understanding of how these microbes interact, evolved and adapted to different intracellular host environments has been transformed due to the expansion of chlamydial genomes. This review explores the current state of knowledge in Chlamydia genomics and how whole genome sequencing has revolutionised our understanding of Chlamydia virulence, evolution, and phylogeny over the past two and a half decades. This review will also highlight developments in multi-omics and other approaches that have complemented whole genome sequencing to advance knowledge of Chlamydia pathogenesis and future directions for chlamydial genomics.
Assuntos
Infecções por Chlamydia , Chlamydia , Animais , Humanos , Filogenia , Virulência/genética , Chlamydia/genética , Chlamydia trachomatis/genética , Infecções por Chlamydia/microbiologia , Genômica , Sequenciamento Completo do Genoma , Genoma BacterianoRESUMO
Lateral gene transfer (LGT) facilitates many processes in bacterial ecology and pathogenesis, especially regarding pathogen evolution and the spread of antibiotic resistance across species. The obligate intracellular chlamydiae, which cause a range of diseases in humans and animals, were historically thought to be highly deficient in this process. However, research over the past few decades has demonstrated that this was not the case. The first reports of homologous recombination in the Chlamydiaceae family were published in the early 1990s. Later, the advent of whole-genome sequencing uncovered clear evidence for LGT in the evolution of the Chlamydiaceae, although the acquisition of tetracycline resistance in Chlamydia (C.) suis is the only recent instance of interphylum LGT. In contrast, genome and in vitro studies have shown that intraspecies DNA exchange occurs frequently and can even cross species barriers between closely related chlamydiae, such as between C. trachomatis, C. muridarum, and C. suis. Additionally, whole-genome analysis led to the identification of various DNA repair and recombination systems in C. trachomatis, but the exact machinery of DNA uptake and homologous recombination in the chlamydiae has yet to be fully elucidated. Here, we reviewed the current state of knowledge concerning LGT in Chlamydia by focusing on the effect of homologous recombination on the chlamydial genome, the recombination machinery, and its potential as a genetic tool for Chlamydia.
Assuntos
Chlamydia , Transferência Genética Horizontal , Animais , Chlamydia/genética , Chlamydia trachomatis/genética , Resistência a Tetraciclina/genéticaRESUMO
Chlamydiaceae are obligatory intracellular bacteria causing acute and chronic diseases in animals and humans worldwide, with recently discovered species with a still unclear pathogenic potential (i.e., C. gallinacea). In Italy, Chlamydiaceae infections are underestimated both in animals and humans. To estimate the prevalence of Chlamydiaceae species in poultry and occupationally exposed workers on farm, a cross-sectional study was carried out in north-western Italy. A total of 2063 samples from 83 commercial and 31 backyard poultry farms were analysed using real-time PCRs for Chlamydiaceae screening and species typing. Chlamydiaceae were detected in 23 farms, with a herd prevalence of 20.2% (95%CI: 13.2-28.7), higher in backyard farms (38.7%; 95%CI: 21.8-57.8) compared to commercial ones (13.3%; 95%CI: 6.8-22.5). C. gallinacea was found in 18 chicken farms, both commercial and backyard, and C. psittaci only in 3 backyard farms. Exposure to wild birds and factors related to biosecurity resulted the main risk factors associated with Chlamydia positivity. Out of the 113 sputum samples collected from farmers, 16 tested positive to Chlamydiaceae, with a prevalence of 14.2% (95%CI: 8, 3-22). To the best of our knowledge, for the first time at international level, C. gallinacea was detected in humans with farmer positivity associated with farm infectious status, suggesting a bird-to-human transmission.
Assuntos
Infecções por Chlamydia , Chlamydia , Doenças das Aves Domésticas , Animais , Galinhas/microbiologia , Infecções por Chlamydia/epidemiologia , Estudos Transversais , Humanos , Aves Domésticas , Doenças das Aves Domésticas/microbiologia , Fatores de RiscoRESUMO
The Chlamydiaceae are a family of obligate intracellular, gram-negative bacteria known to readily exchange DNA by homologous recombination upon co-culture in vitro, allowing the transfer of antibiotic resistance residing on the chlamydial chromosome. Among all the obligate intracellular bacteria, only Chlamydia (C.) suis naturally integrated a tetracycline resistance gene into its chromosome. Therefore, in order to further investigate the readiness of Chlamydia to exchange DNA and especially antibiotic resistance, C. suis is an excellent model to advance existing co-culture protocols allowing the identification of factors crucial to promote homologous recombination in vitro. With this strategy, we co-cultured tetracycline-resistant with rifamycin group-resistant C. suis, which resulted in an allover recombination efficiency of 28%. We found that simultaneous selection is crucial to increase the number of recombinants, that sub-inhibitory concentrations of tetracycline inhibit rather than promote the selection of double-resistant recombinants, and identified a recombination-deficient C. suis field isolate, strain SWA-110 (1-28b). While tetracycline resistance was detected in field isolates, rifampicin/rifamycin resistance (RifR) had to be induced in vitro. Here, we describe the protocol with which RifR C. suis strains were generated and confirmed. Subsequent whole-genome sequencing then revealed that G530E and D461A mutations in rpoB, a gene encoding for the ß-subunit of the bacterial RNA polymerase (RNAP), was likely responsible for rifampicin and rifamycin resistance, respectively. Finally, whole-genome sequencing of recombinants obtained by co-culture revealed that recombinants picked from the same plate may be sibling clones and confirmed C. suis genome plasticity by revealing variable, apparently non-specific areas of recombination.
RESUMO
Chlamydia (C.) caviae is a known pathogen in guinea pigs, causing conjunctivitis, respiratory infections and abortions. Recently, a C. caviae-induced zoonotic link was identified as the etiology of severe community-acquired pneumonia in humans. Here, 784 conjunctival and rectal swabs originating from 260 guinea pigs and 110 rabbits from 64 husbandries in Switzerland, as well as 200 composite conjunctival swabs originating from 878 guinea pigs from 37 husbandries in The Netherlands were examined by real-time PCR followed by conventional PCR and sequencing. Chlamydiaceae were detected in 2.3% (18/784) and 12.5% (25/200) of all Swiss and Dutch samples, respectively. An overall C. caviae occurrence was detected in 2.7% (7/260) and 8.9% (78/878) of all Swiss and Dutch guinea pigs, respectively. OmpA genotyping of 64 C. caviae-positive samples resulted in 33 sequences sharing 100% nucleotide identity with the strains isolated from the zoonotic transmission cases in The Netherlands. However, all ompA sequences of this study were distinct from the C. caviae GPIC reference strain. C. caviae was not detected in rabbits but C. psittaci genotype A was identified in guinea pigs and rabbits, raising concerns about the importance of these animal species as novel zoonotic sources for C. psittaci.