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Enterococci are commensal bacteria of Humans predominantly encountered in the digestive tract. Despite their beneficial activity for their host, these microorganisms became the second leading bacterial cause of hospital acquired infections in France for last decades. Some studies showed that the central metabolism is a critical factor for microorganisms infection process. In this study, we worked on the characterisation of metabolisms of the different glucose polymers maltodextrins and gentiobiose in Enterococcus faecalis. The maltose and maltodextrins utilization is coordinated in this bacterium transcriptionally by the MalR repressor. The MalR activity is rapidly modulated by the inducer maltose and by the co repressor P Ser HPr which strengthens the MalR DNA binding. The metabolism of long maltodextrins is also repressed by the pleiotropic regulator CcpA in complex with its essential cofactor P Ser HPr in presence of glucose. The Catabolite repression of the operon genBA, involved in metabolism of the β glycoside gentiobiose, is assumed by CcpA in presence of glucose. This operon genBA allows the gentiobiose uptake with a PTS and its catabolism by a hydrolase. The expression of this latter operon requires both the GenR transcriptional activator and the inducer gentiobiose 6' P., Les entérocoques sont des bactéries commensales de l'Homme majoritairement rencontrées dans le tractus digestif. En dépit du caractère bénéfique pour leur hôte, ces microorganismes sont retrouvés au deuxième rang des bactéries responsables d'infection nosocomiales en France ces dernières décennies. Diverses études tendent à montrer que le métabolisme énergétique constitue un facteur crucial pour le processus infectieux des microorganismes. Lors de ce travail, nous nous sommes intéressés à l'étude des métabolismes de différents polymères de glucoses chez Enterococcus faecalis : les maltodextrines et le gentiobiose. L'utilisation du maltose et des maltodextrines est, chez cette bactérie, directement coordonnée au niveau transcriptionnel par le répresseur MalR. L'activité de ce régulateur est rapidement modulée par le maltose qui représente l'inducteur du système et par un corépresseur protéique : la protéine P Ser HPr qui, à l'inverse, favorise la répression exercée par MalR. Le métabolisme des maltodextrines complexes, mais pas le métabolisme du maltose, est également réprimé par le régulateur pléiotrope CcpA en coordination avec son cofacteur P Ser HPr en présence de glucose. La répression catabolique de l'opéron genBA, impliqué dans le métabolisme du β glycoside gentiobiose, est aussi assurée par ce régulateur CcpA en présence de glucose. Cet opéron genBA est responsable de l'import du gentiobiose par un PTS ainsi que de son catabolisme grâce à une hydrolase. L'expression de cette structure opéronique nécessite la présence de l'activateur transcriptionnel GenR actif en présence de l'inducteur gentiobiose 6' P.

Enterococci are microorganisms with a remar- kable ability to adapt to their environment. Two species have a significant clinical implication, Enterococcus faecalis and Enterococcus faecium. The risk factors for colonization and infection must be recognized, including prior treatment with antibiotics such as cephalosporins or quinolones. Because of their native resistance to several classes of antibiotics and the increase of acquired resistance to penicillins, the initial empiric treatment of a severe infection in a patient at risk of enterococcal infection often includes a glycopeptide. A restriction in the empirical use of cephalosporins or quinolones and a targeted antibiotic therapy following receipt of the antibiogram are essential to prevent the emergence of enterococcal strains and especially vancomycin-resistant enterococci.

Les bactéries lactiques (LAB) sont capables de fermenter de nombreux produits animaux et végétaux, produisant entre autres des acides, des composés aromatiques comme le diacétyl et des polysaccharides participant à l’aspect, la texture et la flaveur du produit fermenté. Pour les produits laitiers, les LAB fermentant le lait peuvent être apportées par le lait, et/ ou les récipients servant à la fermentation, et/ou des levains. L’industrialisation croissante de la production de produits laitiers fermentés conduit à utiliser de plus en plus des levains. C’est le cas en Algérie. Dans ce contexte, ce travail a pour objectif l’obtention d’un souchier de cocci lactiques mésophiles sélectionnés et adaptés à la fermentation de lait pour produire des laits fermentés type Lben et des fromages frais Jben, deux produits fermentés traditionnellement consommés en Algérie.

Ce travail porte sur l’analyse de 63 échantillons de blanc d’oeuf dont 30 de blanc cru et 33 de blanc pasteurisé. Les analyses réalisées sont le dénombrement de la flore total à 30°C, l’étude des capacités d’altération des isolats après inoculation (de 3 à 5 log UFC/mL) dans de la crème anglaise et incubation à 10 °C pendant 21 jours. Les isolats altérants la crème anglaise sont ensuite identifiés par séquençage de l’ADN 16S puis caractériser selon leurs capacités à produire des protéases, lipases et amylases sur des milieux gélosés à base de crème anglaise. La révélation de ces activités enzymatiques sont basés sur la présence et la mesure d’un halo d’éclaircissement, la fluorescence due à la rhodamine B, ou la présence d’un halo après coloration au lugol pour les activités protase, lipase et amylase respectivement. Les résultats montrent que près de 80% des échantillons de blanc analysés étaient contaminés avec des niveaux de populations autour de 2±1,6 et 0,94±0,8 log UFC/mL du blanc cru et pasteurisé respectivement. L’ensemble des isolats étaient capables d’altérer la crème anglaise à 10 °C. Cette altération se caractérise par des niveaux de populations autour de 9,3 log UFC/ml, une diminution du pH, un épaississement, une apparition d’un déphasage, et une présence de bulles ou trous ainsi que des bruits à l’ouverture du tube dus à la production de gaz. La présence d’un de ces critères d’altération, variant selon les genres identifiés, a permis de distinguer 17 profils d’altération. L’identification de bactéries d’altération, a montré une prépondérance des genres Enterobacter et Escherichia dans le blanc d’oeuf cru et d’Enterococcus dans le blanc d’oeuf pasteurisé. Les autres genres identifiés sont Yersinia, Rahnella, Salmonella, Pantoae, Pseudomonas et Bacillus dans le cru et des genres tels que Enterococcus, Enterobacter, Escherichia, Serratia, Shigella et Klebsiella communs aux 2 types de blanc d’oeuf. L’ensemble des isolats testés est capable de produire des protéases mais à des niveaux variables (épaisseurs des halos de 1 à 6,2 mm). Soixante pourcent, cent pourcent et quatre-vingt pourcent des isolats présentent des activités lipase, protéase et amylase respectivement. Ce travail souligne l’importance de la maitrise des flores bactériennes issues des ovoproduits qui sont capable d’altérer des produits finis tels que des desserts réfrigérés., This work focuses on the analysis of 63 liquid egg white samples, including 30 raw and 33 pasteurized samples. The performed analysis are the total enumeration flora at 30 °C, the spoilage abilities of the isolates after inoculation (3 to 5 log CFU/mL) and incubation in the custard cream at 10 °C for 21 days. The spoilage isolates were then identified by DNA 16S sequencing and characterized according to their ability to produce proteases, lipases and amylases on agar custard based media. The revelation of these enzymatic activities are based on the presence and translucent halo extent, fluorescence due to rhodamine B, or the presence of a halo after Lugol staining for the protease, lipase and amylase activities respectively. The results show that about 80 % of egg white samples were contaminated with population levels around 2±1,6 and 0,94±0,8 log CFU/mL in raw and pasteurized white respectively. All isolates were able to spoil custard cream at 10 °C. The custard cream spoilage is characterized by a bacterial growth reaching level as high as 9,3 log CFU/mL, a decrease in the pH, thickening, an appearance of a phase shift and the presence of bubbles or holes as well as noises opening tube due to gas production. The presence of these alteration criteria, varying genera identified, allowed to distinguish 17 alteration profiles. The identification of spoilage bacteria showed a preponderance of Escherichia and Enterobacter in raw egg white and Enterococcus in the pasteurized one. Other identified types are Yersinia, Rahnella, Salmonella, Pantoae, Pseudomonas and Bacillus exclusively found in raw egg white and Enterococcus, Enterobacter, Escherichia, Serratia, Shigella and Klebsiella common to the two types of egg white. All isolates tested can produce proteases but at varying levels (thicknesses halos 1 to 6,2 mm). Sixty percent, one hundred percent and eighty percent of the isolates have lipase, protease and amylase activities, respectively. This work highlights the importance of controlling the bacterial flora from egg products which are able to spoil finished products such as chilled desserts.

Contamination of aquatic environments by antibiotics and antibiotic-resistant faecal bacteria is a great concern at the worldwide scale. Discharges of WWTP and runoff or leaching of soils are the main pathways for inputs of these contaminants in surface water. In order to better understand the fate of antibiotics and faecal bacteria populations (Escherichia coli, Enterococcus), these contaminants have been studied along two continuums: (i) medical center - WWTP - river and (ii) cattle farm - urban area. A multi-residue chemical methodology (LC/MS/MS) was developed to detect low concentrations (ng.L-1) of 34 antibiotics in water along the two continuums. Together with these chemical analyses, the structures of faecal bacteria were characterized by antibiotic resistance, distribution of phylogroups A, B1, B2, D, occurrence of integrons, virulence factors for E. coli; and diversity of species, antibiotic resistance and associated resistant genes for Enterococcus. The study of the two continuums has shown that compounds found in rivers were not the most prescribed (penicillins), but the more enduring molecules (quinolones, sulfonamides, macrolides). However, antibiotic concentrations (1ng.L-1 to 100ng.L-1) are insufficient to exert a selective pressure on antibiotic-resistant bacteria. Land use, vicinity of contamination sources and farm practices have an impact on (i) levels of contamination by antibiotics and antibiotic-resistant faecal bacteria, (ii) the structure of E. coli and Enterococcus populations in water. Strains of E. coli and Enterococcus from hospital origin have disappeared along the continuum in favor of other well-adapted strains. First assays of modeling using the hydrological model GR have shown the significance of E. coli fluxes during recurrent runoff periods (winter) on a watershed submitted to a main human pressure., La contamination des environnements aquatiques par les antibiotiques et les bactéries antibio-résistantes est une préoccupation majeure à l'échelle mondiale. Les rejets de stations d'épurations (STEPs) et les ruissellements ou lessivages de sols sont les principales voies d'entrées de ces contaminants dans les eaux de surface. Afin de mieux comprendre le devenir des antibiotiques et des populations bactériennes indicatrices de contamination fécale (Escherichia coli, Enterococcus), ces contaminants ont été étudiés le long de deux continuums : (i) centre de soins - STEP - rivière et (ii) exploitation bovine - zone urbaine. Le développement d'une méthode analytique multi résidu (LC/MS/MS) a permis de détecter les concentrations de 34 molécules d'antibiotiques dans les eaux des deux continuums pour des valeurs seuils de l'ordre du nanogramme par litre. En parallèle à ces analyses chimiques, la structure des populations de bactéries fécales isolées des eaux ont été caractérisées sur la base de l'antibio-résistance, la distribution des groupes phylogénétiques A, B1, B2 et D, l'occurrence d'intégrons, des facteurs de virulence pour E. coli ; et de la diversité d'espèces, des profils de résistance aux antibiotiques et des gènes codant la résistance pour Enterococcus. L'étude des deux continuums indique que les antibiotiques retrouvés ne sont pas les antibiotiques majoritairement prescrits (pénicillines), mais les molécules les plus stables dans les eaux (quinolones, sulfamides, macrolides). Toutefois les concentrations (1ng.L-1 à 100ng.L-1) sont insuffisantes pour exercer une pression de sélection sur les bactéries antibio-résistantes. L'usage des sols, la proximité des sources et les pratiques d'élevage ont un impact sur (i) les niveaux de contamination en antibiotiques et bactéries fécales, et (ii) la structure des populations d'E. coli et d'Enterococcus circulantes dans les eaux. Des souches d'E. coli et d'Enterococcus d'origine hospitalière disparaissent le long du continuum au profit d'autres souches mieux adaptées à l'environnement. Des premiers essais de modélisation à l'aide du modèle conceptuel GR montre également l'importance des flux d'E. coli antibio-résistantes lors des périodes de ruissellements fréquents (hiver) à l'échelle d'un bassin versant dont l'occupation des sols est soumis à une pression humaine majoritaire.

Triclocarban is an antiseptic of the anilide family. Its antibacterial activity was re-assessed in vitro against various susceptible and antibiotic resistant staphylococcus, streptococcus, and enterococcus strains. The results of this study show that, in vitro, the effectiveness of triclocarban antibacterial is maintained at very low MICs ranging from 0.5 to 8 mg/L for the various resistant strains studied. Triclocarban remains still very effective for the treatment of either initially bacterial skin and mucosal infections, or skin and mucosal at risk of super infection.

Antibiotic revolution changed the course of modern medicine, by decreasing mortality due to bacterial infections. However, bacteria have developed several ways of resistance against all antibiotics used. In view of the rise of resistance and of its dissemination to different bacterial families, new effective antibiotics are scare and the return in the pre-antibiotic era seems to be a reality for some parts of the world. This review revises the worrying phenomenon of antibiotic resistance focusing on some examples of "superbugs", which represent a daily challenge for the medical profession, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended spectrum s-lactamae-producing Enterobacteriaceae as well as carbapenem-resistant Pseudomonas aeruginosa. Facing the emergence of the multiresistant strains, the priority is obviously to control the spread of these microorganisms. It is only through the prudent use of antimicrobial drugs and the introduction of new and effective antibiotics that the antibiotic resistance will be slowed down and that we continue to treat bacterial infections.

Enterococci are responsible for various community- and hospital-acquired infections. Glycopeptides (vancomycin and teicoplanin) are active against these microorganisms by inhibiting cell wall synthesis through binding to cell wall precursors. Enterococcus faecium has developed multidrug resistance, including resistance to glycopeptides. Resistance to glycopeptides is due to the acquisition of an operon of genes cooperating to synthesize precursors devoid of affinity for the glycopeptides. Outbreaks were recently reported in hospital settings. These outbreaks were due to E. faecium isolates belonging to an hospital-adapted clonal complex (CC17) characterized by high level resistance to ampicillin and fluoroquinolones and frequently containing virulence factors. Outbreaks may be controlled by appropriate measures and new antibiotics are available in therapy. However, spreading of clonal strains adapted to hospitals require close surveillance.

Vancomycin-resistant enterococci (VRE) are major nosocomial pathogens in many countries. VRE can spread rapidly, mostly by cross-transmission through hands of healthcare workers, leading to outbreaks. Moreover, VRE have the possibility to transfer vancomycin resistance genes to other Gram-positive organisms.We conducted a 9-month prospective study to demonstrate the effectiveness of "contact" precautions to prevent the spread of VRE in a long-term care facility.Six patients with VRE colonisation were admitted in an 80-bed long-term care facility. The following interventions were implemented to prevent the spread of VRE: gathering patients with VRE colonisation in the same unit, reinforcement of hand hygiene practices, "contact" precautions, reduction of some antibiotics and extensive screening of VRE carriers and contact patients by rectal swabs.There was no secondary case of VRE colonisation. Screening tests converted from positive to negative in four of the six patients.Compliance with hand hygiene recommendations and "contact" precautions can prevent the spread of VRE in a long-term care facility.

The monitoring of infection by glycopeptide-resistant enterococci (GRE) is one of the main elements of hospital hygiene policy. It involves systematic rectal swabs in clinics at risk (asymptomatic carriage).We compare two GRE screening methods and evaluate a new kit associating multiplex PCR and hybridization (Génotype(®) Enterococcus, Hain Lifescience) on a panel of 448 samples collected over a 4-month period.The first method is based on direct inoculation of the sample; the second one involves a preliminary enrichment phase followed by molecular diagnosis allowing the identification of species of enterococci as well as glycopeptide resistance genes.All the resistant strains were isolated using the enrichment technique. The incidence of GRE (VanA) carriage was 0,55% (two out of 362 patients, two out of 448 isolates) with two Enterococcus faecium VanA. Six Enterococcus gallinarum VanC1 and two Enterococcus casseliflavus VanC2/C3 were also isolated and identified. The main clinics concerned are intensive care and hematology. The two patients with E. faecium VanA had been previously given glycopeptides for 10 days. For three strains, the molecular method allowed to correct prior erroneous results based on rapid identification (RapidID32Strep V2.0).The method using direct samples inoculation underestimates real incidence of GRE carriage. The performances of Génotype(®) Enterococcus molecular method, evaluated for other parameters using reference strains and DNA sequencing, offer new possibilities applicable to routine laboratory.

La résistance aux antibactériens a officiellement commencé le jour de la première administration d une molécule antibiotique, et restera probablement un compagnon de route pour une durée indéterminée (tant que les Hommes et les bactéries "cohabiteront" ?). L'année 2008 marque les 20 ans de la publication du 1er rapport d'isolats cliniques d'ERV (Entérocoques Résistants à la Vancomycine). Depuis ces 1ers cas, les ERV ou ERG (Entérocoques Résistants aux Glycopeptides) ont émergé comme d'importants pathogènes nosocomiaux, stimulant une intense recherche pour élucider à la fois l'épidémiologie, les mécanismes de la résistance et les facteurs de risque responsables de l'apparition et de la dissémination de ces pathogènes, généralement considérés comme peu virulents. L'objet de ce mémoire est d'appréhender une épidémie à ERG du point de vue du bactériologiste. Le développement de méthodes sensibles et spécifiques pour le dépistage des colonisations ou infections à ERG, chez un nombre important de patients, simple et facile à mettre en oeuvre, est indispensable au contrôle de la dissémination de ces pathogènes hautement résistants aux antibiotiques. Les méthodes de PCR temps réel ont fait l'objet d un développement important ces dernières années, en particulier pour le dépistage de BMR telles que les ERG, mais ces techniques sont souvent beaucoup trop coûteuses et complexes pour être mises en oeuvre lors d'une épidémie. Ces techniques n'étaient pas implantées dans notre laboratoire au moment de la résurgence de l'épidémie, et demandaient trop de matériel et de mises au point, pour être installées en urgence. Devant les progrès récents en terme de substrats chromogéniques spécifiques, possédant une sensibilité suffisante pour détecter les ERG au sein d une flore intestinale polymorphe et abondante, nous avons opté pour cette option, tout en gardant la PCR multiplex comme technique de confirmation. Le milieu chromID VRE (bioMérieux) nous a particulièrement séduit, puisque l'incorporation de deux substrats chromogènes, cibles de deux enzymes spécifiques de E. faecalis ([alpha]-glucosidase) et de E. faecium ([bêta]-galactosidase), permet une identification présomptive de ces deux espèces. Au travers des différentes études menées au sein de notre laboratoire, nous avons montré que ce milieu nous permet d'allier sensibilité (avec une lecture après 48 h d'incubation), spécificité (à l'aide de la coloration de Gram, permettant d'éliminer la grande majorité des faux positifs), facilité d'utilisation et de lecture. En association cette méthode classique de culture à la Biologie Moléculaire (PCR multiplex permettant identification et recherche des gènes de résistance, en confirmation), nous avons mis en place un schéma permettant un dépistage efficient des patients porteurs d ERG, dans les meilleurs délais.

Over the two last decades, Enterococcus faecalis has emerged as major cause of nosocomial infections. E. faecalis is also a member of the few bacteria that are almost completely resistant to one of the most important and widespread compounds of the constitutive defence system: the lysozyme. Therefore, the bases of this high resistance to lysozyme were investigated within this thesis work. We identified two genes referred as EF0783 and EF1843, potentially involved in lysozyme resistance. Proteins encoded by these genes share homology with Staphylococcus aureus peptidoglycan O-acetyltransferase (OatA) and Streptococcus pneumoniae Nacetylglucosamine deacetylase (PgdA), respectively. We constructed the corresponding mutants (DEF0783 and DEF1843) and the double mutant DEF0783-DEF1843. We showed that EF0783 mutation leads to the loss of O-acetyl groups from the peptidoglycan and to a decrease of the lysozyme resistance. On the other hand, no effect on lysozyme sensitivity could be associated to the EF1843 gene. Moreover, the EF0783 and/or EF1843 deletions significantly affect the ability of E. faecalis to survive within murine macrophages. While EF0783 is involved in the lysozyme resistance, the peptidoglycan O-acetylation and de-N-acetylation are not the main mechanisms conferring high levels of lysozyme resistance to E. faecalis. Experiments aiming to identify additional factors explaining this lysozyme resistance have to be considered., Lors des deux dernières décennies, Enterococcus faecalis a émergé comme une cause majeure d'infections nosocomiales. E. faecalis est une des rares bactéries presque complètement résistante à l'un des composés les plus importants et les plus répandus du système immunitaire inné : le lysozyme. C'est donc l'étude des causes de cette résistance qui nous a intéressé au cours de ce travail de thèse. Nous avons identifié deux gènes nommés EF0783 et EF1843, potentiellement impliqués dans la résistance au lysozyme. Les protéines codées par ces gènes partagent respectivement des homologies avec une O-acétyltransférase du peptidoglycane (OatA) de Staphylococcus aureus et une N-acétylglucosamine déacétylase (PgdA) de Streptococcus pneumoniae. Nous avons construit les mutants correspondants (DEF0783 et DEF1843) et le double mutant DEF0783-DEF1843. Nous avons montré que la mutation de EF0783 entraînait la perte des groupements O-acétyles du peptidoglycane ainsi qu'une diminution de la résistance au lysozyme. Par contre, aucun effet sur la résistance au lysozyme n'a été associé au gène EF1843. De plus, la délétion de EF0783 et/ou de EF1843 affecte significativement la capacité d'E. faecalis à survivre dans des macrophages murins. Bien que EF0783 soit effectivement impliqué dans la résistance au lysozyme, la Oacétylation et la dé-N-acétylation ne sont pas les principaux mécanismes conférant les hauts niveaux de résistance au lysozyme à E. faecalis. Des expériences pour identifier d'autres facteurs expliquant cette résistance au lysozyme sont à envisager.

We report the case of a 28-year-old intravenous drug abuser under quadritherapy for stage C3 AIDS and with past history of infectious endocarditis. He was admitted with a diminished general condition, weight loss, progressive unbearable abdominal pain and vomiting, without fever. An inflammatory syndrome is noted and imaging reveals a voluminous splenic abscess. Conservative treatment is initiated with repetitive drainages and intravenous antibiotics. Aetiologies, diagnosis and possible therapeutics of splenic abscesses are discussed.

The aim of this study was to evaluate the rate of glycopeptides-resistant enterococci (GRE) fecal carriage (species and resistance determinants). Strains isolated between 1999 and 2005 during systematic screening for multiresistant bacteria in patients hospitalized in 3 intensive care units (ICU) of the University Hospital of Montpellier were studied.The systematic screening was weekly performed. Rectal swabs were cultured on D-Coccosel agar medium containing 4 mg/l vancomycin and MICs for vancomycin and teicoplanin were determined by E-test. Strains were subjected to both phenotypic and genotypic identification and vanA, vanB and vanC genes were detected by PCR.We analyzed 13003 samples for 5113 patients. Among them, 401 (7.84%) patients were GRE carriers with 280 Enterococcus gallinarum (vanC(1)), 102 Enterococcus casseliflavus-flavescens (vanC(2)-C(3)), 5 Enterococcus faecalis (3 vanA, 2 vanB), and 14 Enterococcus faecium (10 vanA, 4 vanB). A unique case of cross contamination between two patients was observed. During the same time, only one strain of GRE was isolated during an infectious process in another unit. Carriage rate of E. faecium and E. faecalis vanA or vanB was 0.37%: 68.4, 21 and 10.6% in the gastrointestinal, in the polyvalent and the respiratory ICU, respectively.Our results were in agreement with national data showing a relatively low GRE fecal carriage rate in ICUs, E. faecium vanA being the mainly encountered GRE. Since 2004, GRE detection is increasingly reported in France and an emerging E. faecium vanA clone has been identified during outbreaks. In contrast, only one E. faecium vanB strain has been isolated in our institution since this date and a unique strain of E. faecalis vanA was isolated during an infectious process since 1999. These data underlined the efficacy of transmission prevention measures established when GRE are identified.

International audience

This work was aimed to analyze trends in susceptibility to antibiotics among the main species of beta-hemolytic streptococci involved in community-acquired infections in human (Streptococcus pyogenes and Streptococcus agalactiae), or in animals (Streptococcus suis and Streptococcus uberis) and also among the main enterocci species, Enterococcus faecalis and Enterococcus faecium. Data were recorded since 1996 through the Onerba networks. S. pyogenes, as the other beta-hemolytic streptococci studied remained fully susceptible to beta-lactam antibiotics. However, susceptibility to macrolides is clearly decreasing in S. pyogenes. In 2002, only 62 to 65% of the strains according to the network considered, were susceptible to erythromycin. A similar trend was observed for S. agalactiae with only 75% of erythromycin susceptibility in 2002, and for both species isolated from animals S. suis and S. uberis, with respectively 35 and 76% of strains susceptible to erythromycin. In enterococci, susceptibility to beta-lactams remained stable between 2000 and 2004. Indeed, the susceptibility to aminopenicillins remained high in E. faecalis (about 98%), whereas the proportion of E. faecium isolates susceptible to these antibiotics were lower than 60%. From 1999 to 2004, various studies conducted in French hospitals showed that the vancomycin resistance among enterococci accounted for less than 2%. However, the recent emergence of glycopeptide resistant enterococci clusters in French hospitals is a matter of concern and emphasizes the need for an ongoing surveillance. Such trend in macrolide resistance among S. pyogenes or S. agalactiae should consequently lead to propose other alternatives in case of beta-lactam allergy, and for pharyngitis, to rethink the place of the culture for susceptibility testing.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The aim of the study was to assess the efficiency of low doses of peracetic acid against viral and bacterial indicators in wastewater and to evaluate if the treatment allows regulatory requirements to be satisfied. A total of 31 samplings were carried out, each involving the collection of secondary effluent and of effluent disinfected with 1.2 or 1.5 mg l(-1) of peracetic acid (contact time 20 minutes). In each sample were measured: somatic coliphages, F-specific RNA bacteriophages, Escherichia coli, total and faecal coliforms, enterococci. Peracetic acid disinfection showed significant differences between the reductions of the microorganisms tested: E. coli showed the highest reduction (1.78 and 2.43 Log respectively with 1.2 and 1.5 mg l(-1) of peracetic acid) and phages the lowest (ranging between 0.52 and 0.60 Log). Only a concentration of 1.5 mg l(-1) of peracetic acid would enable the effluent to be discharged into surface waters in compliance with Italian regulations. The variability of microbial resistance against the peracetic acid disinfection treatment, underlines the importance of assessing disinfection efficiency by using more than one indicator microorganism. The detection of E. coli could be usefully accompanied by tests for more resistant microorganisms such as enterococci or coliphages. In conclusion, peracetic acid can be used for the disinfection of effluents even at low doses, with the advantage of reducing costs and preventing the formation of significant amounts of genotoxic by-products.

National audience

Ce travail rétrospectif est destiné à mesurer l'efficacité de décolonisations par streptomycine orale chez des patients porteurs, au niveau du tractus digestif, d'entérocoques résistants à la vancomycine (ERV) présentant un bas niveau de résistance à la streptomycine.Méthode : administration orale de 1000 mg de streptomycine, 3 fois par jour pendant 10 jours. Ecouvillonage rectal 48 et 96 heures après la fin de la procédure. Evaluation de la rémanence des décolonisations obtenues par écouvillonage rectal hebdomadaire, mensuel ou itératif, selon les services, jusqu'à re-positivation des selles ou jusqu'à ce que le patient soit perdu de vue. Résultat : les tentatives de décolonisation digestives (n=29), ont échoué dans 45 % des cas, et ont été couronnées d'un succès immédiat dans 55 % des cas, dont 62 % restent indemnes d'une recolonisation digestive ultérieure par l'ERV (durée moyenne de suivi: 3 mois). Conclusion : cette méthode a une efficacité à moyen terme inférieure à 35%.

To evaluate a strategy based on screening and isolation at admission to a department of infectious diseases during an epidemic of vancomycin-resistant Enterococcus (VRE) at the University Hospital of Clermont-Ferrand.Systematic screening for VRE by anal swabs began on November 15, 2004. Patients were isolated on admission if (a) they had been hospitalized more than 24 h in an at-risk department of our hospital or (b) they had received a course of wide-spectrum antimicrobial therapy for longer than 48 h in the three months preceding admission. Patients hospitalized in our department were screened weekly if they were treated with wide-spectrum antibiotics, had a urinary catheter left in place for one week, or were neutropenic.Through May 15, 2005, 12 (3.5%) of 341 swabs were found to be positive for VRE: eight were detected on admission and four during hospitalization. In all, 81 patients were isolated on admission. A case-control study confirmed that the criteria for patient isolation were indeed risk factors for VRE. Isolation was well accepted when it was clearly explained. No new case has been detected since March 2005.An isolation strategy based on known risk factors for VRE with systematic screening on admission appears to be an effective way to control an outbreak of VRE, perhaps in part because it helps to keep the medical staff alert to this problem. Isolation is well tolerated as long as it is explained clearly.

Screening for Vancomycin Resistant Enterococci (VRE) is recommended for preventing nosocomial infections with VRE. The aim of this study was to assess the performance of VCA3 agar (bioMérieux) in VRE isolation from fecal specimens. 220 specimens were cultured on VCA3 agar, which contains vancomycin and in parallel, on CAP agar (Oxoid), which is vancomycin-free. 36 vancomycin resistant enterococci were isolated: 24 isolates of Enterococcus faecium expressed a high-level resistance to vancomycin and 12 isolates of E. gallinarum/casseliflavus exhibited resistance at low-level. The sensitivity of VCA3 appeared greater than that of CAP for VRE isolation: 92% (22/24) vs 79% (19/24) for E. faecium (NS, P0.05) ; 83% (10/12) vs 50% (6/12) for E. gallinarum/casselliflavus (NS, P0.05). As expected, initial cultures of multiple gram positive organisms were far more frequent on CAP agar than on VCA3 agar. The isolation rate of vancomycin susceptible gram positive strains was impressively lower on VCA3 medium than on CAP medium. VCA3 agar avoided therefore additional subcultures, useless identification and susceptibility tests. In conclusion, VCA3 medium could be useful for the direct, rapid and selective isolation of VRE from fecal specimens.

The aim of this study was the description of enterococcal bacteremia and the evaluation of their resistance evolution to antibiotics and the virulence profile of these isolates.We have studied all the bacteremia caused by Enterococcus spp. from the 1st of July 2003 until the 30th of June 2004 at Nîmes university hospital. For each isolate, population, clinical and microbiological data were collected. Multiplex PCR allowed for the identification of glycoprotein resistant phenotypes and furthermore, to identify the main virulence genes found in the enterococci.Thirty-three strains were identified from 33 patients (60.6% male) with a median age of 68 years (median: 3-96). The vital prognostic was calculated in 63.6% of the cases (MacCabeor =1); seven patients died during their hospitalization (21.2%). The infections were nosocomial in 60.6% of the cases. No epidemic was observed. The principal comorbidities were cardiovascular and digestive pathologies. In addition, 54.5% of patients had had a surgical intervention. Enterococcus faecalis (87.9%) was the cause of infection in the majority of cases followed by Enterococcus faecium. Most of the infections were monomicrobial (75.8%). E. faecalis was sensitive to amoxicillin and to glycopeptides but was resistant to norfloxacin, erythromycin and pristinamycin. The same observations were made for the E. faecium with the exception of amoxicillin. E. faecalis had the maximum number of virulence genes and E. faecium the least.The enterococcal bacteremia had mainly a nosocomial origin. The isolates came from digestive tract flora but also from catheters. The mortality rate was 21.2%. A developing sensitivity to erythromycin and pristinamycin was observed in comparison to the data of the ONERBA (2002-2003). Only one isolate was resistant to glycopeptide. This was the first European E. faecium containing the vanD allele. This isolate proved fatal to the patient. The dark evolution of enterococcal bacteremia and their frequent nosocomial origin induce to promote studies intended for better knowing the risk factors of such infections.

The spread of multiresistant Staphylococcus and Enterococcus strains required the development of new drugs. Linezolid is the first molecule of a new antibiotic family, oxazolidinones, with an original mechanism of action. In this general review, the authors first present its antibacterial activity, its pharmacokinetic properties, its therapeutic uses in serious Gram-positive infections, pneumonia, skin and soft tissue infections, and also in other indications. They then explain the rules for administration and tolerability.

Bacteria can resist to antibiotics by active exportation mediated by membrane transporters called efflux pumps. These proteins can be specific of a class of antibiotics or responsible for multidrug resistance (MDR). Energy required by efflux pumps can be provided by transmembrane electrochemical gradient of protons (MFS, RND, SMR families) or sodium ions (MATE family) or by ATP hydrolysis (ABC family). Several physiological functions have been described in prokaryotes, such as protection from environmental toxics and regulation of cell homeostasis, which can indirectly contributes to bacterial virulence. In Gram-negative bacteria, efflux transporters usually are organized as multicomponent systems in which the efflux pump located in the inner membrane works in conjunction with a periplasmic fusion protein and an outer membrane factor. The most frequently encountered pumps are of the RND-type such as AcrB in Escherichia coli or MexB in Pseudomonas aeruginosa. In Gram-positive bacteria, efflux is solely mediated by the pump protein, so described with MFS pumps such as NorA or QacA in Staphylococcus aureus and PmrA in Streptococcus pneumoniae. Efflux transporters have also been described in mycobacteria. Although numerous bacterial pumps have been characterized, the clinical consequences of efflux-mediated resistance are mostly unknown because of variable levels of expression and of the lack of specific markers in laboratory practice. Finally, associating pump-specific inhibitors to efflux-sensitive antibiotics might prove an interesting therapeutic perspective. However, inhibitors that are not toxic to eukaryotic cells remain to be identified.

The frequency of digestive colonization of neutropenic patients by Enterococci during the phase of pre-transplant and post-transplant of bone marrow is important indeed as 441 Enterococcus spp strains have been isolated from stool-cultures and other specimens whithin a period of 35 months in 80 patients. A quantitative stool culture was done on appropriate media. Simple bile-esculine agar (BE) and bile esculine-agar additionned with 6 mg/l of vancomycine (BEV) were used for detecting Enterococci. These organisms were taken into account, when then numeration was10(3) UFC/g of fecal sample on BE and in all cases on BEV. Species isolated were essentially Enterococcus faecalis (39.4%), Enterococcus faecium (34.4%) and Enterococcus casseliflavus (17%). These strains were characterized by a high frequency of high-level resistance to gentamicin (40.8%). Resistance to amoxicillin concerns 40% of E. faecium strains. Seventeen multiresistant strains of E. faecium isolated from 7 patients (colonized during a long period and receiving a gut decontamination treatment) were the subject of a phenotypic analysis (biotyping, antibiotyping and determination of MICs to beta-lactam, aminoglycosides and glycopeptides). This analysis showed that these strains are distinguishable, endogenic and specific for each patient, the common multiresistance trait resulted from the selective pressure of decontamination treatment used for our patient.

Over the last years, the emergence of resistance to antibiotics has complicated the management of streptococcal infections. The resistance of streptococci to antibiotics is increasing and seems to be linked to the consumption of antibiotics. Resistances to antibiotics have been noted in all species of streptococci and no family of antibiotics is unaffected by resistances. The incidence of resistance to antibiotics varies from one species to another and according to countries. Presently, even though no Streptococcus pyogenes has shown diminished susceptibility to betalactams, this phenomenon has been reported for some strains in the B, C, and G groups, and for up to 56 % of oral streptococci. As for the resistance to macrolides, it reaches as many as 41 % of Streptococcus pyogenes, 46 % of group B streptococci, and 63 % of oral streptococci responsible for severe infections. This evolution is worrying for all streptococci but particularly for oral streptococci which represent a potential reservoir of virulence genes, notably towards Streptococcus pneumoniae. New families of antibiotics as the ketolides or the oxazolidinones appear to be effective in the treatment of streptococcal infections, but it seems that only a policy of control of the consumption of antibiotics could globally decrease the occurrence of resistance.