Search PubMed⌕ Search

Biomedical subjects

D Raoult

Publications and source records attributed to D Raoult.

At least 487 records · Page 27Linked to original sources
PubMed1990

In vitro susceptibility of Ehrlichia sennetsu to antibiotics.

Antibiotic efficacies were evaluated by Diff-Quik (Dade, Düdingen, Federal Republic of Germany) staining of Ehrlichia sennetsu in P388D1 murine macrophages grown in 96-well microtiter plates. Sennetsu disease is generally cured with tetracyclines. In vivo, E. sennetsu is susceptible to doxycycline and is resistant to erythromycin, penicillin, and chloramphenicol. Our study confirmed, in vitro, the efficacy of doxycycline, which had an MIC of 0.125 micrograms/ml. E. sennetsu was found to be resistant to erythromycin, chloramphenicol, penicillin, gentamicin, and co-trimoxazole, while it was very susceptible to ciprofloxacin (MIC, 0.125 micrograms/ml) and rifampin (MIC, 0.5 micrograms/ml).

Animals↗
PubMed1990

Secretion of tissue-type plasminogen activator and plasminogen activator inhibitor by Rickettsia conorii- and Rickettsia rickettsii-infected cultured endothelial cells.

Hemostasis abnormalities have been described in patients with Mediterranean spotted fever and Rocky Mountain spotted fever. Evidence of the activation of the fibrinolytic system has been obtained in both diseases. After experimental Rocky Mountain spotted fever, an elevated level of fibrinogen was found in parallel with the activation of the fibrinolytic system and transient elevation of the tissue-type plasminogen activator. Later protein is mainly synthesized by endothelial cells. The ability to culture human endothelial cells in vitro provides a unique system to study the secretion of tissue-type plasminogen activator and of plasminogen activator inhibitor after rickettsial infection. Human vascular endothelial cells derived from the umbilical vein, when infected with Rickettsia conorii or Rickettsia rickettsii, secreted as much tissue-type plasminogen activator as control cells. The activity of plasminogen activator inhibitor however, was higher in the supernatants of infected cells than in those of control cells. This rickettsia-induced imbalance of the tissue-type plasminogen activator-inhibitor pair was a very early event after in vitro infection. The involvement of this system during Mediterranean spotted fever and Rocky Mountain spotted fever remains to be demonstrated.

Antibodies, Monoclonal↗
PubMed1990

Isolation of 16 strains of Coxiella burnetii from patients by using a sensitive centrifugation cell culture system and establishment of the strains in HEL cells.

Q fever, caused by Coxiella burnetii, may be acute or chronic. Only a few strains of C. burnetii have been isolated due to the difficulty and hazard of isolation. We report here the isolation using a centrifugation shell vial technique of 16 new strains from patients suffering chronic Q fever. Twenty-four samples were inoculated onto human embryonic lung (HEL) fibroblast cell monolayers growing in shell vials. C. burnetii was detected 6 days later by using immunofluorescence. Samples from valves (n = 10), arterial prostheses (n = 2), bone (n = 3), skin biopsy (n = 1), bone marrow (n = 1), and blood (n = 5) from 16 patients were successfully cultured. Two cerebrospinal fluid samples from two patients were negative. The strains were subcultured in HEL cells and are now established. The technique is sensitive and less hazardous than animal inoculation. We recommend the shell vial technique for isolation of C. burnetii.

Bacteriological Techniques↗
PubMed1990

Isolation by a sensitive centrifugation cell culture system of 52 strains of spotted fever group rickettsiae from ticks collected in France.

Boutonneuse fever caused by Rickettsia conorii is transmitted mainly by the brown dog tick, Rhipicephalus sanguineus. We collected 540 ticks in Marseille, France, and tried to isolate as many strains of rickettsia as possible. Ticks were evaluated for the presence of rickettsia by the hemolymph test and by a new culture system, the centrifugation-shell vial technique. We avoided contamination in the culture system. Prior to ticks being submitted to the hemolymph test, they were disinfected. Only 5.6% (27 of 478) of the cultures were contaminated. A drop of hemolymph from each of 478 R. sanguineus ticks was cultured in two shell vials, and another drop was stained by the Gimenez method or indirect immunofluorescence. Since Gimenez staining in our hands was not satisfactory, comparison of the hemolymph test and culture is based on the results of indirect immunofluorescence. Thus, 50 of 369 (13.5%) examined ticks were hemolymph test positive, and 44 (11.9%) cultures were positive. After disinfection, another pool of 62 ticks were examined by the hemolymph test. The ticks were kept individually in a sterile environment. A few days later, the hemolymph of these ticks was collected again and cultured. The contamination rate was not significantly higher (6.4%) than in the above-described conditions. It allowed us to isolate eight more strains. Thus, we recommend screening ticks with the hemolymph test and culturing only the hemolymph test-positive ticks.

Animals↗
PubMed1990

[Meningoencephalitis caused by Coxiella burnetii].

Meningoencephalitis caused by Coxiella burnetii is exceptional and its clinical presentation is varied. We report a case which presented as transient central neurological deficits and intracranial hypertension without fever. The condition was diagnosed by indirect immunofluorescence.

Adult↗
PubMed1989

The line blot: an immunoassay for monoclonal and other antibodies. Its application to the serotyping of gram-negative bacteria.

A procedure is described for assaying antibodies based on the application of antigen to nitrocellulose as a line with an ink pen point. The method requires no expensive apparatus, is easy to perform, and requires less than 0.25 micrograms of antigen per assay. More than 45 antigens can be assayed simultaneously with a single antibody. Antigens can be applied as purified proteins, extracts, or sodium dodecyl sulfate solubilized extracts. The application of the line blot assay for the detection of monoclonal antibodies which recognize heat-sensitive and insensitive epitopes on the typhus rickettsia surface protein antigen is described. A new serotyping assay for Gram-negative bacteria is also described in which sodium dodecyl sulfate solubilized antigens are applied as lines with and without prior proteinase K digestion. The value of the line blot serotyping assay is demonstrated with Proteus. Rickettsia, Rochalimaea, and Legionella antigens. The line blot immunoassay is a simple, but powerful and flexible, alternative to dot and cross-dot immunoassays.

Antibodies, Monoclonal↗
PubMed1989

Antibiotic susceptibility of rickettsia and treatment of rickettsioses.

The author describes the in vitro data for antibiotic susceptibility of Rickettsia and Coxiella burnetti. Tetracyclines are still the first antibiotic choice in spotted fevers, typhus and Q fever. In spotted fever a shortened treatment is suggested and the place of macrolide antibiotics, such as Josamycin, in treating children may be evaluated. In Q fever, according to the new biological data, an association of tetracyclines and Rifampin or Quinolones is suggested.

Anti-Bacterial Agents↗
PubMed1989

Q-fever and autoimmunity.

STUDY OBJECTIVE: To determine the incidence and the clinical significance of two autoimmune markers in Q-fever (smooth muscle antibodies, cold agglutinins). DESIGN: Six index cases with auto-immune disorders. Assays of 104 sera from patients with Q-fever (including index cases) using immunofluorescence for smooth muscle antibodies, microagglutination for cold agglutinins. SETTING: French National Reference Center for Rickettsial Diseases. CASES: 6 patients were studied with acute Q-fever and auto-immune disorders. 3 of whom had presented a resistance to a therapy with antibiotics. Stored samples from other patients with acute or chronic stage were also screened to appreciate the incidence of the two markers. MEASUREMENTS AND MAIN RESULTS CASE REPORTS: No correlation between Q-fever and smooth muscle antibodies titers and kinetics were found. A spurt of corticosteroids was necessary to obtain apyrexia for the patients who had presented multiple auto-immune disorders and a resistance to the classical therapy. INCIDENCE; Smooth muscle antibodies were detected in 27%, cold agglutinins in one case. They were present in 23% of the patients with acute cases and in 38% with chronic stage. CONCLUSION: The incidence of auto-immune disorders is unexpectedly high and could explain some manifestations of acute Q-fever e.g the resistance to therapy with antibiotics which are not yet clear. Then the association during the acute stage of auto-immune disorders with the persistence of clinical or biological findings after three weeks therapy could recommend the use of corticosteroids.

Adult↗
PubMed1989

Lack of co-transmission of Rickettsia conorii and Ehrlichia canis in human beings in the south of France.

Ehrlichia canis is the agent of canine Ehrlichiosis, commonly known as canine tropical pancytopenia. This canine disease is frequent in our area, as is Mediterranean Spotted Fever in humans. Recently a few cases of human Ehrlichiosis have been described in the USA. The supposed vector of both diseases is Rhipicephalus sanguineus. In order to evaluate the co-transmission of these two diseases, we selected 498 human sera positive for R. conorii and tested them for Ehrlichia canis. None of them were positive, suggesting the lack of co-transmission of the diseases.

Animals↗
PubMed1989

Evaluation of a latex agglutination test for Rickettsia conorii antibodies in seropositive patients.

A latex agglutination test for antibodies to Rickettsia conorii was compared with micro-immunofluorescence (the reference test for total antibodies); 179 sera were from 115 confirmed cases of Mediterranean Spotted Fever, and 101 were from pregnant women (control group) who had no detectable antibodies by the reference method. The micro-immunofluorescence test for specific IgM antibodies was used to clarify some discordant results. The agreement obtained between latex-R. conorii and micro-immunofluorescence was 95%. Sensitivity and specificity were 96% and 93% respectively. When micro-immunofluorescence results for specific IgM antibodies were included, these figures rose to 96 and 99%, and agreement was almost 97%. Latex agglutination is a simpler and more rapid technique than micro-immunofluorescence and is suitable for the screening as well as for the titration of R. conorii antibodies.

Antibodies, Bacterial↗
PubMed1989

Cross-reaction of immune sera from patients with rickettsial diseases.

Rickettsia rickettsii and Rickettsia conorii are the causative agents of two common and serious diseases, Rocky Mountain spotted fever and Mediterranean spotted fever, respectively. In patients naturally infected with either of these organisms, antibodies are produced which cross-react with antigens of the other so extensively that diagnostic tests usually cannot identify the causative agents. The results of this study indicate that serodiagnostic tests with antigen from one of these two organisms could be used to detect antibodies in patients with either of the two rickettsial diseases.

Antibodies, Bacterial↗
PubMed1989

In vitro susceptibilities of Rickettsia rickettsii and Rickettsia conorii to roxithromycin and pristinamycin.

In vitro susceptibilities of Rickettsia rickettsii and Rickettsia conorii to roxithromycin, pristinamycin, and the pristinamycin compounds, P1 and P2, were determined by a dye uptake assay and a plaque assay. The MICs were 1 microgram/ml for roxithromycin, 2 micrograms/ml for pristinamycin, greater than 256 micrograms/ml for P1, and 2 micrograms/ml for P2. Compounds P1 and P2 did not share synergetic activity. The toxicity of each compound was determined by a dye uptake assay. Toxic concentrations were 128 micrograms/ml for roxithromycin, 32 micrograms/ml for pristinamycin, greater than 256 micrograms/ml for P1, and 32 micrograms/ml for P2. Roxithromycin and pristinamycin could be useful in the treatment of Rocky Mountain spotted fever and Mediterranean spotted fever.

Animals↗
PubMed1989

Susceptibility of Coxiella burnetii to pefloxacin and ofloxacin in ovo and in persistently infected L929 cells.

The relative lack of efficacy of the antibiotic treatment of chronic Q fever endocarditis justifies the further evaluation of the susceptibility of Coxiella burnetii to the modern quinolone antibiotics. We evaluated the efficacies of pefloxacin and ofloxacin in controlling the Nine Mile isolate of C. burnetii by using an embryonated egg assay and persistently infected L929 cells in culture. Pefloxacin was effective in controlling the intracellular parasite at a concentration of 50 micrograms per egg and 1 microgram/ml in cultures of infected cells. Ofloxacin was effective at a concentration of 25 micrograms per egg and 0.5 microgram/ml in infected-cell cultures. In light of the fact that the concentrations of antibiotics used fall within physiological ranges used in humans, ofloxacin and pefloxacin may be useful in the clinical management of chronic Q fever, for which, to date, results have been poor.

Animals↗
PubMed1989

Cross-reaction with Borrelia burgdorferi antigen of sera from patients with human immunodeficiency virus infection, syphilis, and leptospirosis.

We have studied the cross-reaction with Borrelia burgdorferi of sera positive for leptospirosis, syphilis, or human immunodeficiency virus by using the microimmunofluorescence test (micro-IF). The percentage of sera reactive in the micro-IF before absorption varied from 7 to 37% and was reduced to 3 to 8% after absorption with a commercial Reiter treponemal antigen. The cross-reaction of sera positive for syphilis or human immunodeficiency virus was distinguished from the homologous reaction with sera from patients with Lyme disease in the immunoblot test results. However, the cross-reaction could not always be distinguished from the homologous reaction with sera from patients with leptospirosis whose sera scored positive in the micro-IF for B. burgdorferi.

Acquired Immunodeficiency Syndrome↗