Systèmes de vigilance : Systèmes de surveillance de santé publique

In France, reactions of public health decision makers were done step by step, within a context often marked by crises, such as that of contaminated blood. It resulted the development of multiple vigilance systems. All vigilance systems have in common a public health objective, the necessity to have information on the actions of the system of health and their consequences. In this article, we define a vigilance system as a public health surveillance system, i.e. a finalised information system, built as a continuous process of standardised collection, analysis and diffusion of data, to allow fast decision-making concerning one or more facets of the activities of the health system. We describe the activities of a vigilance system, and specify steps for implementing such a system. The article ends in a proposal for a mode of evaluation common to all vigilance systems.     

Évaluation des performances et de la praticabilité de l'automate de cytobactériologie sysmex UF-100™ pour la prédiction de l'infection urinaire

In three public health routine laboratories, we have evaluated the performance and the usefulness of the automated flow cytometer Sysmex UF-100™ (Sysmex France, Villepinte, France) for urinary sediments. 612 urine specimens were tested for cytobacteriological count using the instrument and compared with conventional manual methods used in these laboratories.With the interpretive cut off values proposed by the manufacturer, the results obtained show 90 % specificity, 80 % sensibility as well as a positive predictive value of 70 % to detect urinary infections by the automated method. The “false negative” rate was only 2,8 %. This can be reduced by decreasing cut off values used to calculate the predictive index of infection (leucocyturia and number of bacteria/ml), without affecting the acceptable rate of « false positive å. The instrument proved to be able to replace the manual method used to analyse urinary sediments, and can significantly reduce the number of cultures performed on non infected samples. It improves standardisation and precision of leucocyte and bacteria counts, significantly reduces time for testing, and optimises the workflow of the laboratories.     

Apport de la biologie moléculaire au diagnostic de la tuberculose

Reducing delays in diagnosing tuberculosis should contribute to lower the lethality and to reduce the transmission. Microscopy examination is an easy to perform and rapid technique, but lacks sensitivity and specificity. Culture and biochemical identification are sensitive and specific, but require two to eight weeks DNA probes performed on solid or liquid media are very efficient for M. tuberculosis complex strains identification. Nucleic acid amplification techniques are available to directly detect the M. tuberculosis complex in clinical samples. Performances are variable. Very good results are obtained with experienced teams who scrupulously follow the specified guidelines.     

Érythropoïétine : comparaison de trois trousses de dosage

The evaluation of two assays of erythropietin allows a comparison with the IRMA coated kit Epo Coatria (Biomérieux). The aim of this work is to present the results obtained in two groups of patients, with the chemiluminescence method (Advantage^® automate) and with the ELISA Quantikine IVD kit in comparison with the IRMA (Biomérieux) coated assay, which is the reference method of the laboratory. The statistic tests show an important overlap between the reference group values and those of the polycytemia group (p = 0,45) with the chemiluminescence test. The correlation between ELISA and IRMA methods is quite good (r² = 0,714) and allows us to ensure the transfer of our results, especially in the case of polycytemia vera.     

Mécanismes et méthodes de détection de la résistance de Staphylococcus aureus aux glycopeptides

For more than 30 years, glycopeptides remained active on Staphylococcus aureus strains. Nevertheless, the emergence of strains resistant to these antibiotics was feared. In the last five years, numerous and diverse glycopeptide-resistant strains were isolated. Two major mechanisms could explain this resistance. Gene transfer from vancomycine-resistant enterococci strains to S. aureus results in the acquisition of a high level resistance to glycopeptides in this species. For the strains with lower susceptibility to glycopeptides, the main mechanism seems to be related to an increased cell wall thickness, which may result in trapping of glycopeptide molecules far from their active sites. High level resistance, because of high minimal inhibitory concentrations, is easily detected in the clinical laboratory. On the other hand, the detection of S. aureus strains with lower susceptibility to glycopeptides is difficult. The E-Test® or the modified population analysis method are sensitive, but difficult to use in routine practice. The development of techniques and culture media allowing a systematic and performing detection is still controversial.