102 research outputs found

    Effect of human vicinity on antimicrobial resistance and integrons in animal faecal Escherichia coli”.

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    Objectives: To determine the level of antimicrobial resistance and the occurrence of class 1, 2 and 3 integrons in faecal Escherichia coli from several animal populations variously exposed to human contact. Methods: A collection of 341 faecal E. coli isolates was constituted from several animal populations subject to various degrees of exposure to humans: 18 animals never exposed to humans (living in the Antarctic or Gabon), 71 wild animals living in a low human density area (mountainous region of the Pyrenees, France), 61 wild animals living in a higher human density area (Fontainebleau forest near Paris, France), and 128 extensively reared farm animals and 42 pet dogs, both living in the Pyrenees. Resistance to antimicrobial agents was determined by the method of disc diffusion and quantified using the resistance score of BE Murray, JJ Mathewson, HL DuPont, CD Ericsson and RR Reves (Antimicrobial Agents and Chemotherapy 1990; 34: 515-18). Integrons were characterized by triplex realtime PCR and sequencing. The absence of epidemiologic clones was confirmed by PCR-based methods. Results: A gradient of resistance ranging from absence to high prevalence (resistance score of 18.7%) and a gradual increase in the prevalence of class 1 integrons (from 0% to 16%), both correlated with the increase in exposure to humans, were observed. In wild animals with little contact with humans, resistance, when present, was not mediated by integrons. Conclusions: Our findings firmly establish that the current prevalence of antimicrobial resistance found in animal faecal bacteria, as well as the prevalence of integrons, is clearly anthropogenic. The presence of integrons may constitute an adaptive process to environments whose antimicrobial pressure exceeds a certain threshold

    Fungal microbiota dysbiosis in IBD.

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    International audienceThe bacterial intestinal microbiota plays major roles in human physiology and IBDs. Although some data suggest a role of the fungal microbiota in IBD pathogenesis, the available data are scarce. The aim of our study was to characterise the faecal fungal microbiota in patients with IBD. Bacterial and fungal composition of the faecal microbiota of 235 patients with IBD and 38 healthy subjects (HS) was determined using 16S and ITS2 sequencing, respectively. The obtained sequences were analysed using the Qiime pipeline to assess composition and diversity. Bacterial and fungal taxa associated with clinical parameters were identified using multivariate association with linear models. Correlation between bacterial and fungal microbiota was investigated using Spearman's test and distance correlation. We observed that fungal microbiota is skewed in IBD, with an increased Basidiomycota/Ascomycota ratio, a decreased proportion of Saccharomyces cerevisiae and an increased proportion of Candida albicans compared with HS. We also identified disease-specific alterations in diversity, indicating that a Crohn's disease-specific gut environment may favour fungi at the expense of bacteria. The concomitant analysis of bacterial and fungal microbiota showed a dense and homogenous correlation network in HS but a dramatically unbalanced network in IBD, suggesting the existence of disease-specific inter-kingdom alterations. Besides bacterial dysbiosis, our study identifies a distinct fungal microbiota dysbiosis in IBD characterised by alterations in biodiversity and composition. Moreover, we unravel here disease-specific inter-kingdom network alterations in IBD, suggesting that, beyond bacteria, fungi might also play a role in IBD pathogenesis

    A transcription factor contributes to pathogenesis and virulence in streptococcus pneumoniae

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    To date, the role of transcription factors (TFs) in the progression of disease for many pathogens is yet to be studied in detail. This is probably due to transient, and generally low expression levels of TFs, which are the central components controlling the expression of many genes during the course of infection. However, a small change in the expression or specificity of a TF can radically alter gene expression. In this study, we combined a number of quality-based selection strategies including structural prediction of modulated genes, gene ontology and network analysis, to predict the regulatory mechanisms underlying pathogenesis of Streptococcus pneumoniae (the pneumococcus). We have identified two TFs (SP_0676 and SP_0927 [SmrC]) that might control tissue-specific gene expression during pneumococcal translocation from the nasopharynx to lungs, to blood and then to brain of mice. Targeted mutagenesis and mouse models of infection confirmed the role of SP_0927 in pathogenesis and virulence, and suggests that SP_0676 might be essential to pneumococcal viability. These findings provide fundamental new insights into virulence gene expression and regulation during pathogenesis.Layla K. Mahdi, Esmaeil Ebrahimie, David L. Adelson, James C. Paton, Abiodun D. Ogunniy

    Evidence for large-scale gene-by-smoking interaction effects on pulmonary function

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    Background: Smoking is the strongest environmental risk factor for reduced pulmonary function. The genetic component of various pulmonary traits has also been demonstrated, and at least 26 loci have been reproducibly associated with either FEV1 (forced expiratory volume in 1 second) or FEV1/FVC (FEV1/forced vital capacity). Although the main effects of smoking and genetic loci are well established, the question of potential gene-by-smoking interaction effect remains unanswered. The aim of the present study was to assess, using a genetic risk score approach, whether the effect of these 26 loci on pulmonary function is influenced by smoking. Methods: We evaluated the interaction between smoking exposure, considered as either ever vs never or pack-years, and a 26-single nucleotide polymorphisms (SNPs) genetic risk score in relation to FEV1 or FEV1/FVC in 50 047 participants of European ancestry from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) and SpiroMeta consortia. Results: We identified an interaction (beta(int) = -0.036, 95% confidence interval, -0.040 to -0.032, P = 0.00057) between an unweighted 26 SNP genetic risk score and smoking status (ever/never) on the FEV1/FVC ratio. In interpreting this interaction, we showed that the genetic risk of falling below the FEV1/FVC threshold used to diagnose chronic obstructive pulmonary disease is higher among ever smokers than among never smokers. A replication analysis in two independent datasets, although not statistically significant, showed a similar trend in the interaction effect. Conclusions: This study highlights the benefit of using genetic risk scores for identifying interactions missed when studying individual SNPs and shows, for the first time, that persons with the highest genetic risk for low FEV1/FVC may be more susceptible to the deleterious effects of smoking.Peer reviewe

    Adaptation aux variations d'environnement des souches commensales d'escherichia coli

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    E. coli est l'entérobactérie principale de la flore commensale intestinale. Elle est également une des principales causes d'inffection bactérienne chez l'homme. Au cours de notre travail de thèse nous avons étudié l'adaptation de cette espèce à la pression de sélection antibiotique, vers la résistance, actuellement un problème majeur de santé publique. pour cela, nous avons analysé les variations de diverses caractéristiques (phénotype de résistance aux antibiotiques et au meercure, intégrons, diversité, répartition phylogénétiques, association à la virulence) liées à la résistance chez des échantillons de souches intestinales humaines et animales, recueillies dans des environnements spécifiques et contrastés.We studied variations of characteristics of human and animal commensal E. coli to variations of their hosts environment. Prevalence of antibiotic resisance, of integron, of mercury resistance, phylogenetic repartition and intra-host diversity were selected; More animals were ling near humans, more their commensal E. coli were resistant and more the prevalence of integron was high, while the intra-host diversity decreased. in human commensal E. coli, characteristics of isolates from expatriates living in French Guyana, were found intermediate between those found in isolates from residents in metropolitan france and those found in natives living permanently in french guyana, probably the result from their living in an environment close to that of the native Guyaneses but with a way of life close to that of residents living in metropolitan france. in conclusion our results suggest that the environment strongly influence the composition of the commensal intestinal flora of humans and animals.PARIS5-BU Méd.Cochin (751142101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF
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