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obligate intracellular bacterial parasites of acanthamoebae related to chlamydia spp.the phylogeny of obligate intracellular coccoid parasites of acanthamoebae isolated from the nasal mucosa of humans was analyzed by the rrna approach. the primary structures of the 16s and 23s rrna molecules of one strain were determined in almost full length. in situ hybridization with a horseradish peroxidase-labeled oligonucleotide probe targeted to a unique signature site undoubtedly correlated the retrieved 16s rrna sequence to the respective intracellular parasite. this probe also hybridiz ...19978979345
emended description of the order chlamydiales, proposal of parachlamydiaceae fam. nov. and simkaniaceae fam. nov., each containing one monotypic genus, revised taxonomy of the family chlamydiaceae, including a new genus and five new species, and standards for the identification of organisms.the current taxonomic classification of chlamydia is based on limited phenotypic, morphologic and genetic criteria. this classification does not take into account recent analysis of the ribosomal operon or recently identified obligately intracellular organisms that have a chlamydia-like developmental cycle of replication. neither does it provide a systematic rationale for identifying new strains. in this study, phylogenetic analyses of the 16s and 23s rrna genes are presented with corroborating ...199910319462
an unspliced group i intron in 23s rrna links chlamydiales, chloroplasts, and mitochondria.chlamydia was the only genus in the order chlamydiales until the recent characterization of simkania negevensis z(t) and parachlamydia acanthamoebae strains. the present study of chlamydiales 23s ribosomal dna (rdna) focuses on a naturally occurring group i intron in the i-cpai target site of 23s rdna from s. negevensis. the intron, snlsu. 1, belonged to the ib4 structural subgroup and was most closely related to large ribosomal subunit introns that express single-motif, laglidadg endonucleases ...199910438738
characterization of the rnpb gene and rnase p rna in the order chlamydiales.the sequence of the rnase p rna gene (rnpb) was determined for 60 strains representing all nine species in the family chlamydiaceae and for the related chlamydiales species, parachlamydia acanthamoebae and simkania negevensis. these sequences were used to infer evolutionary relationships among the chlamydiaceae. the analysis separated chlamydophila and chlamydia into two lineages, with chlamydophila forming three distinct clusters: the chlamydophila pneumoniae strains; the chlamydophila pecorum ...200010826799
phylogenetic diversity among geographically dispersed chlamydiales endosymbionts recovered from clinical and environmental isolates of acanthamoeba spp.the recently proposed reorganization of the order chlamydiales and description of new taxa are broadening our perception of this once narrowly defined taxon. we have recovered four strains of gram-negative cocci endosymbiotic in acanthamoeba spp., representing 5% of the acanthamoeba sp. isolates examined, which displayed developmental life cycles typical of members of the chlamydiales. one of these endosymbiont strains was found stably infecting an amoebic isolate recovered from a case of amoebi ...200010831445
parachlamydiaceae: potential emerging pathogens.parachlamydiaceae, which naturally infect amoebae, form a sister taxon to the chlamydiaceae on the basis of the chlamydia-like cycle of replication and 80% to 90% homology of ribosomal rna genes. because intra-amoebal growth could increase the virulence of some intracellular bacteria, parachlamydiaceae may be pathogenic. arguments supporting a pathogenic role are that chlamydia pneumoniae, a well-recognized agent of pneumonia, was shown to infect free-living amoebae and that another member of th ...200212023921
new parachlamydial 16s rdna phylotypes detected in human clinical samples.chlamydiales are important intracellular bacterial pathogens, causing a wide variety of diseases in vertebrates, including humans. besides the well-known species in the family chlamydiaceae, new chlamydial organisms have recently been discovered, forming three new families: parachlamydiaceae, simkaniaceae and waddliaceae. parachlamydia acanthamoebae and simkania negevensis are currently investigated as emerging human respiratory pathogens. additional chlamydial lineages have been discovered by 1 ...200212455703
history of the adp/atp-translocase-encoding gene, a parasitism gene transferred from a chlamydiales ancestor to plants 1 billion years ago.nonmitochondrial adp/atp translocase is an energy parasite enzyme. its encoding gene, tlc, is found only in rickettsiales, chlamydiales, and plant and alga plastids. we demonstrate the presence of tlc in parachlamydia acanthamoebae. this gene shares more similarity with the tlc1 gene of chlamydiaceae and the tlc of plant and alga plastids than with the tlc2 gene of chlamydiaceae. phylogenetic analysis, including all other tlc homologs found in genbank, showed that tlc was duplicated in a chlamyd ...200312957942
parachlamydia acanthamoebae enters and multiplies within human macrophages and induces their apoptosis [corrected].parachlamydia acanthamoebae is an obligately intracellular bacterium that naturally infects free-living amoebae. it is a potential human pathogen and may survive in human macrophages. we studied p. acanthamoebae entry into, and multiplication within, human monocyte-derived macrophages. after 8 h of incubation, 80% of macrophages were infected with a mean of 3.8 p. acanthamoebae organisms per cell. electron microscopy demonstrated that parachlamydiae were in an intracellular vacuole. after infect ...200314500518
microorganisms resistant to free-living amoebae.free-living amoebae feed on bacteria, fungi, and algae. however, some microorganisms have evolved to become resistant to these protists. these amoeba-resistant microorganisms include established pathogens, such as cryptococcus neoformans, legionella spp., chlamydophila pneumoniae, mycobacterium avium, listeria monocytogenes, pseudomonas aeruginosa, and francisella tularensis, and emerging pathogens, such as bosea spp., simkania negevensis, parachlamydia acanthamoebae, and legionella-like amoebal ...200415084508
detection of mycobacteria and chlamydiae in granulomatous inflammation of reptiles: a retrospective study.a retrospective study on reptile tissues presenting with granulomatous inflammation was performed to detect the possible presence of mycobacteria and chlamydiae in these lesions. ninety cases including 48 snakes, 27 chelonians, and 15 lizards were selected. mycobacteria were detected by ziehl-neelsen (zn) staining and a broad-range polymerase chain reaction (pcr) followed by dna sequencing. to detect chlamydiae, immunohistochemistry with monoclonal antibodies against chlamydial lipopolysaccharid ...200415232139
emerging chlamydial infections.chlamydiae are important intracellular bacterial pathogens of vertebrates. in the last years, novel members of this group have been discovered: parachlamydia acanthamoebae and simkania negevensis seems to be emerging respiratory human pathogens, while waddlia chondrophila might be a new agent of bovine abortion. various species have been showed to infect also the herpetofauna and fishes, and some novel chlamydiae are endosymbionts of arthropods. in addition, molecular studies evidenced a huge di ...200415239381
recovery of an environmental chlamydia strain from activated sludge by co-cultivation with acanthamoeba sp.chlamydiae are a unique group of obligate intracellular bacteria comprising important pathogens of vertebrates as well as symbionts of free-living amoebae. although there is ample molecular evidence for a huge diversity and wide distribution of chlamydiae in nature, environmental chlamydiae are currently represented by only few isolates. this paper reports the recovery of a novel environmental chlamydia strain from activated sludge by co-cultivation with acanthamoeba sp. the recovered environmen ...200515632447
intracellular trafficking of parachlamydia acanthamoebae.parachlamydia acanthamoebae is an obligate intracellular bacterium that naturally infects free-living amoebae. it is a potential agent of pneumonia that resists destruction by human macrophages. however, the strategy used by this chlamydia-like organism in order to resist to macrophage destruction is unknown. we analysed the intracellular trafficking of p. acanthamoebae within monocyte-derived macrophages. infected cells were immunolabelled for the bacteria and for various intracellular compartm ...200515760458
lack of microbicidal response in human macrophages infected with parachlamydia acanthamoebae.parachlamydia acanthamoebae is an obligate intracellular bacterium naturally infecting free-living amoebae. this potential agent of pneumonia resists destruction by human macrophages, inducing their death by apoptosis. however, the strategy used by parachlamydia to escape the microbicidal effectors of macrophages remains unknown. in this work, we defined the effect of parachlamydia on the cytokine secretion (measured in culture supernatants by immunoassays), on the oxidative burst (measured usin ...200515826869
'candidatus protochlamydia amoebophila', an endosymbiont of acanthamoeba spp.the obligately intracellular coccoid bacterium uwe25, a symbiont of acanthamoeba spp., was previously identified as being related to chlamydiae based upon the presence of a chlamydia-like developmental cycle and its 16s rrna gene sequence. analysis of its complete genome sequence demonstrated that uwe25 shows many characteristic features of chlamydiae, including dependency on host-derived metabolites, composition of the cell envelope and the ability to thrive as an energy parasite within the cel ...200516166679
pathogenic potential of novel chlamydiae and diagnostic approaches to infections due to these obligate intracellular bacteria.novel chlamydiae are newly recognized members of the phylum chlamydiales that are only distantly related to the classic chlamydiaceae, i.e., chlamydia and chlamydophila species. they also exhibit an obligate biphasic intracellular life cycle within eukaryote host cells. some of these new chlamydiae are currently considered potential emerging human and/or animal pathogens. parachlamydia acanthamoebae and simkania negevensis are both emerging respiratory human pathogens, waddlia chondrophila could ...200616614250
chlamydiales in guinea-pigs and their zoonotic potential.the aim was to detect and characterize chlamydial infections in guinea-pigs (gp) with ocular disease, study their pathogenicity and zoonotic potential and to test for the presence of acanthamoebae spp. in gp eyes and to investigate whether they could act as vectors for chlamydia-like organisms. overall 126 gp, of which 77 were symptomatic, were screened by clinical examination, cytology, gross pathology, histology, immunohistochemistry, polymerase chain reaction (pcr) and bacteriology. a new chl ...200616629952
parachlamydia acanthamoebae enters and multiplies within pneumocytes and lung fibroblasts.parachlamydia acanthamoebae is a chlamydia-like organism that naturally infects free-living amoebae. p. acanthamoebae is a putative emerging agent of community-acquired and inhalation pneumonia that may enter and multiply within human macrophages. however, since parachlamydia induces their apoptosis, macrophages may not represent a perennial niche for this obligate intracellular bacterium. therefore, we investigated whether pneumocytes and lung fibroblasts are permissive to parachlamydia infecti ...200616697235
resistance of different chlamydia-like organisms to quinolones and mutations in the quinoline resistance-determining region of the dna gyrase a- and topoisomerase-encoding genes.parachlamydia acanthamoebae has been shown to be resistant to fluoroquinolones. in this study, we determined the susceptibility of neochlamydia hartmannellae and simkania negevensis to quinolones using amoebal co-culture in the presence of serial dilutions of ciprofloxacin. the gyra and parc quinoline resistance-determining regions (qrdrs) were amplified and sequenced, and amino acid substitutions that may explain the observed quinolone resistance were investigated. neochlamydia and simkania wer ...200616697560
criblamydia sequanensis, a new intracellular chlamydiales isolated from seine river water using amoebal co-culture.accumulating evidence supports a role for chlamydia-related organisms as emerging pathogens for human and animals. assessment of their pathogenicity requires strain availability, at least for animal models and serological studies. as these obligate intracellular species are able to grow inside amoebae, we used co-culture with acanthamoeba castellanii in an attempt to recover new chlamydia-related species from river water. we isolated two strains from eight water samples. the first strain is a ne ...200617107554
emerging role of chlamydia and chlamydia-like organisms in adverse pregnancy outcomes.this review considers the roles of chlamydia spp. and newly identified chlamydia-like organisms in miscarriage, stillbirths and preterm labour in both animals and humans.200818192789
new diagnostic real-time pcr for specific detection of parachlamydia acanthamoebae dna in clinical samples.given the low sensitivity of amoebal coculture, we developed a specific real-time pcr for the detection of parachlamydia. the analytical sensitivity was high, and the inter- and intrarun variabilities were low. when the pcr was applied to nasopharyngeal aspirates, it was positive for six patients with bronchiolitis. future studies should assess the role of parachlamydia in bronchiolitis.200818234873
parachlamydia spp. and related chlamydia-like organisms and bovine abortion.chlamydophila abortus and waddlia chondrophila cause abortion in ruminants. we investigated the role of parachlamydia acanthamoebae in bovine abortion. results of immunohistochemical analyses were positive in 30 (70%) of 43 placentas from which chlamydia-like dna was amplified, which supports the role of parachlamydia spp. in bovine abortion.200718258043
predator or prey? chlamydophila abortus infections of a free-living amoebae, acanthamoeba castellani 9gu.limited evidence exists to suggest that the ability to invade and escape protozoan host cell bactericidal activity extends to members of the chlamydiaceae, intracellular pathogens of humans and animals and evolutionary descendants of amoeba-resisting chlamydia-like organisms. pcr and microscopic analyses of chlamydophila abortus infections of acanthamoeba castellani revealed uptake of this chlamydial pathogen but, unlike the well-described inhabitant of a. castellani, parachlamydia acanthamoebae ...200818467146
murine model of pneumonia caused by parachlamydia acanthamoebae.the role of parachlamydia acanthamoebae as an agent of pneumonia is suggested by sero-epidemiological studies, molecular surveys and by the permissivity of macrophages, lung fibroblasts and pneumocytes to this obligate intracellular bacteria. we thus developed a murine model of pneumonia due to parachlamydia. mice were inoculated intratracheally with parachlamydia acanthamoebae. pneumonia-associated mortality was of 50% 5 days post-inoculation. lungs histopathology was characterized by purulent ...200818502092
biodiversity of amoebae and amoebae-resisting bacteria in a drinking water treatment plant.the complex ecology of free-living amoebae (fla) and their role in spreading pathogenic microorganisms through water systems have recently raised considerable interest. in this study, we investigated the presence of fla and amoebae-resisting bacteria (arb) at various stages of a drinking water plant fed with river water. we isolated various amoebal species from the river and from several points within the plant, mostly at early steps of water treatment. echinamoeba- and hartmannella-related amoe ...200818637950
novel parachlamydia acanthamoebae quantification method based on coculture with amoebae.parachlamydia acanthamoebae, belonging to the order chlamydiales, is an obligately intracellular bacterium that infects free-living amoebae and is a potential human pathogen. however, no method exists to accurately quantify viable bacterial numbers. we present a novel quantification method for p. acanthamoebae based on coculture with amoebae. p. acanthamoebae was cultured either with acanthamoeba spp. or with mammalian epithelial hep-2 or vero cells. the infection rate of p. acanthamoebae (amoeb ...200818757579
evidence for parachlamydia in bovine abortion.bovine abortion of unknown infectious aetiology still remains a major economic problem. in this study, we focused on a new possible abortigenic agent called parachlamydia acanthamoebae. retrospective samples (n=235) taken from late-term abortions in cattle were investigated by real-time diagnostic pcr for chlamydiaceae and parachlamydia spp., respectively. histological sections of cases positive by real-time pcr for any chlamydia-related agent were further examined by immunohistochemistry using ...200918951734
parachlamydia acanthamoebae infection and abortion in small ruminants. 200819046541
evidence of maternal-fetal transmission of parachlamydia acanthamoebae. 200919116071
parachlamydia acanthamoebae, an emerging agent of pneumonia.parachlamydia acanthamoebae is a chlamydia-like organism that easily grows within acanthamoeba spp. thus, it probably uses these widespread free-living amoebae as a replicative niche, a cosmopolite aquatic reservoir and a vector. a potential role of p. acanthamoebae as an agent of lower respiratory tract infection was initially suggested by its isolation within an acanthamoeba sp. recovered from the water of a humidifier during the investigation of an outbreak of fever. additional serological an ...200919220336
development of a real-time pcr for the specific detection of waddlia chondrophila in clinical samples.waddlia chondrophila is considered as an emerging human pathogen likely involved in miscarriage and lower respiratory tract infections. given the low sensitivity of cell culture to recover such an obligate intracellular bacteria, molecular-based diagnostic approaches are warranted. we thus developed a real-time pcr that amplifies waddlia chondrophila dna. specific primers and probe were selected to target the 16s rrna gene. the pcr specifically amplified w. chondrophila but did not amplify other ...200919727868
high throughput sequencing and proteomics to identify immunogenic proteins of a new pathogen: the dirty genome approach.with the availability of new generation sequencing technologies, bacterial genome projects have undergone a major boost. still, chromosome completion needs a costly and time-consuming gap closure, especially when containing highly repetitive elements. however, incomplete genome data may be sufficiently informative to derive the pursued information. for emerging pathogens, i.e. newly identified pathogens, lack of release of genome data during gap closure stage is clearly medically counterproducti ...200920037647
amoebal pathogens as emerging causal agents of pneumonia.abstract despite using modern microbiological diagnostic approaches, the aetiological agents of pneumonia remain unidentified in about 50% of cases. some bacteria that grow poorly or not at all in axenic media used in routine clinical bacteriology laboratory but which can develop inside amoebae may be the agents of these lower respiratory tract infections (rtis) of unexplained aetiology. such amoebae-resisting bacteria, which coevolved with amoebae to resist their microbicidal machinery, may hav ...200920113355
comparison of five commercial serological tests for the detection of anti-chlamydia trachomatis antibodies.screening for chlamydia trachomatis-specific antibodies is valuable in investigating recurrent miscarriage, tubal infertility and extrauterine pregnancy. we compared here the performance of immunofluorescence (if) to four other commercial tests in detecting igg antibodies directed against c. trachomatis: two enzyme-linked immunosorbent assays (elisas) using the major outer membrane protein (momp) as the antigen, commercialised respectively by medac and r-biopharm (rb), one elisa using the chlamy ...201020349260
proteomic aspects of parachlamydia acanthamoebae infection in acanthamoeba spp.the free-living but facultatively pathogenic amoebae of the genus acanthamoeba are frequently infected with bacterial endosymbionts that can have a profound influence on the physiology and viability of their host. parachlamydia acanthamoebae, a chlamydial endosymbiont in acanthamoebae, is known to be either symbiotic or lytic to its host, depending on the ambient conditions, for example, temperature. moreover, parachlamydiae can also inhibit the encystment process in acanthamoeba, an essential s ...201020485385
fastidious intracellular bacteria as causal agents of community-acquired pneumonia.intracellular bacteria are common causes of community-acquired pneumonia that grow poorly or not at all on standard culture media and do not respond to beta-lactam antibiotic therapy. apart from well-established agents of pneumonia such as legionella pneumophila, mycoplasma pneumoniae, chlamydia pneumoniae, chlamydia psittaci and coxiella burnetii, some new emerging pathogens have recently been recognized, mainly parachlamydia acanthamoebae and simkania negevensis, two chlamydia-related bacteria ...201020586563
parachlamydia acanthamoebae in domestic cats with and without corneal disease.corneal samples of cats with and without corneal diseases were screened with a pan-chlamydiales pcr and specific pcrs for parachlamydia, protochlamydia, chlamydophila felis, acanthamoeba and feline herpesviruses (fhv-1). several corneal samples tested positive for parachlamydia and related chlamydiales, indicating cat exposure to these intracellular bacteria.201020618801
impact of free-living amoebae on presence of parachlamydia acanthamoebae in the hospital environment and its survival in vitro without requirement for amoebae.parachlamydia acanthamoebae is an obligately intracellular bacterium that infects free-living amoebae and is a potential human pathogen in hospital-acquired pneumonia. we examined whether the presence of p. acanthamoebae is related to the presence of acanthamoeba in an actual hospital environment and assessed the in vitro survival of p. acanthamoebae. ninety smear samples were collected between november 2007 and march 2008 (trial 1, n = 52) and between october 2008 and february 2009 (trial 2, n ...201020631104
role of myd88 and toll-like receptors 2 and 4 in the sensing of parachlamydia acanthamoebae.parachlamydia acanthamoebae is a chlamydia-related organism whose pathogenic role in pneumonia is supported by serological and molecular clinical studies and an experimental mouse model of lung infection. toll-like receptors (tlrs) play a seminal role in sensing microbial products and initiating innate immune responses. the aim of this study was to investigate the roles of myd88, tlr2, and tlr4 in the interaction of parachlamydia with macrophages. here, we showed that parachlamydia entered bone- ...201020837714
host range of obligate intracellular bacterium parachlamydia acanthamoebae.the obligate intracellular bacterium parachlamydia acanthamoebae is a potential human pathogen, but the host range of the bacteria remains unknown. hence, the growth of p. acanthamoebae bn₉ in protozoa (tetrahymena, acanthamoeba, dictyostelium) and mammalian cells (hep-2, vero, thp-1, pma-stimulated thp-1, jurkat) was assessed using an aiu assay which had been previously established by the current authors. p. acanthamoebae grew in acanthamoeba but not in the other cell types. the growth was also ...201021155362
identification and characterization of the chlamydia trachomatis l2 s-adenosylmethionine transporter.abstract methylation is essential to the physiology of all cells, including the obligate intracellular bacterium chlamydia. nevertheless, the methylation cycle is under strong reductive evolutionary pressure in chlamydia. only parachlamydia acanthamoebae and waddlia chondrophila genome sequences harbor homologs to metk, encoding the s-adenosylmethionine (sam) synthetase required for synthesis of sam, and to sahh, which encodes the s-adenosylhomocysteine (sah) hydrolase required for detoxificatio ...201121558433
chlamydia-related bacteria in respiratory samples in finland.chlamydiarelated bacteria, new members of the order chlamydiales, are suggested to be associated with respiratory disease. we used real-time pcr to investigate the prevalence of parachlamydia acanthamoebae, protochlamydia spp., rhabdochlamydia spp., simkania negevensis and waddlia chondrophila in samples taken from patients with suspected respiratory tract infections. of the 531 samples analyzed, the subset of 136 samples contained 16 (11.8%) samples positive for rhabdochlamydia spp. dna. p. aca ...201121612765
unity in variety - the pan-genome of the chlamydiae.chlamydiae are evolutionarily well-separated bacteria that live exclusively within eukaryotic host cells. they include important human pathogens such as chlamydia trachomatis as well as symbionts of protozoa. as these bacteria are experimentally challenging and genetically intractable, our knowledge about them is still limited. in this study, we obtained the genome sequences of simkania negevensis z, waddlia chondrophila 2032/99 and parachlamydia acanthamoebae uv-7. this enabled us to perform th ...201121690563
[Environmental Chlamydiae with medical significance].The molecular biological analysis of a chlamydia-like bacterium from Acanthamoeba sp., originated from the nasal mucosa of a female subject, led to the description of the new species Parachlamydia acanthamoebae. It provided the basis for establishing its own family Parachlamydiaceae, which was genetically separated from the traditional Chlamydiaceae. In the following years other chlamydia-like bacteria, replicating within different free-living amoeba species, have been observed. Due to their clo ...201121971886
permissivity of fish cell lines to three chlamydia-related bacteria: waddlia chondrophila, estrella lausannensis and parachlamydia acanthamoebae.epitheliocystis is an infectious disease affecting gills and skin of various freshwater and marine fishes, associated with high mortality and reduced growth of survivors. candidatus piscichlamydia salmonis and clavochlamydia salmonicola have recently been identified as aetiological agents of epitheliocystis in atlantic salmon. in addition, several other members of the chlamydiales order have been identified in other fish species. to clarify the pathogenicity of chlamydia-like organisms towards f ...201122092560
amoebal host-range, host-free survival and disinfection susceptibility of environmental chlamydiae as compared to chlamydia trachomatis.the term "chlamydia-like organisms" encompasses obligate intra-cellular bacterial species phylogenetically close to chlamydiaceae. most are associated with free-living amoebae and several could be responsible for respiratory tract infections and abortion in human and animals. despite increasing concern about their pathogenic role, the prevalence, biodiversity, and ecology of chlamydia-related bacteria still remain largely unknown. in this study, six members of the chlamydiales were tested, inclu ...201122141597
insight into cross-talk between intra-amoebal pathogens.amoebae are phagocytic protists where genetic exchanges might take place between amoeba-resistant bacteria. these amoebal pathogens are able to escape the phagocytic behaviour of their host. they belong to different bacterial phyla and often show a larger genome size than human-infecting pathogens. this characteristic is proposed to be the result of frequent gene exchanges with other bacteria that share a sympatric lifestyle and contrasts with the genome reduction observed among strict human pat ...201122047552
lack of effective anti-apoptotic activities restricts growth of parachlamydiaceae in insect cells.the fundamental role of programmed cell death in host defense is highlighted by the multitude of anti-apoptotic strategies evolved by various microbes, including the well-known obligate intracellular bacterial pathogens chlamydia trachomatis and chlamydia (chlamydophila) pneumoniae. as inhibition of apoptosis is assumed to be essential for a successful infection of humans by these chlamydiae, we analyzed the anti-apoptotic capacity of close relatives that occur as symbionts of amoebae and might ...201222253735
architecture and host interface of environmental chlamydiae revealed by electron cryotomography.chlamydiae comprise important pathogenic and symbiotic bacteria that alternate between morphologically and physiologically different life stages during their developmental cycle. using electron cryotomography, we characterize the ultrastructure of the developmental stages of three environmental chlamydiae: parachlamydia acanthamoebae, protochlamydia amoebophila and simkania negevensis. we show that chemical fixation and dehydration alter the cell shape of parachlamydia and that the crescent body ...201324118768
discovery of catalases in members of the chlamydiales order.catalase is an important virulence factor for survival in macrophages and other phagocytic cells. in chlamydiaceae, no catalase had been described so far. with the sequencing and annotation of the full genomes of chlamydia-related bacteria, the presence of different catalase-encoding genes has been documented. however, their distribution in the chlamydiales order and the functionality of these catalases remain unknown. phylogeny of chlamydial catalases was inferred using mrbayes, maximum likelih ...201323729651
survey of infectious etiologies of bovine abortion during mid- to late gestation in dairy herds.bovine abortion of unknown infectious etiology still remains a major economic problem. thus, we investigated whether brucella spp., listeria monocytogenes, salmonella spp., campylobacter spp. and coxiella burnetii are associated with abortion and/or stillbirth in tunisian dairy cattle. using a pan-chlamydiales pcr, we also investigated the role of chlamydiaceae, waddlia chondrophila, parachlamydia acanthamoebae and other members of the chlamydiales order in this setting. veterinary samples taken ...201424662769
crispr system acquisition and evolution of an obligate intracellular chlamydia-related bacterium.recently, a new chlamydia-related organism, protochlamydia naegleriophila knic, was discovered within a naegleria amoeba. to decipher the mechanisms at play in the modeling of genomes from the protochlamydia genus, we sequenced the full genome of pr. naegleriophila, which includes a 2,885,090 bp chromosome and a 145,285 bp megaplasmid. for the first time within the chlamydiales order, we describe the presence of a clustered regularly interspaced short palindromic repeats (crispr) system, the imm ...201627516530
lack of chlamydia-related bacteria among patients with community-acquired pneumonia. 201527257497
prevalence and diversity of chlamydiales and other amoeba-resisting bacteria in domestic drinking water systems.a growing number of human infections incriminate environmental bacteria that have evolved virulent mechanisms to resist amoebae and use them as a replicative niche. these bacteria are designated amoeba-resisting bacteria (arb). despite the isolation of these arb in various human clinical samples, the possible source of infection remains undetermined in most cases. however, it is known that the arb legionella pneumophila, for instance, causes a respiratory infection in susceptible hosts after inh ...201628070335
the high prevalence and diversity of chlamydiales dna within ixodes ricinus ticks suggest a role for ticks as reservoirs and vectors of chlamydia-related bacteria.the chlamydiales order is composed of nine families of strictly intracellular bacteria. among them, chlamydia trachomatis, c. pneumoniae, and c. psittaci are established human pathogens, whereas waddlia chondrophila and parachlamydia acanthamoebae have emerged as new pathogens in humans. however, despite their medical importance, their biodiversity and ecology remain to be studied. even if arthropods and, particularly, ticks are well known to be vectors of numerous infectious agents such as viru ...201526386066
early expression of the type iii secretion system of parachlamydia acanthamoebae during a replicative cycle within its natural host cell acanthamoeba castellanii.the type three secretion system (t3ss) operons of chlamydiales bacteria are distributed in different clusters along their chromosomes and are conserved at both the level of sequence and genetic organization. a complete characterization of the temporal expression of multiple t3ss components at the transcriptional and protein levels has been performed in parachlamydia acanthamoebae, replicating in its natural host cell acanthamoeba castellanii. the t3ss components were classified in four different ...201323861207
chlamydiaceae family, parachlamydia spp., and waddlia spp. in porcine abortion.at present, despite extensive laboratory investigations, most cases of porcine abortion remain without an etiological diagnosis. due to a lack of recent data on the abortigenic effect of order chlamydiales, 286 fetuses and their placentae of 113 abortion cases (1-5 fetuses per abortion case) were investigated by polymerase chain reaction (pcr) methods for family chlamydiaceae and selected chlamydia-like organisms such as parachlamydia acanthamoebae and waddlia chondrophila. in 0.35% of the cases ...201222855373
detection of novel chlamydiae and legionellales from human nasal samples of healthy volunteers.chlamydiae are intracellular bacterial parasites of eukaryotes, ranging from amoebae to humans. they comprise many novel members and are investigated as emerging pathogens. environmental studies highlighted similarities between the ecologies of chlamydiae and legionellae, both groups being important agents of respiratory infections. herein, we analyzed nasal samples from healthy persons, searching for the presence of amoebae, chlamydiae and legionellae. from a total of 25 samples, we recovered b ...201525697709
chlamydia trachomatis and chlamydia-like bacteria: new enemies of human pregnancies.this review provides an update on the roles of chlamydia trachomatis and the related waddlia chondrophila and parachlamydia acanthamoebae in miscarriage, stillbirths and preterm labour in humans. a broad audience, including microbiologist, infectiologists, obstetricians and gynaecologists, should be aware of the potential threat of these chlamydiales for human reproduction.201728306562
amoebal endosymbiont protochlamydia induces apoptosis to human immortal hep-2 cells.protochlamydia, an environmental chlamydia and obligate amoebal endosymbiotic bacterium, evolved to survive within protist hosts, such as acanthamobae, 700 million years ago. however, these bacteria do not live in vertebrates, including humans. this raises the possibility that interactions between protochlamydia and human cells could induce a novel cytopathic effect, leading to new insights into host-parasite relationships. therefore, we studied the effect of protochlamydia on the survival of hu ...201222276171
effect of parachlamydia acanthamoebae on pulmonary function parameters in a bovine respiratory model.the aim of this study was to evaluate pulmonary dysfunction induced by experimental infection with parachlamydia acanthamoebae in calves. intrabronchial inoculation with p. acanthamoebae was performed in 31 calves aged 2-3 months old at two different challenge doses of 10(8) and 10(10) inclusion-forming units (ifu) per animal. control animals received heat inactivated bacteria. the effects on pulmonary gas exchange were determined by arterial blood gas analysis and haemoximetry during the 7 days ...201627240907
permissivity of insect cells to waddlia chondrophila, estrella lausannensis and parachlamydia acanthamoebae.recent large scale studies questioning the presence of intracellular bacteria of the chlamydiales order in ticks and fleas revealed that arthropods, similarly to mammals, reptiles, birds or fishes, can be colonized by chlamydia-related bacteria with a predominant representation of the rhabdochlamydiaceae and parachlamydiaceae families. we thus investigated the permissivity of two insect cell lines towards waddlia chondrophila, estrella lausannensis and parachlamydia acanthamoebae, three bacteria ...201626423021
severe pneumonia due to parachlamydia acanthamoebae following intranasal inoculation: a mice model.parachlamydia acanthamoebae is an obligate intracellular bacterium naturally infecting free-living amoebae. the role of this bacterium as an agent of pneumonia is suggested by sero-epidemiological studies and molecular surveys. furthermore, p. acanthamoebae may escape macrophages microbicidal effectors. recently, we demonstrated that intratracheal inoculation of p. acanthamoebae induced pneumonia in 100% of infected mice. however, the intratracheal route of infection is not the natural way of in ...201626340890
antibiotic susceptibility of neochlamydia hartmanellae and parachlamydia acanthamoebae in amoebae.parachlamydia acanthamoebae and neochlamydia hartmanellae are chlamydia-related bacteria naturally infecting free-living amoebae. these strict intracellular bacteria might represent emerging pathogens. recent studies report an association with lower respiratory tract infections, especially with pneumonia where they have been identified as a potential causative agent in 1-2% of cases. in this study, we defined the antibiotic susceptibility of n. hartmanellae, two strains of p. acanthamoebae and t ...201626279002
absence of chlamydia-like organisms in pigs.porcine reproductive failure, especially abortion, causes significant economic loss in the pig industry. waddlia chondrophila and parachlamydia acanthamoebae are potential abortigenic agents for pigs. therefore, we investigated the presence of these two chlamydia-like organisms in abortion-related samples originating from belgian pig farms. all investigated samples remained negative.201526137311
distribution and population structure characteristics of microorganisms in urban sewage system.the sewage system functions as an important public infrastructure. the survived microbial population inside the sewage system plays an important role in the biochemical process during wastewater transportation within the system. the study aims to investigate the microbial communities spatial distribution inside manholes and sewage pipes by using the massive parallel 454 pyrosequencing combined with denaturing gradient gel electrophoresis of v1-v3 regions of 16s rrna. the microbial structure, dis ...201525981998
amoebal endosymbiont parachlamydia acanthamoebae bn9 can grow in immortal human epithelial hep-2 cells at low temperature; an in vitro model system to study chlamydial evolution.ancient chlamydiae diverged into pathogenic and environmental chlamydiae 0.7-1.4 billion years ago. however, how pathogenic chlamydiae adapted to mammalian cells that provide a stable niche at approximately 37 °c, remains unknown, although environmental chlamydiae have evolved as endosymbionts of lower eukaryotes in harsh niches of relatively low temperatures. hence, we assessed whether an environmental chlamydia, parachlamydia bn9, could grow in human hep-2 cells at a low culture temperature of ...201525643359
conserved features and major differences in the outer membrane protein composition of chlamydiae.chlamydiae are a highly successful group of obligate intracellular bacteria infecting a variety of eukaryotic hosts. outer membrane proteins involved in attachment to and uptake into host cells, and cross-linking of these proteins via disulfide bonds are key features of the biphasic chlamydial developmental cycle. in this study, we used a consensus approach to predict outer membrane proteins in the genomes of members of three chlamydial families. by analysing outer membrane protein fractions of ...201525212454
antibiotic susceptibility of estrella lausannensis, a potential emerging pathogen.estrella lausannensis is a new chlamydia-related bacterium, belonging to the criblamydiaceae family. as suggested by its species name, this bacterium harbors a peculiar star shape. e. lausannensis is able to infect a wide range of amoebal, fish and mammalian cell lines. moreover, seroprevalence of 2.9% was reported in children and in women with tubal pathology, showing that humans are commonly exposed to this recently discovered strict intracellular bacteria considered as a potential pathogen. a ...201425150688
importance of amoebae as a tool to isolate amoeba-resisting microorganisms and for their ecology and evolution: the chlamydia paradigm.free-living amoebae are distributed worldwide and are frequently in contact with humans and animals. as cysts, they can survive in very harsh conditions and resist biocides and most disinfection procedures. several microorganisms, called amoeba-resisting microorganisms (arms), have evolved to survive and multiply within these protozoa. among them are many important pathogens, such as legionella and mycobacteria, and also several newly discovered chlamydia-related bacteria, such as parachlamydia ...201424992529
a bovine model of a respiratory parachlamydia acanthamoebae infection.the aim of this study was to evaluate the pathogenicity of parachlamydia (p.) acanthamoebae as a potential agent of lower respiratory tract disease in a bovine model of induced lung infection. intrabronchial inoculation with p. acanthamoebae was performed in healthy calves aged 2-3 months using two challenge doses: 10(8) and 10(10) bacteria per animal. controls received 10(8) heat-inactivated bacteria. challenge with 10(8) viable parachlamydia resulted in a mild degree of general indisposition, ...201524989139
chlamydiaceae and chlamydia-like organisms in free-living small mammals in europe and afghanistan.few data are available on the occurrence of chlamydial infections in wild small mammals. we investigated the significance of free-living small mammals as reservoirs or transmission hosts for microorganisms of the phylum/class chlamydiae. we obtained 3,664 tissue samples from 911 animals in switzerland, germany, austria, the czech republic, and afghanistan. samples included internal organs (n = 3,652) and feces (n = 12) from 679 rodents (order rodentia) and 232 insectivores (order soricomorpha) a ...201424484495
crescent and star shapes of members of the chlamydiales order: impact of fixative methods.members of the chlamydiales order all share a biphasic lifecycle alternating between small infectious particles, the elementary bodies (ebs) and larger intracellular forms able to replicate, the reticulate bodies. whereas the classical chlamydia usually harbours round-shaped ebs, some members of the chlamydia-related families display crescent and star-shaped morphologies by electron microscopy. to determine the impact of fixative methods on the shape of the bacterial cells, different buffer and ...201323942615
a domino-like chlamydial attachment process: concurrent parachlamydia acanthamoebae attachment to amoebae is required for several amoebal released molecules and serine protease activity.parachlamydia acanthamoebae is an obligate intracellular bacterium that infects free-living amoebae (acanthamoeba), and is a potential human pathogen associated with hospital-acquired pneumonia. the attachment mechanism of this bacteria to host cells is crucial in bacterial pathogenesis, yet remains undetermined. hence, we obtained monoclonal antibodies (mabs) specific to either p. acanthamoebae or amoebae in an attempt to elucidate the attachment mechanism involved. hybridomas of 954 clones wer ...201222403190
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