Jacques Minet

Association of Anti–Porphyromonas gingivalis Antibody Titers With Nonsmoking Status in Early Rheumatoid Arthritis: Results From the Prospective French Cohort of Patients With Early Rheumatoid Arthritis

To investigate the possible link between Porphyromonas gingivalis infection and rheumatoid arthritis (RA), according to antibody profile, genetic and environmental factors, and RA severity.

Anti‐Porphyromonas gingivalis antibodies titres are associated with non‐smoking status in early rheumatoid arthritis: Results from the ESPOIR cohort

To investigate the possible link between Porphyromonas gingivalis infection and rheumatoid arthritis (RA), according to antibody profile, genetic and environmental factors, and RA severity.

Direct enumeration of injured Escherichia coli cells harvested onto membrane filters

Abstract Four methods testing either biosynthesis capacity (Direct Viable Counts), respiratory activity (CTC and XTT reduction assays), or membrane integrity (LIVE/DEAD® BacLight™ VIABILITY kit) were performed to enumerate E. coli injured cells previously harvested onto 0.2-μm black membranes. Some of them remained viable but were no longer culturable when exposed to hyperosmotic or oxidative stresses. The damaged cellular functions were dependent on the stress applied, and the results provided by these methods (except the XTT reduction method which is not sensitive enough), gave information on cell behaviour to one stress, and on the different cellular targets of this stress. The osmotic shock in artificial seawater led to moderate plasma membrane damage (0.8 log reduction in counts determined with the LIVE/DEAD® BacLight™ VIABILITY kit after 5 days in seawater), and to similar reductions of respiration and elongation capacities (2.7 log reduction of CTC counts, and 2.6 log reduction of DVC counts, respectively). After a 30-min oxidative stress induced by peracetic acid (8 mg l−1), the plasma membranes remained intact (no reduction of LIVE/DEAD® BacLight™ VIABILITY counts), and respiration was less impaired than elongation capacity (2.1 log reduction of CTC counts and 3.1 log reduction of DVC counts, respectively).

Proteins variations in Listeria monocytogenes exposed to high salinities.

Listeria monocytogenes Scott A grown in the minimal chemically defined medium M6LT was challenged to a concentration of either 35 or 65 g l(-1) of NaCl for 1 h in the presence of a [35S]cysteine-[35S]methionine labelling mix. The protein patterns were analysed by 2D-electrophoresis in the two conditions and isoosmotic condition (5 g l(-1) of NaCl in M6LT). A great number of proteins which were synthesized under isoosmotic conditions were either completely repressed or expressed at a reduced level, at 65 g l(-1) and to a lesser extent at 35 g l(-1) of NaCl. At 35 g l(-1) of NaCl, six proteins were up-regulated, five proteins showed no change in expression level and five were repressed. Among the proteins up-regulated at 35 g l(-1) of NaCl, a single one (18.7 kDa, pI 5.05) was up-regulated at 65 g l(-1) too. We observed 21 proteins which were repressed at 65 g l(-1) of NaCl, among which 11 completely disappeared. Some of the up-regulated proteins have characteristics of molecular weight and isoelectric point close to those of stress proteins reported elsewhere: the protein induced both at 35 and 65 g l(-1) might correspond to a previously proposed universal stress protein of Listeria. Some proteins which were repressed at 65 g l(-1) have molecular weights close to those of virulence proteins.

Prevalence of low-virulence Listeria monocytogenes strains from different foods and environments

Various studies have demonstrated variations in the levels of virulence of different L. monocytogenes strains. In our laboratory, a plaque-forming assay followed by subcutaneous footpad inoculation of mice enabled us to estimate the prevalence of the low-virulence strains. This value fell from 16.3% to 1.7% with bacteria collected before 1994 and after 1997 respectively. This could be related to the modification in 1997 of the reference method EN ISO 11 290-1 of Listeria detection which recommended the use of polymyxin-acriflavine-LiCl-ceftazidime-aesculin-mannitol (PALCAM) medium. The aim of this study was to determine whether the percentage of low-virulence strains detected has changed due to the modification of the detection method recommending the use of the ALOA medium. After analyzing 380 L. monocytogenes strains, no increase in the percentage of low-virulence strains could be detected. The prevalence reached only 2.6% (ten of the 380 strains tested). The low virulence of L. monocytogenes strains was not related to rare serotypes and was also observed in serotypes usually involved in human disease. Low-virulence strains were found in dairy, meat, ready-to-eat products and also in the environment, highlighting the absence of one specific source. These results are discussed in terms of detection methods and the definition of low virulence.

An improved filter method for direct viable count of Salmonella in seawater

The method of Kogure et al. (1984), which employed measurement of enlarged cells in water samples enriched with low concentrations of nutrient, combined with detection by fluorescent antibodies was used to obtain direct viable counts of Salmonella typhimurium. Technical conditions of the method have been optimized for S. typhimurium, i.e., incubation time of 6 h at 37°C and addition of nalidixic acid at a concentration of 12 mg/l. Natural seawater samples with a salinity of 35% wwere inoculated with S. typhimurium at concentrations of 104−105 cells/ml and kept at 4°C up to 60 h. When yeast extract and nalidixic acid were added to the seeded samples, elongated cells could not be detected. Minimal inhibitory concentrations of nalidixic acid were higher for S. typhimurium at full strength seawater salinity (250 mg/l) compared with fresh water (15.6 mg/l). This effect on the direct viable count was eliminated by filtering samples, using 0.2-μm pore size Nuclepore black filters and modifying the procedure. The method developed in this study permitted observation of elongated (viable) cells of S. typhimurium in the full strength seawater samples (17.3–28.3% elongated cells). The method is suitable for conditions in which the salinity of the samples poses a problem in obtaining direct viable counts.

No increased seroprevalence of anti-Yersinia antibodies in patients with type 1 (C282Y/C282Y) hemochromatosis

Systemic infections, such as hepatic abscesses or peritonitis, caused by Yersinia enterocolitica and Yersinia pseudotuberculosis are rare, and many infections are subclinical, even when bacteremic ...