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Biomedical subjects

D Raoult

Publications and source records attributed to D Raoult.

At least 325 records · Page 18Linked to original sources
PubMed1996

Differentiation of spotted fever group rickettsiae by sequencing and analysis of restriction fragment length polymorphism of PCR-amplified DNA of the gene encoding the protein rOmpA.

Currently, the genotypic identification of the spotted fever group (SFG) rickettsiae is based on restriction fragment length polymorphism analysis of PCR-amplified genes coding for the enzyme citrate synthase and the surface proteins rOmpA and rOmpB. A set of useful restriction endonucleases was found following comparison of Rickettsia rickettsii and R. prowazekii sequences. However, by using three PCR amplifications and four enzyme digestions with this set, it was impossible to differentiate between all of the known serotypes of the SFG rickettsiae. We amplified by PCR and sequenced using an automated laser fluorescent DNA sequencer a fragment of the gene encoding the protein rOmpA from 21 serotypes of the SFG rickettsiae. A 632-bp amplification product was obtained for most of the strains, although no product could be obtained by using R. akari, R. australis, R. helvetica, and R. bellii DNAs. We found a characteristic sequence for all strains studied except the two isolates of R. massiliae, isolates GS and Mtul. Using the software package BISANCE, we determined the restriction map of this fragment and identified five potentially useful endonucleases, RsaI, AluI, PstI, XbaI, and AvaII. We confirmed the computer analysis-derived profiles by PCR-restriction fragment length polymorphism analysis. The combination of the profiles obtained after digestion of the PCR product by RsaI and PstI allowed for the differentiation of 16 strains. The use of AluI and XbaI allowed for the characterization of R. parkeri and strain HA-91, respectively. R. africae and strain S were differentiated by AvaII digestion. Thus, using a single PCR amplification, we were able to differentiate all of the SFG rickettsiae whose ompA gene was amplified by PCR.

Bacterial Outer Membrane Proteins↗
PubMed1996

Serological cross-reactions between Bartonella quintana, Bartonella henselae, and Coxiella burnetii.

The clinical manifestations of Q fever and bartonelloses can be confused, especially in cases of infectious endocarditis. Differential diagnosis of the diseases is important because the treatments required for Q fever and bartonelloses are different. Laboratory confirmation of a suspected case of either Q fever or bartonelloses is most commonly made by antibody estimation with an indirect immunofluorescence assay. With an indirect immunofluorescence assay, 258 serum samples from patients with Q fever were tested against Bartonella henselae and Bartonella quintana antigens, and 77 serum samples from patients with infection by Bartonella sp. were tested against Coxiella burnetii antigen. Cross-reactivity was observed: more than 50% of the chronic Q fever patients tested had antibodies which reacted against B. henselae antigen to a significant level. This cross-reaction was confirmed by a cross-adsorption study and protein immunoblotting. However, because the levels of specific antibody titers in cases of Bartonella endocarditis are typically extremely high, low-level cross-reaction between C. burnetii antibodies and B. henselae antigen in cases of Q fever endocarditis should not lead to misdiagnosis, provided serology testing for both agents is performed.

Angiomatosis, Bacillary↗
PubMed1996

Proliferative glomerulonephritis revealing chronic Q fever.

We describe the case of a 69-year-old male with a year-long history of renal failure. Investigation revealed proliferative glomerulonephritis, cryoglobulinemia, and Q fever endocarditis. Renal tissue examination for the presence of Coxiella burnetii was positive. The patient was treated by doxycycline and chloroquine; his clinical status, renal failure, and chronic Q fever have dramatically improved.

Aged↗
PubMed1996

Optimum treatment of intracellular infection.

The intracellular location of some micro-organisms has been early recognised as a critical point to explain failure of antibiotic therapy to eradicate such pathogens from infected hosts. Most often parasites invade 'professional' phagocytic cells, including neutrophils, monocytes and macrophages, by resisting the intracellular bactericidal phagolysosomal pathway. Alternatively, they may invade 'non-professional' phagocytic cells (cells with fewer phagocytic and bactericidal abilities) such as endothelial cells, or even cells without lysosomes such as erythrocytes. The intracellular activity of an antibiotic depends on several factors including its ability to reach the eukaryotic cell membrane, its subcellular localisation as compared to that of the parasite, the possibility that the intracellular milieu may partially inactivate its activity, and the susceptibility of the intracellular form of the parasite. In vitro and animal models have been developed to investigate antibiotic activity against intracellular pathogens. However, it should be emphasised that only data obtained from patients give reliable information to define the optimum antibiotic regimen.

Alphaproteobacteria↗
PubMed1996

Evaluation of serological response to Bartonella henselae, Bartonella quintana and Afipia felis antigens in 64 patients with suspected cat-scratch disease.

The serological response to Bartonella henselae, B. quintana, and Afipia felis was assessed by an indirect fluorescence antibody test (IFAT) in 64 patients with suspected cat-scratch disease (CSD) recruited from the Bordeaux area in France. Blood samples were collected from 57 patients with chronic lymphadenopathy who underwent lymph-node biopsy with suggestive histopathologic features of CSD, and from an additional 7 patients with suspected CSD who underwent surgical incision and drainage because of lymph-node tenderness. Of the patients, 31 were male and 33 female, with a median age of 27 years (range 2-89). 69.8% reported cat and/or dog contact. Of the 26/64 (40.6%) patients, serum samples were positive at a titer of 1:100 or more for immunoglobulin G (IgG) antibodies (17 only to B. henselae, 1 only to B. quintana, 3 only to Afipia felis, and 5 to both B. henselae and B. quintana). IgM or IgA antibodies were also detected in 10 patients with IgG antibodies to B. henselae. 11 (17.2%) of the 64 patient serum samples were positive at a low titer of 1:50. These data suggested that serological response assessed by standard IFAT is not enough to confirm a CSD diagnosis.

Adolescent↗
PubMed1996

Biological and genetic characterization of Rickettsia sibirica strains isolated in the endemic area of the north Asian tick typhus.

Restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction-amplified gene fragments was used to characterize 24 isolates of spotted fever group rickettsiae previously identified as Rickettsia sibirica from their serologic properties. These strains were obtained in Russia between 1946 and 1991 from humans and different species of Ixodid ticks. The RFLP analysis was performed using amplified DNA products obtained with a genus-specific primer pair derived from the R. prowazekii citrate synthase gene and two group-specific primer pairs from the R. rickettsii 190-kD and 120-kD surface protein antigen genes followed by Alu I, Pst I, and Rsa I restriction endonuclease digestions. Although some differences were detected in biological characteristics among the examined strains, only a single R. sibirica genotype was found with these molecular tools of identification.

Animals↗
PubMed1996

Image cytometry and topographical analysis of proliferation of endothelial cells in vitro during Bartonella (Rochalimaea) infection.

Bartonella quintana and Bartonella henselae are clinically associated with proliferative neovascular lesions. The effect of Bartonella infection on human endothelial cells was evaluated in vitro by quantitative image analysis. Particular emphasis is placed on reporting the methodologies employed. Human umbilical vein endothelial cells were infected in vitro with the two Bartonella species. Cell proliferation (cell density), cell morphology (cell surface, form and elongation factors) and spatial reorganization (global topographical analysis and hierarchical cluster detection) were monitored over a 3-day period of infection. Firstly, infection stimulated endothelial cell proliferation. Secondly, infection induced obvious morphological changes; infected cells became larger, more elongated and spindle-shaped. Cytoskeletal reorganization was confirmed by staining of F actin. Thirdly, infection altered the spatial organization of cells within the monolayer; this could not have been due solely to the morphological modifications they experienced. This model demonstrates that Bartonella infection provoked endothelial cell proliferation, topographical rearrangements and morphological changes because of modifications of the cytoskeleton. These experimental findings provide a physiopathological explanation to the abnormal angiogenesis observed in bacillary angiomatosis.

Bartonella↗
PubMed1996

Bartonella (Rochalimaea) henselae in southern Africa--evidence for infections in domestic cats and implications for veterinarians.

Substantial evidence has recently accumulated showing domestic cats to be the principal reservoirs of Bartonella henselae, the aetiological agent of human diseases including cat-scratch disease, bacillary angiomatosis, bacillary peliosis and a febrile bacteraemia syndrome. To determine the prevalence of antibodies reactive with Bartonella henselae in cats from southern Africa, indirect fluorescent antibody assays were carried out on feline sera from South Africa and Zimbabwe. Overall, 23% (39/171) of cats had antibody titres > or = 1/64, with cats from Zimbabwe (24%; 28/119) having higher seroprevalences than those from South Africa (21%; 11/52) although this difference was not statistically significant. The implications of these findings for veterinarians in southern Africa are discussed.

Adolescent↗
PubMed1995

The 16S-23S rRNA intergenic spacer region of Bartonella (Rochalimaea) species is longer than usually described in other bacteria.

We amplified by polymerase chain reaction (PCR) and sequenced using an automated laser fluorescent DNA sequencer (Pharmacia) the intergenic spacer region (ITS) between the 16S and 23S rRNAs of the four species of Rochalimaea which were recently renamed Bartonella sp. We obtained DNA fragments of 1211, 1262, 1258 and 1529 bp for the reference species of B. quintana, B. henselae, B. vinsonii and B. elizabethae, respectively. The ITS of the four species are longer than previously reported in prokaryotes and contained the genes encoding isoleucine-tRNA (tRNA(Ile)) and alanine-tRNA (tRNA(Ala)). The sequences of the tRNA(Ala) genes are identical for the four Bartonella species, but the tRNA(Ile) gene sequence of B. quintana presents one mutation in comparison with the other species.

Bartonella↗
PubMed1995

Bartonella (Rochalimaea) quintana endocarditis in three homeless men.

BACKGROUND: Bartonella (Rochalimaea) quintana is the agent of trench fever and is transmitted by the body louse. We searched for this organism in three alcoholic homeless men with endocarditis. METHODS: Blood samples were cultured on a human endothelial cell line and on blood agar. Bacteria were identified by sequencing the amplified 16S ribosomal RNA gene. The presence of bartonella in tissue was assessed by Gram's staining, immunostaining, and polymerase-chain-reaction amplification. Serologic studies for antibodies to bartonella species were performed by indirect immunofluorescence and Western immunoblotting. RESULTS: B. quintana was isolated from one patient in the blood-agar culture and from the other two patients in the endothelial-cell culture. The organism was also identified by both immunostaining and molecular techniques in the valvular vegetations from the three patients and in a cervical lymph node from one patient. The 16S ribosomal RNA gene sequences of the three isolates were almost identical to that of the prototype strain of B. quintana. High titers of antibodies to B. quintana were detected in all three patients, but so were cross-reacting antibodies to chlamydia species. In all three patients studies were repeatedly negative for antibodies to the human immunodeficiency virus. CONCLUSIONS: B. quintana is a cause of endocarditis in homeless patients and may be serologically misdiagnosed as a chlamydial infection.

Adult↗
PubMed1995

[Cat-scratch disease and disease caused by Bartonella (Rochalimaea)].

The aetiology of cat scratch disease remains controversial since both Afipia felis and Bartonella (Rochalimaea) henselae have been isolated from diseased lymph nodes. Bartonella henselae, Bartonella (Rochalimaea) quintana and Bartonella (Rochalimaea) elizabethae cause endocarditis and Bartonella bacilliformis cause septicemia (Oroya's fever) in non-immunocompromized patients, and Bartonella henselae and Bartonella quintana cause fever, bacillary angiomatosis, and visceral peliosis in human immunodeficiency virus-infected patients. Bartonella quintana is the historical agent of trench fever and we recently isolated it from chronic adenopathy. The diagnosis of Afipia felis and Bartonella infections relies upon the isolation of the bacterium from blood, node tissue after inoculation of cell cultures systems and molecular identification, and upon the serology. In vitro both species are sensitive to aminoglycosides, and we recommend aminoglycosides be included in antibiotic regimens for treating cat scratch disease and Bartonella infections.

Anti-Bacterial Agents↗
PubMed1995

Seroepidemiology of rickettsial infections in Morocco.

The prevalence of antibodies reactive with Rickettsia conorii, Rickettsia typhi, Coxiella burnetii and Ehrlichia chaffeensis was investigated using indirect immunofluorescence (IFA) test on human sera obtained from 300 blood donors in Casablanca and 126 sera obtained from clinical laboratories in Fez. In sera from Casablanca, antibodies reactive at titers > or = 1:32 were found against R. conorii (7%), and R. typhi (1.7%), but not against E. chaffeensis. In the sera from Fez, antibodies were also detected against R. conorii (5.6%), R. typhi (4%), but not against E. chaffeensis. By Western immunoblotting, seroprevalence for R. conorii was in Casablanca and 4.8% in Fez. Antibodies reactive at titers > or = 1:50 against C. burnetii (phase II) were present in sera from Casablanca (1%) and Fez (18.3%).

Adolescent↗
PubMed1995

Serologic response to rickettsial antigens in patients with Astrakhan fever.

Astrakhan fever is a new spotted fever group (SFG) rickettsiosis. Sera of patients with Astrakhan fever have been examined by microimmunofluorescence and western immunoblotting to determine the serologic responses to the Astrakhan strain and to R. conorii M-1 strain and the Israelian isolate of SFG rickettsiae. The serologic response to specific rickettsial agent and to Israelian isolate has been found to be similar, but was different of that to R. conorii. Immunoglobulin G (IgG) and IgM antibodies were detected in most sera and were directed against the lipopolysaccharide. Only one of tested sera contained IgG antibodies which also recognized high molecular weight proteins.

Antibodies, Bacterial↗