Search PubMed⌕ Search

Biomedical subjects

Danielle Venditti

Publications and source records attributed to Danielle Venditti.

7 recordsLinked to original sources
PubMed2006

'Candidatus Rhabdochlamydia crassificans', an intracellular bacterial pathogen of the cockroach Blatta orientalis (Insecta: Blattodea).

The genus Rickettsiella comprises various intracellular bacterial pathogens of arthropods, exhibiting a chlamydia-like developmental cycle. Species may be divided into two main groups, the R. popilliae-R. grylli group and the R. chironomi group. Previous phylogenetic studies based on the 16S ribosomal RNA encoding gene showed that two Rickettsiella species, one from each group, belong in reality to two distantly related lineages, the gamma-Proteobacteria (R. grylli) and the Chlamydiales ('Candidatus Rhabdochlamydia porcellionis', a pathogen of terrestrial isopods). In the present work, the 16S rDNA sequence of another Rickettsiella-like species, causing abdominal swelling to its cockroach host Blatta orientalis, was determined and phylogenetic analysis performed. Identical 16S rDNA sequences of 1495 nucleotides were obtained from fat body and ovary tissues of both healthy and diseased cockroach individuals. The sequence shared only 73% of similarity with R. grylli, but 82-87% with most Chlamydiales, and even 96.3% with 'Candidatus Rhabdochlamydia porcellionis'. Phylogenetic analyses confirmed the affiliation of the cockroach pathogen within the order Chlamydiales, and based on ultrastructural characteristics and genetic analyses, we propose its inclusion in the 'Candidatus Rhabdochlamydia' as a distinct taxon, 'Candidatus Rhabdochlamydia crassificans'. These results extend our knowledge of the phylogenetic diversity of the Chlamydiales.

Animals↗
PubMed2004

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 diversity of chlamydiae from both environmental and clinical samples, most of such a diversity could be formed by novel lineages of chlamydiae. Experimental studies showed that free-living amoebae may support multiplication of various chlamydiae, then could play an important role as reservoir/vector of chlamydial infections. Here we reviewed literature data concerning chlamydial infections, with a particular emphasis on the novely described chlamydial organisms.

Abortion, Spontaneous↗
PubMed2003

Increasing diversity within Chlamydiae.

In recent years, 16S ribosomal DNA analyses has allowed the recognition of new chlamydia organisms, requiring the creation of new species, genera, and families within this unique, deep lineage of prokaryotes. The trachoma and psittaci groups chlamydiae are now recognized as separate genera, Chlamydia and Chlamydophila, respectively, and biovars of each group have been elevated to the species rank. Simkania and Parachlamydia have been associated with human respiratory infections, while Waddlia seems to be implicated in abortion in bovins. DNA amplification studies targeting the 16S rDNA have revealed a richer diversity within chlamydiae, identifying new lineages from both environmental and clinical samples. Further studies will be of interest to both examine the ecology and evaluate the clinical importance of these novel chlamydiae. Herein, we provide a summary of literature and our data about the novel chlamydial lineages.

Chlamydia↗
PubMed2002

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 16S rDNA-based molecular studies, and their implication in human infections is poorly known. By using a pan-chlamydia 16S rDNA PCR, we have searched for the presence of chlamydiae in 228 clinical samples that all previously had been shown to be PCR-negative for Chlamydophila pneumoniae: 170 respiratory samples, 45 atheromatic plaques and 13 peripheral blood mononuclear cell samples. Nine respiratory samples tested positive. Sequence analysis has allowed us to assign four sequences to Chlamydophila psittaci, three sequences to Chlamydophila felis, and two sequences to two novel phylotypes belonging to the Parachlamydiaceae. These latter sequences showed similarity values of more than 93% with each other and with the P. acanthamoebae sequence, thus belonging to novel, unrecognized species. In conclusion, this report showed that a variety of non-C. pneumoniae chlamydial respiratory infection is present in humans, and that new parachlamydiae distinct from P. acanthamoebae may be detected in human clinical samples. Future studies will be of interest in order to estimate the diversity of these novel chlamydiae in both clinical and environmental samples, as well as their possible clinical implication in human and animal infections.

Adolescent↗
PubMedDate not supplied

Diversity of the parachlamydiae in the environment.

Chlamydiae are obligate intracellular bacteria, parasites of a variety of eukaryotes ranging from amoebae to humans. Among them, the family Parachlamydiaceae comprises endosymbionts of amoebae, mainly Acanthamoeba, currently investigated as emerging pathogens of humans and other vertebrates. 16S rDNA-based PCR culture-independent studies in environmental samples have demonstrated the presence of Chlamydiales in various types of nonmedical habitats. Here we reviewed the biology of the Parachlamydiaceae, and more particularly those studies reporting molecular evidences for their presence in the environment, with a re-analysis of the 16S rDNA phylotypes.

Acanthamoeba↗