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C Nauciel

Publications and source records attributed to C Nauciel.

At least 19 recordsLinked to original sources
PubMed2002

[Molecular markers in the epidemiologic study of Legionella pneumophila infections].

PURPOSE: Legionnaires' disease is due to the inhalation of contaminated aerosols. The identification of the source of contamination in the aquatic environment is necessary to prevent the occurrence of new cases. A comparative study of clinical and environmental isolates is the basis of epidemiological investigations. CURRENT KNOWLEDGE AND KEY POINTS: Genotypic methods are now mainly used to compare bacterial strains. Some of these methods are based on the electrophoretic separation of DNA restriction fragments. When electrophoretic profile are complex, some fragments can be visualized after hybridization (ribotyping). Large-sized fragments can be separated by pulsed-field gel electrophoresis. Other techniques are based on gene amplification, such as AP-PCR. This technique is easy to perform but its discriminatory power and reproducibility are lower. Some procedures are combining enzymatic cleavage and gene amplification. Finally methods based on the nucleotide sequence analysis of some genes are being evaluated. FUTURE PROSPECTS AND PROJECTS: Techniques enabling the rapid comparison of various Legionella isolates will permit a quick detection of outbreaks and contribute to the identification of the source of contamination.

DNA, Bacterial↗
PubMed2000

Mycobacterium genavense infection in normal and immunodeficient mice.

Mycobacterium genavense is a recently described microorganism causing disseminated infections in AIDS patients. In this study, we investigate its pathogenicity in mice and some mechanisms of the host response to this bacterium. Following an intravenous challenge of 10(6) organisms, M. genavense grew progressively in the spleens and livers of BALB/c and CBA mice over at least an 8-month period. Granulomas were present in the spleens, livers and lungs of the animals. The numbers of bacteria recovered from the spleens and livers were higher in BALB/c (Bcg(s)) than in CBA (Bcg(r)) mice from day 30. The role of the Bcg gene, in the early phase of infection, was supported by the fact that the bacterial load, on day 15, was higher in BALB/c than in the congenic C.D2 (Bcg(r)) mice. The role of T cells in the host response was suggested by the high susceptibility of nude mice to M. genavense infection. In vivo depletion experiments in CBA mice indicated that gamma interferon and both CD4(+) and CD8(+) T cells participate in the containment of the bacterial load.

Animals↗
PubMed1999

Single clonal origin of a high proportion of Legionella pneumophila serogroup 1 isolates from patients and the environment in the area of Paris, France, over a 10-year period.

Arbitrarily primed PCR with three primers and pulsed-field gel electrophoresis were used to characterize a set of 75 clinical Legionella pneumophila serogroup 1 isolates, with no apparent epidemiological link, obtained from 24 hospitals in Paris, France, from 1987 to 1997. Unexpectedly, 25 clinical isolates from 15 hospitals had an identical profile (termed type A) by both methods. The same profile was subsequently found in 16 of 64 randomly selected environmental L. pneumophila serogroup 1 isolates from 15 different sites in the Paris area. There was no evidence of geographic clustering or a peak incidence of type A isolation. Type A has not been found in France outside the Paris area, suggesting that a particular type of L. pneumophila serogroup 1 is specifically present in the Paris water distribution network.

Bacterial Typing Techniques↗
PubMed1998

[Quality of blood salvaged in orthopedic surgery by washing swabs].

OBJECTIVE: To establish the feasibility and safety of recuperating blood absorbed by swabs used during orthopaedic surgery. STUDY DESIGN: Open, prospective study. PATIENTS: Included were children undergoing potentially haemorrhagic orthopaedic surgery for whom intraoperative blood salvage seemed possible. Excluded were those with contraindications for this procedure such as septic surgery and cancer surgery. METHOD: Intraoperative swabs used within the surgical field were collected by a surgical assistant, also in charge of weighing and washing them. The liquid was collected by the aspiration system of a recuperation-washing machine (RWM). The salvaged red blood cells were collected and retransfused at the end of surgery. Several samples of the washing liquid of the swabs and salvaged blood were taken during the procedure. The correlation between the quantity of blood shed and salvaged was calculated. The biological and clinical tolerance of the transfusion was assessed. RESULTS: Twelve patients undergoing surgery for scoliosis have been included. An average of 278 mL of blood were salvaged. In the washed cell concentrates the haematocrit was 54% and the free haemoglobin concentration was 3.84 g.L-1. All the bacteriological tests were negative over the first 24 hours. CONCLUSION: Provided that a strict operatory protocol is followed, this study demonstrates the possibility of recuperating blood from swabs used during major orthopaedic surgery.

Adolescent↗
PubMed1998

Treatment of disseminated Mycobacterium genavense infection in a murine model with ciprofloxacin, amikacin, ethambutol, clarithromycin and rifabutin.

Mycobacterium genavense is a recently described agent which can induce disseminated infections in patients with AIDS. Up to now, no standard approach to treatment has been defined and patients have been treated empirically with antibiotics used for treating infections caused by other nontuberculous mycobacteria. In this study, we compared the effectiveness of ciprofloxacin, amikacin, ethambutol, clarithromycin and rifabutin in the treatment of an animal model of M. genavense infection in C57BL/6 mice. Antimycobacterial treatment was started 4 weeks after an intravenous bacterial challenge and was continued for 30 days. Treated and control mice were killed at days 15 and 30 of treatment and the number of viable bacteria in their spleens was counted. Treatment with clarithromycin (50 mg/kg/day sc) and rifabutin (20 mg/kg/day po) was found to decrease the bacterial counts in the spleens significantly as early as 15 days after the onset of treatment (P < 0.01). The effect of treatment was more pronounced after 30 days of treatment (P < 0.001). Amikacin (25 mg/kg/day sc) and ethambutol (50 mg/kg/day sc) were found to decrease significantly the cfu in the spleens only after 30 days of treatment (P < 0.01). Ciprofloxacin (25 mg/kg/day sc) was ineffective in the experimental conditions used here.

Amikacin↗
PubMed1998

Production of interleukin-12 by murine macrophages in response to bacterial peptidoglycan.

Peptidoglycan (PG), a component of the bacterial cell wall, has various immunomodulating activities, including the capacity to induce delayed-type hypersensitivity reactions to antigens administered in Freund's adjuvant. We report that PG induces interleukin-12 (IL-12) mRNA production and IL-12 secretion by mouse macrophages. The capacity of PG to induce IL-12 production, like its previously reported immunomodulating activities, was dependent on the structure of its peptide subunit. PG from Bacillus megaterium and Staphylococcus aureus induced IL-12 production, whereas PG from Micrococcus luteus and Corynebacterium poinsettiae did not. The ability of most bacterial PGs to induce IL-12 production suggests that they play an important role in triggering host defense mechanisms against bacterial infections.

Adjuvants, Immunologic↗
PubMed1998

[Comparative activity of cefepime, ceftazidime and imipenem in a mouse infection caused by Klebsiella pneumoniae producing a broad spectrum beta-lactamase].

Mice experimentally infected with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strains were injected twice daily for three days with ceftazidime, cefepime, or imipenem (25, 50, or 100 mg/kg/injection). Treatment efficacy was based on five-day survival and on the spleen viable bacteria count 16 hours after the last treatment dose. Under these experimental conditions, ceftazidime showed some activity on strains with low levels of resistance to ceftazidime. Cefepime used in a dose of 50 or 100 mg per injection demonstrated good activity but was slightly less effective than imipenem.

Animals↗
PubMed1997

Lack of resistance to erythromycin, rifampicin and ciprofloxacin in 98 clinical isolates of Legionella pneumophila.

Ninety-eight consecutive clinical isolates of Legionella pneumophila were tested for erythromycin, rifampicin and ciprofloxacin susceptibility. MICs, determined by agar dilution testing, were in the range 0.06-1 mg/L of erythromycin, 0.007-0.015 mg/L of rifampicin and 0.015-0.03 mg/L of ciprofloxacin. No resistance against the antibiotics tested was detected. It is thus likely that therapeutic failures in legionnaires' disease are not related to the emergence of resistance against commonly used antimicrobial agents.

Anti-Bacterial Agents↗
PubMed1997

JC virus detection in the cerebrospinal fluid of AIDS patients with progressive multifocal leucoencephalopathy and monitoring of the antiviral treatment by a PCR method.

Twenty-four cerebrospinal fluid (CSF) samples from 19 AIDS patients with neurological signs were analysed by the polymerase chain reaction (PCR) for the presence of JC virus (JCV). Eleven of the 19 patients tested presented with progressive multifocal leucoencephalopathy (PML). Two specific JCV target sequences were used for the PCR analysis: a sequence specific for the T antigen genes from both BK virus (BKV) and JCV (PCR1) and a sequence specific for the large T antigen gene from JCV (PCR2). The JCV genome was detected in 10 of 11 patients with PML by the PCR1 method and in all 11 patients by the PCR2 method. With samples from the eight patients without PML, one positive result was obtained with the PCR1 method and this sample and another gave positive results with PCR2. Multiple CSF samples were collected from three patients with PML at different times, including after intrathecal cytarabine treatment, and were tested by the PCR2 method for the presence of the JCV genome. The PCR result became negative for two of the three patients during the cytarabine treatment. However, the absence of a PCR signal was not associated with clinical improvement in these patients. The PCR method is useful for the detection of JCV in CSF samples and in the diagnosis of PML. However, the application of PCR for monitoring the effect of treatment remains to be established.

AIDS-Related Opportunistic Infections↗
PubMed1997

Th1 response in Salmonella typhimurium-infected mice with a high or low rate of bacterial clearance.

Previous studies have shown that the capacity to clear an attenuated strain of Salmonella typhimurium after the second week of infection varies widely among mouse strains. Bacterial clearance is mediated by CD4+ T cells and is regulated in part by the H-2 complex. The aim of the present study was to compare the patterns of cytokine mRNA expression in the spleens of C57BL/6 (H-2b) and CBA (H-2k) mice, which exhibit a low and a high rate of bacterial clearance, respectively. A transient increase in interleukin-12 (IL-12) mRNA levels was found in both mouse strains. Gamma interferon (IFN-gamma) gene expression was higher and more sustained in C57BL/6 than in CBA mice. No increase in IL-4 mRNA was detected. A transient increase in IL-10 mRNA was found in C57BL/6 mice. Separation of spleen cells into CD4+ and CD4- fractions showed that CD4+ T cells produced the bulk of IFN-gamma in both mouse strains and of IL-10 in C57BL/6 mice. Infection of H-2 congenic mice induced a higher level of IFN-gamma mRNA expression by CD4+ T cells in mice with a low rate of clearance (H-2b) than in mice with a high rate of clearance (H-2q). Treatment of infected C57BL/6 mice with anti-IFN-gamma or anti-CD4 monoclonal antibodies indicated that IFN-gamma participates in resistance in the early phase of infection, but not in bacterial clearance, and that CD4+ T cells mediate bacterial clearance during the 3rd week of infection. Taken together, these results suggest that defective bacterial clearance in H-2b mice is not linked to defective IFN-gamma production and that CD4+ T cells mediate bacterial clearance by an IFN-gamma-independent mechanism.

Animals↗
PubMed1996

[Legionnaires' disease in the Paris area: epidemiology and mortality. Apropos of a series of 81 culture-positive cases].

OBJECTIVES: Evaluate etiological circumstances and prognosis in Legionnaires' disease. METHODS: A series of 81 culture-proven cases of Legionnaires' disease was collected in the Paris area between 1989 and 1994. RESULTS: Direct immunofluorescence assay was positive for Legionella pneumophilia in 48% of the cases. Serogroup 1 was isolated in 88% of the cases. The median age of the patients was 51 years and 74% were males. Infection was nosocomial in 28% of the cases. Immunosuppression was present in 45% of the patients (transplantation, cancer, leukemia). Among the immunosuppressed patients, 7 were HIV-infected. Mortality due to legionellosis reached 27%. This high mortality was probably related to patient selection criteria. CONCLUSION: Mortality from Legionnaires' disease remains high as confirmed in this series.

AIDS-Related Opportunistic Infections↗
PubMed1996

Beneficial effect of Salmonella typhimurium infection and of immunoglobulins from S. typhimurium-infected mice on the autoimmune disease of (NZB x NZW) F1 mice.

Various infections can precede or aggravate autoimmune diseases. Yet a beneficial effect of infection has also been described an various mechanisms have been postulated to explain this effect. The aim of this study was to examine the hypothesis that infection can have an immunoregulatory effect on the autoimmune process via the increased production of natural polyreactive antibodies. The effect of Salmonella typhimurium infection on the lupus-like disease of (NZB x NZW)F1 (B/W) mice was therefore studied. The effect of IgM and IgG preparations isolated from the serum of S. typhimurium-infected C57B1/6 and CBA mice on the autoimmune disease of B/W mice was also tested. C57B1/6 and CBA mice were chosen because they are respectively genetically susceptible and resistant to S. typhimurium infection and they differ in their antibody response during the early phase of infection. CBA mice can mount a specific anti-bacterium antibody response, whereas C57B1/6 mice present increased production of polyreactive antibodies. The infection effect was evaluated on several disease parameters, i.e. survival, incidence of high grade proteinuria and serum IgM and IgG antibody activity directed against a panel of autoantigens. Our main findings were: (i) infection of B/W mice with an attenuated strain of S. typhimurium delayed the course of the autoimmune disease when performed before the appearance of autoimmune symptoms; and (ii) IgM and IgG preparations from S. typhimurium-infected C57B1/6 mice had a similar effect whereas the IgM and IgG preparations from infected CBA mice, as well as from normal C57B1/6 and CBA mice, were ineffective. These results suggest that S. typhimurium infection can beneficially influence the development of the autoimmune disease of B/W mice. The immunoregulatory effect of the infection seems to be related at least partially, to the increase of a particular population of antibodies, the polyreactive antibodies.

Animals↗
PubMed1996

Gamma interferon and interleukin-10 gene expression in innately susceptible and resistant mice during the early phase of Salmonella typhimurium infection.

Previous studies have shown that gamma interferon (IFN-gamma) plays a major role in natural resistance to Salmonella typhimurium during the early phase of infection. To assess whether the level of natural resistance in mice is related to the level of IFN-gamma gene expression, we compared IFN-gamma mRNA levels by means of reverse transcriptase-PCR in the spleens of genetically susceptible Itys (C57BL/6 and BALB/c) and resistant Ityr (CBA and DBA/2) mice during the first 5 days of infection. The mRNA expression of interleukin-10 (IL-10), a cytokine which antagonizes IFN-gamma effects, was also investigated. Mice were infected with 10(3) CFU of the virulent strain S. typhimurium C5, a dose which is lethal within a week for susceptible mice only. IFN-gamma mRNA increased to similar levels in both susceptible and resistant mice, suggesting that susceptibility to S. typhimurium infection is not related to defective IFN-gamma gene expression. In contrast, IL-10 mRNA reached much higher levels in susceptible than in resistant mice. Similar results were found in Ity congenic mice, confirming a link between the presence of the Itys allele and a high level of IL-10 gene expression during infection. High levels of IL-10 mRNA in susceptible mice correlated with high IL-10 serum levels (on day 5), whereas IL-10 was not detectable in the sera of resistant mice. However, administration of neutralizing anti-IL-10 monoclonal antibodies did not modify the course of infection. To evaluate the influence of bacterial multiplication on IL-10 mRNA expression, susceptible mice were infected with an attenuated strain of S. typhimurium. This strain induced a low level of IL-10 mRNA expression. When susceptible mice were immunized with an attenuated strain and challenged with the virulent strain, they inhibited the growth of the challenge bacteria and exhibited a low level of IL-10 mRNA. In contrast, when resistant mice were infected with a high (lethal) dose of the virulent strain, they exhibited a high level of IL-10 mRNA. Taken together, these results indicate that the level of IL-10 gene expression correlates with the level of bacterial multiplication in the organs and that the high level of IL-10 mRNA in Itys mice is a consequence rather than the cause of their susceptibility to S. typhimurium infection.

Animals↗
PubMed1995

[Defense mechanisms against bacteria of intracellular development].

Intracellular bacteria are not inhibited by antibodies. Therefore the main mechanisms of resistance against these pathogens are the influx and activation of mononuclear phagocytes by the synergistic interaction of gamma-interferon and tumour necrosis factor. During the early phase of infection, gamma-interferon is produced by IL-12-activated natural killer cells (IL-12 being mainly produced by macrophages). In the later phase of infection acquired immunity is T-cell-mediated and involves the Th1 CD4+ subpopulation. These cells produce gamma-interferon when triggered by antigen. There is a complex network of interactions among cytokines. Some cytokines act synergistically to enhance resistance to infection, yet antagonistic interactions can sometimes occur.

Animals↗
PubMed1995

[Evaluation of an ELISA technique for the serodiagnosis of legionnaires' disease].

The presence of anti-Legionella antibodies was studied comparatively in 81 sera with a commercially available ELISA kit (containing serogroups 1 to 6 as antigens) and the indirect immunofluorescence assay (IFA) with serogroup 1. The values obtained with the ELISA method were converted into immunofluorescence titers by using standard sera. Results of both methods were concordant in 83% of the sera when a cutoff value of 1/128 was used, and in 88% of the sera when the cutoff value was 1/128 for IFA and 1/256 for ELISA. In 6 other patients infected by serogroups other than 1, antibodies were detected in 5 cases with ELISA and in none with IFA.

Enzyme-Linked Immunosorbent Assay↗