Search PubMed⌕ Search

Biomedical subjects

D Raoult

Publications and source records attributed to D Raoult.

At least 379 records · Page 21Linked to original sources
PubMed1994

[The role of new molecules in surgical antibiotic prophylaxis].

The preoperative administration of a new antibiotic for antimicrobial prophylaxis is questionable because of the methodological difficulties to demonstrate its efficiency and benefits in decreasing the postoperative infectious complications. As their rate is very low, especially in clean surgery, the number of patients to be included in a comparative trial is very high. Most studies assessed only small groups and therefore any extrapolation for clinical practice is of limited value. Because of their therapeutic efficiency the fluoroquinolones are often recommended for antimicrobial prophylaxis. However, the rapid occurrence of resistances, directly related to their prescription should invite the prescribers to be cautions. They should be contra-indicated as long as an alternative of similar efficiency is existing, in case of bacteraemia, when an administration of more than 48 hours in required or when the intra-hospital resistance rate exceeds 10 p. 100.

Anti-Bacterial Agents↗
PubMed1994

Monoclonal antibodies to Coxiella burnetii for antigenic detection in cell cultures and in paraffin-embedded tissues.

The authors developed monoclonal antibodies to Coxiella burnetti, the agent of Q fever. The selected monoclonal antibody, Cox1D8, did not cross-react with other bacteria and was used for early detection of C burnetti in shell vial cell cultures and for staining C burnetii in paraffin embedded tissues. Formalin or Bouin fixation did not alter the reactivity of the antigen with the antibody. This monoclonal antibody could be useful in the pathologic diagnosis of Q fever hepatitis and endocarditis.

Animals↗
PubMed1994

Monoclonal antibodies to Afipia felis--a putative agent of cat scratch disease.

Twelve hybridoma clones producing monoclonal antibodies to Afipia felis, a putative causative agent of cat scratch disease, were derived from BALB/c mice immunized with A felis. All 12 monoclonal antibodies were species-specific for A felis and reacted with lipopolysaccharide antigens of A felis. These monoclonal antibodies belong to immunoglobulin (Ig) G1, IgG2a, IgG2b, IgG3, and IgM isotypes. All monoclonal antibodies reacted with both agar-grown A felis and tissue culture-propagated A felis. Formalin fixation did not alter the reactivity of the antigen with the monoclonal antibodies. These monoclonal antibodies could be a useful tool for investigation of the disputed role of A felis in cat scratch disease.

Animals↗
PubMed1994

Brain abscess due to Gordona terrae in an immunocompromised child: case report and review of infections caused by G. terrae.

A brain abscess complicated antineoplastic chemotherapy for a primary cerebral rhabdoid tumor in an immunocompromised boy. Culture of purulent exudate obtained by surgical puncture of an intracranial hematoma yielded a gram-positive microorganism initially identified as a Rhodococcus species by conventional biochemical analysis; however, the isolate was subsequently identified as Gordona terrae by ribosomal DNA analysis. To our knowledge, this is the third case of human infection caused by G. terrae and the first case of a brain abscess due to this organism. As this case demonstrates, this species may cause opportunistic invasive infection in severely immunocompromised patients. The identity of clinical isolates believed to be G. terrae should be confirmed by molecular methods until better species-specific phenotypic markers become available.

Actinomycetales↗
PubMed1994

Phagolysosomal alkalinization and intracellular killing of Staphylococcus aureus by amikacin.

The aminoglycosides are ineffective against intracellular Staphylococcus aureus, which resides within lysosomes, despite a strong extracellular bactericidal activity. Since they are slowly concentrated within lysosomes it was hypothesized that acidity within these cell compartments might impair antibiotic activity. The bactericidal activity of amikacin alone and combined with lysosomotropic alkalinizing agents (LAA), which can alkalinize acidic cell compartments, was evaluated. Before antibiotic challenge, some cells were preincubated with amikacin for 3 days to allow intracellular accumulation of drug. No intracellular killing activity was shown when non-preincubated cells were used. Conversely, with preincubated cells, S. aureus was killed within 4 h when LAA were incorporated into the incubation media but not with amikacin alone. Enhanced antimicrobial activity correlated with increase in lysosomal pH. Intracellular accumulation of amikacin was not changed by LAA. These results provide evidence that acidic pH within lysosomes impairs amikacin in killing S. aureus.

Amikacin↗
PubMed1994

Taxonomic position of the rickettsiae: current knowledge.

The term rickettsiae initially encompassed all intracellular bacteria. Early rickettsial taxonomy was based on a comparison of a few phenotypic characteristics and recently, molecular studies brought new bases for rickettsial taxonomy. All rickettsial species studied so far belong to the alpha and gamma groups of the Proteobacteria. Ehrlichiae complex groups Cowdria ruminantium, Anaplasma marginale and Wolbachia pipientis and the related parthenogenesis and cytoplasmic incompatibility bacteria, whereas Rochalimaea species group with Bartonella bacilliformis. Rickettsia tsutsugamushi may form an independent lineage, whereas molecular data allow to regroup serologically defined typhus and spotted fever group rickettsiae. The true scale of Rickettsia and Coxiella genera remain to be determined.

Alphaproteobacteria↗
PubMed1994

Q fever serology: cutoff determination for microimmunofluorescence.

Q fever, a worldwide zoonosis caused by Coxiella burnetii, lacks clinical specificity and may present as acute or chronic disease. Because of this polymorphism, serological confirmation is necessary to assess the diagnosis. Although microimmunofluorescence is our reference technique, the cutoff titers that are currently used to make a diagnosis of active or chronic Q fever were determined years ago with limited series of patients and sera. We determined the titers of immunoglobulin G (IgG), IgM, and IgA against both phases (I and II) of Coxiella burnetii. Rheumatoid factor was removed before testing IgM and IgA. We report here the various cutoff titers and the kinetics of antibody development from 2,218 first serum samples of patients, among whom 208 suffered from acute Q fever and 53 had chronic Q fever. In active Q fever, we have defined a low cutoff (phase II IgG titer < or = 100) below which the diagnosis cannot be made and would need further confirmation and confirmed a high cutoff (phase II IgG titer > or = 200 and phase II IgM titer > or = 50) over which the diagnosis can be made. For chronic Q fever diagnosis, phase I IgA titers are not contributive despite previous works claiming their usefulness; a phase I IgG titer of > or = 800 is highly predictive (98%) and sensitive (100%). We have also studied the possibility of rejecting or evoking the diagnosis of chronic Q fever by phase II IgG and IgA titers. This method is useful when phase I testing is not available, but the sensitivity remains low (57%).

Acute Disease↗
PubMed1994

Serological response of patients suffering from primary and recrudescent typhus: comparison of complement fixation reaction, Weil-Felix test, microimmunofluorescence, and immunoblotting.

Microimmunofluorescence and Western immunoblotting were compared with the classical complement fixation reaction and the Weil-Felix test to study the serological responses of patients to Rickettsia prowazekii and both Proteus vulgaris OX19 and OX2 during primary and recrudescent typhus infections. The serological response to R. prowazekii was found to be similar during primary and recrudescent typhus, and all sera examined contained antibodies to the same R. prowazekii cell structures. Immunoglobulin G (IgG) and IgM were found to be the dominant anti-R. prowazekii immunoglobulins in all sera tested and were found to be directed against the 100-kDa protein and the lipopolysaccharide. IgA antibodies, when present, were mainly against the 100-kDa protein. For P. vulgaris, IgG antibodies recognized the proteins and lipopolysaccharides of both OX19 and OX2 serotypes; IgM antibodies were directed against the P. vulgaris OX2 lipopolysaccharide. In addition, donor blood sera, which were negative by microimmunofluorescence, were found to contain IgG immunoglobulins reacting with R. prowazekii protein antigens of 135, 60, and 47 kDa by western immunoblotting.

Adult↗
PubMed1994

Serologic diagnosis of human monocytic ehrlichiosis by immunoblot analysis.

Human monocytic ehrlichiosis is caused by Ehrlichia chaffeensis, an intracellular bacterium probably transmitted by the tick Amblyomma americanum in the United States. Despite its lack of specificity in discriminating among infections by closely related Ehrlichia spp., immunofluorescence assay (IFA) is the most frequently used serological diagnostic method. To improve the specificity of the serological diagnosis, we compared antigenic profile of E. canis and E. chaffeensis antigen with homologous and heterologous sera, searching for the specificity of the presence of low-molecular-weight proteins. Western immunoblot analysis of IFA-positive human sera revealed 27- and 29-kDa proteins which are not found in E. canis IFA-positive sera from dogs. IFA-positive sera from dogs revealed a low-molecular-weight group of proteins (20 to 28 kDa) which were not found in human E. chaffeensis-positive sera except for a weak band at 22 kDa. The presence o antibodies directed against the 27- and 29-kDa proteins on Western blots is specific for E. chaffeensis infection, and we suggest that the Western blot might complete IFA in cases with low positive predictive value.

Animals↗
PubMed1994

Cytopathic effect, plaque formation, and lysis of Ehrlichia chaffeensis grown on continuous cell lines.

Ehrlichiae are strict intracellular bacterial pathogens that parasitize leukocytes or other blood cells. Only six agents of the tribe Ehrlichieae, namely, Cowdria ruminantium, Neorickettsia helminthoeca, Ehrlichia risticii, Ehrlichia sennetsu, Ehrlichia canis, and Ehrlichia chaffeensis, have been adapted to growth in continuous cell lines. E. chaffeensis, the agent of human ehrlichiosis, has been cultured only in a cell line of canine origin. We adapted purified cell-free E. chaffeensis for growth in human embryonic lung (HEL) fibroblasts (HEL 299), green monkey kidney cells (Vero), and a human cervical epithelioid carcinoma (HeLa) cell line. We observed a cytopathic effect with both Vero cells and HEL cells and plaque formation with cellular lysis when infected Vero cells were cultured in agar. Human fibroblasts are already commonly used for the isolation of viruses, coexiellae, and rickettsiae. Furthermore, the capability of these cells to support the growth of ehrlichiae suggests that they may be useful for primary isolation of ehrlichiae as well. The cytopathic effect produced in Vero or HEL cells offers a very helpful indicator of the infection. Plaque formation in Vero cells is a new phenomenon not yet reported for ehrlichiae and will allow the titration of inocula and clonal purification of this bacterium.

Adaptation, Physiological↗
PubMed1994

Differentiation among spotted fever group rickettsiae species by analysis of restriction fragment length polymorphism of PCR-amplified DNA.

Restriction fragment length polymorphism (RFLP) analysis of PCR-amplified genes was used to study spotted fever group (SFG) rickettsiae, extending the previous work of Regnery et al. (R.L. Regnery, C.L. Spruill, and B.D. Plikaytis, J. Bacteriol. 173:1576-1589, 1991). Twenty-six strains of SFG rickettsia were studied, including several recognized species which have never been studied (R. parkeri, R. helvetica, and R. japonica) as well as strains which are not currently classified. Two previously used primer pairs derived from the R. prowazekii citrate syntase gene and the R. rickettsii 190-kDa protein antigen gene were studied, as were primer pairs obtained from the R. rickettsii 120-kDa protein antigen gene. By using three amplifications and three enzyme digestions, it was possible to differentiate between almost all of the known SFG rickettsia species and to differentiate between several strains of the R. conorii complex. Two human pathogens, "R. africae" and the Israeli tick typhus rickettsia, were first separated by using BG-12 pair primer amplification and then RsaI restriction endonuclease digestion. The proposed simplified model of identification may be useful in studying the geographical distributions of SFG rickettsiae.

Animals↗
PubMed1994

Isolation and characterization by immunofluorescence, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western blot, restriction fragment length polymorphism-PCR, 16S rRNA gene sequencing, and pulsed-field gel electrophoresis of Rochalimaea quintana from a patient with bacillary angiomatosis.

Rochalimaea quintana was isolated from the blood of a French human immunodeficiency virus-infected patient with bacillary angiomatosis. The isolate showed the typical growth characteristics of Rochalimaea species and was inert when typical biochemical testing was used. The purpose of the present work was to characterize and compare this new isolate with reference strains of R. quintana, Rochalimaea vinsonii, and Rochalimaea henselae by using immunofluorescence, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blot (immunoblot), restriction fragment length polymorphism-PCR of the citrate synthase gene, 16S rRNA gene sequencing, and pulsed-field gel electrophoresis. SDS-PAGE, Western blot, restriction fragment length polymorphism-PCR with TaqI enzyme, and 16S rRNA gene sequencing could differentiate the three Rochalimaea species and allowed characterization of the French isolate as R. quintana. However, identification of the Rochalimaea isolate to the species level was more easily obtained by immunofluorescence with specific murine antisera. Pulsed-field gel electrophoresis allowed differentiation of the French R. quintana isolate from R. quintana Fuller and may serve as an epidemiological tool.

AIDS-Related Opportunistic Infections↗
PubMed1994

Chronic Q fever in hemodialysis patients.

We describe two cases of chronic Q fever in hemodialysis patients (HD). In the first case, we discovered chronic Q fever when looking for the cause of an unexplained fever. In the second case, Q fever was diagnosed in a patient who complained of an unexplained shoulder arthritis. To our knowledge these are the first reported cases of chronic Q fever in HD.

Adult↗
PubMed1994

Isolation and identification of a rickettsial strain related to Rickettsia massiliae in Greek ticks.

Adult ticks were collected in a rural area of central Greece in order to isolate and identify rickettsiae. A hemolymph test using Gimenez staining was used for detection, while simultaneous isolation was performed using the shell-vial technique. Serologic, antigenic, and genomic characterization of the isolates was achieved by microimmunofluorescence, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP), and pulsed-field gel electrophoresis (PFGE), respectively. Although none of the 242 collected ticks was positive by the hemolymph test, one rickettsial isolate, designated GS, was obtained by the shell-vial technique. This isolate originated from a female Rhipicephalus sanguineus. Microimmunofluorescence serologic typing by the method of Philip and others demonstrated that GS belongs to the same serotype as the recently isolated Rickettsia massiliae (Mtu1). Protein analysis by SDS-PAGE and immunoblotting by Western blot revealed similar profiles between the two rickettsiae. Using Alu I, Rsa I, and Pst I restriction endonucleases in PCR-RFLP analysis, GS and R. massiliae were found to possess identical restriction sites. However, PFGE showed differences when the two genomes were digested with Bss HII and Sma I restriction endonucleases, in spite of their equal size. In conclusion, the first rickettsial isolation in Greece was found to be antigenically identical and genotypically close to the French isolate R. massiliae, despite small differences showed by PFGE.

Animals↗