[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.

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.

Molecular typing of Legionella pneumophila serogroup 1 isolates from patients and the nosocomial environment by arbitrarily primed PCR and pulsed-field gel electrophoresis.

The ubiquity of Legionella pneumophila in aquatic habitats means that epidemiological evaluation is important for the investigation and control of nosocomial outbreaks of legionellosis. Pulsed-field gel electrophoresis (PFGE) of chromosomal DNA following digestion with SfiI is considered to be one of the most discriminative methods for detecting DNA polymorphisms amongst L. pneumophila serogroup 1 (Lp1) isolates.

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.

[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.

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.

[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.

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.

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.

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.

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).

[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.

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.

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.

[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.

[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).

Comparison of polymerase chain reaction and non-radioactive hybridization techniques for the identification of Mycobacterium avium strains.

A polymerase chain reaction able to amplify specifically a 205-base-pair DNA fragment of Mycobacterium avium genome was used and compared to a nonradioactive hybridization assay (AccuProbe) and to conventional biochemical identification. The PCR approach to diagnosis of M. avium infection is a valid diagnostic alternative to the more classical procedures.

Influence of mouse genotype and bacterial virulence in the generation of interferon-gamma-producing cells during the early phase of Salmonella typhimurium infection.

Interferon-gamma (IFN-gamma) is known to play a major role in resistance to Salmonella typhimurium infection. In this study, the IFN-gamma production in spleens of mice infected with S. typhimurium was analysed at the single cell level using an ELISPOT method.

Evaluation of commercial amplification kit for detection of Legionella pneumophila in clinical specimens.

A commercial kit (EnviroAmp) designed to detect the DNA of Legionella species in environmental water samples using PCR and reverse dot hybridization was applied to clinical specimens. Results correlated well with culture for bronchoalveolar lavages. In addition, this test was easy to perform and showed good sensitivity.

Molecular epidemiology of Legionella pneumophila serogroup 1 by ribotyping with a non-radioactive probe and PCR fingerprinting.

Hybridization with acetylaminofluorene-labelled 16 + 23 S rRNA from Escherichia coli was used to detect DNA polymorphism among Legionella pneumophila serogroup 1 isolates. Isolates from unrelated patients showed at least four different rRNA restriction patterns, whereas those from related patients showed a single pattern. Amplification of genomic regions with an arbitrary primer by polymerase chain reaction was used to further analyze the isolates.