29 research outputs found
Distribution and characterization of integrons in Escherichia colistrains of animal and human origin
No full textOne hundred and twenty clinical and commensal Escherichia coli strains isolated in Switzerland from humans and from companion and farm animals were analysed for the prevalence of integrons of classes 1, 2, and 3 and for the characterization of their gene cassettes. The relationships between integron carriage and host category, and between integron carriage and phylogenetic E. coli lineage were also analysed. Integrons were detected in 48 (40%) of the isolates and were thus widely disseminated in the human and animal E. coli strains considered. Moreover, the association between integron carriage and certain animal categories (farm animals) suggests that animals that are raised for economic purposes might be exposed to a major antibiotic pressure. Finally, our data confirm that E. coli commensal strains represent a significant source of antibiotic-resistant determinant
Presence of potentially pathogenic Babesia sp. for human in Ixodes ricinus in Switzerland
No full textWe have designed and performed a new PCR method based on the 18S rRNA in order to individuate the presence and the identity of Babesia parasites. Out of 1159 Ixodes ricinus (Acari: Ixodidae) ticks collected in four areas of Switzerland, nine were found to contain Babesia DNA. Sequencing of the short amplicon obtained (411-452 bp) allowed the identification of three human pathogenic species: Babesia microti, B. divergens, for the first time in Switzerland, Babesia sp. EU1. We also report coinfections with B. sp. EU1-Borrelia burgdorferi sensu stricto and Babesia sp. EU1-B. afzelii
Evidence of horizontal gene transfer between human and animal commensal Escherichia coli strains identified by microarray
No full textBacteria exchange genetic material by horizontal gene transfer (HGT). To evaluate the impact of HGT on Escherichia coli genome plasticity, 19 commensal strains collected from the intestinal floras of humans and animals were analyzed by microarrays. Strains were hybridized against an oligoarray containing 2700 E. coli K12 chromosomal genes. A core (genes shared among compared genomes) and a flexible gene pool (genes unique for each genome) have been identified. Analysis of hybridization signals evidenced 1015 divergent genes among the 19 strains and each strain showed a specific genomic variability pattern. Four hundred and fifty-eight genes were characterized by higher rates of interstrain variation and were considered hyperdivergent. These genes are not randomly distributed onto the chromosome but are clustered in precise regions. Hyperdivergent genes belong to the flexible gene pool and show a specific GC content, differing from that of the chromosome, indicating acquisition by HGT. Among these genes, those involved in defense mechanisms and cell motility as well as intracellular trafficking and secretion were far more represented than others. The observed genome plasticity contributes to the maintenance of genetic diversity and may therefore be a source of evolutionary adaptation and survival
Attività dell'Istituto cantonale batteriosierologico (IBS)
No full textL'activité de l'IBS à Lugano se déroule en 4 secteurs principaux: le diagnostic microbiologique, l'expertise, l'enseignement et la recherche. L'IBS traite par année environ 50'000 échantillons cliniques provenant d'hôpitaux, de cliniques et de cabinets médicaux, et sur lesquels sont réalisées des analyses de bactériologie, de mycologie, de parasitologie et de sérologie. Ainsi l'IBS est dans une situation privilégiée pour contribuer à la surveillance épidémiologique des maladies transmissibles chez l'homme. De plus, l'Institut est reconnu par l'OFSP comme laboratoire de confirmation pour le SIDA pour la Suisse italienne. L'activité d'expertise est exercée en faveur des secteurs privé et public. On peut par exemple mentionner la détermination de l'activité antibactérienne de nouvelles molécules mises au point par l'industrie pharmaceutique, ou les analyses bactériologiques de l'eau du Lac de Lugano, effectuées pour la Commission internationale pour la protection des eaux italo-suisses. En plus de l'activité d'enseignement exercée par le directeur et le directeur-adjoint à l'Université de Genève, l'IBS organise ou participe à des cours post-gradués pour les étudiants de l'Université de Genève, aussi en collaboration avec l'EPFL, le Polytechnique de Milan et l'Institut d'hydrobiologie de Pallanza (Italie). Par ailleurs, des étudiants en sciences, en médecine humaine et vétérinaire accomplissent régulièrement leurs travaux de diplôme ou de doctorat à l'Institut. Enfin, l'IBS organise les travaux pratiques pour l'Ecole cantonale de laborants médicaux, ainsi que des cours de formation continue pour les enseignants en sciences du Canton. En outre, la gestion et la coordination du Centre de biologie alpine de Piora est confiée à l'Institut. Concernant la recherche, deux voies principales sont developpées à l'Institut: l'écologie microbienne et la génétique des populations bactériennes. Les recherches réalisées en écologie microbienne (Aeromonas, Legionella, Yersinia) ont abouti notamment à la création, auprès de l'Institut en 1990, du "Laboratoire d'écologie microbienne" de l'Université de Genève. Les recherches réalisées dans le domaine de la génétique des populations (Shigella, Campylobacter. Listeria, Borrelia) en collaboration avec des instituts suisses et étrangers ont aboutis à de nombreuses publications dans des revues internationales
Formulation and characterisation of synthetic glycolipids-loaded liposomes to target Helicobacter pylori
No full textCe travail traite de la formulation et de la caractérisation de liposomes porteurs de glycolipides synthétiques, en vue du ciblage d une bactérie : Helicobacter pylori. Après avoir passé en revue les différents systèmes à temps de résidence gastrique prolongé, il décrit la synthèse et l utilisation de néoglycolipides de type "ancre-espaceur-sucre ", constitué respectivement du cholestérol, du tétra-éthylène glycol et enfin du fucose (ou N-acétylglucosamine). Ont été étudiées dans ce travail l organisation supramoléculaire des néoglycolipides seuls en fonction de leur état d hydratation, les altérations de la bicouche liposomale suite à l incorporation du néoglycolipide, l accessibilité des sucres à la surface des liposomes, la variation du pH intraliposomal en fonction de pH externes acides, et enfin, l interaction de quatre formulations de liposomes contenant ou non les néoglycolipides avec 2 souches d H. pyloriThis thesis is about the formulation and characterisation of synthetic glycolipids-loaded liposomes in order to target a bacterium: Helicobacter pylori. Gastroretentive systems are first reviewed. Secondly, the synthesis and use of the system anchor-spacer-sugar , i.e. cholesterol, tetraethylene glycol and fucose (or N-acetylglucosamine) respectively, are described. During this work, we studied the neoglycolipids supramolecular organization in function of their hydration rate, the alteration of the liposomale bilayer following the neoglycolipid incorporation, the accessibility of the sugar moieties at the liposomes surface, the intraliposomal pH variation in function of acidic external pH, and finally, the interaction between four liposomal formulations bearing or not neoglycolipids with two strains of H. pyloriLYON1-BU.Sciences (692662101) / SudocSudocFranceF
Diversity of the population of Tick-borne encephalitis virus infecting Ixodes ricinus ticks in an endemic area of central Switzerland (Canton Bern)
No full textTick-borne encephalitis virus (TBEV), a member of the genus Flavivirus, has a positive-strand RNA genome containing a single open reading frame flanked by non-coding regions (NCRs). Ixodes ricinus ticks (n = 307) were collected from vegetation in a natural TBEV focus in Belp, Switzerland. The presence and identity of the virus were determined by nested RT-PCR followed by sequencing of the 5'-terminal region that comprises the 5' NCR and the capsid-encoding region (C). The presence of the western European TBEV subtype (W-TBEV) genome was detected in 14.3% of the ticks. Nucleotide sequence analysis revealed a high variability of 55.5%. In particular, four DNA fragments (CS 'A', CS 'B', the folding-stem structure and the start codon) showed substantial heterogeneity, which has the potential of compromising replication, translation and packaging of the viral genome. This variability may reflect a viral strategy to select the fittest RNA molecule to produce a viral infection in the different vertebrate hosts that may be encountered by the ticks. It may also indicate a possible ancient introduction of TBEV to the Belp site. In addition, it may contribute to explaining the annual low incidence of tick-borne encephalitis in the natural focus of Belp, despite the high prevalence of TBEV genomes in ticks
Hepatitis C virus and GBV-C virus prevalence among patients with B-cell lymphoma in different European regions: a case-control study of the International Extranodal Lymphoma Study Group
No full textHepatitis C virus (HCV) infection is associated with some B-cell non-Hodgkin lymphoma (B cell-NHLs). Patients with HCV infection frequently show co-infections with GB virus C (GBV-C, formerly known as hepatitis G virus), and some studies have suggested a higher incidence of GBV-C infection in patients with B cell-NHLs. The aim of this study was to prospectively evaluate the association between HCV and/or GBV-C infection and B cell-NHLs in different geographic areas. One hundred thirty-seven lymphoma cases and 125 non-lymphoma matched controls were enrolled in an international case-control study conducted in Switzerland (Bellinzona), Spain (Barcelona) and England (Southampton) on samples collected from 2001 to 2002. In Bellinzona (41 cases and 81 controls), the overall prevalence of HCV was 3.3% (4.9% in NHLs), and the overall prevalence of GBV-C was 24% (22% in NHLs). In Barcelona (46 cases and 44 controls), the prevalence of HCV was 10% (8.7% in NHLs) and the prevalence of GBV-C 20% (13% in NHLs). There was no statistically significant difference in the frequency of both infections between patients with NHL and controls. In Southampton, 50 NHL cases were analysed, none of them was found to be HCV-positive; therefore, no control group was analysed and GBV-C analysis was not performed, too. Both in Bellinzona and in Barcelona, the seropositivity rate was significantly lower for HCV than for GBV-C, suggesting that their transmission can be independent. The incidence of HCV was significantly higher in Barcelona than that in Bellinzona. This study confirmed the existence of marked geographic differences in the prevalence of HCV in NHL but cannot provide any significant evidence for an association between HCV and/or GBV-C and B-cell NHLs
The European centre for infectious diseases: An adequate response to the challenges of bioterrorism and major natural infectious threats
No full textSCOPUS: ed.jinfo:eu-repo/semantics/publishe
HIV-1 coreceptor usage and CXCR4-specific viral load predict clinical disease progression during combination antiretroviral therapy
No full textBACKGROUND: Although combination antiretroviral therapy (cART) dramatically reduces rates of AIDS and death, a minority of patients experience clinical disease progression during treatment. OBJECTIVE: To investigate whether detection of CXCR4(X4)-specific strains or quantification of X4-specific HIV-1 load predict clinical outcome. METHODS: From the Swiss HIV Cohort Study, 96 participants who initiated cART yet subsequently progressed to AIDS or death were compared with 84 contemporaneous, treated nonprogressors. A sensitive heteroduplex tracking assay was developed to quantify plasma X4 and CCR5 variants and resolve HIV-1 load into coreceptor-specific components. Measurements were analyzed as cofactors of progression in multivariable Cox models adjusted for concurrent CD4 cell count and total viral load, applying inverse probability weights to adjust for sampling bias. RESULTS: Patients with X4 variants at baseline displayed reduced CD4 cell responses compared with those without X4 strains (40 versus 82 cells/microl; P = 0.012). The adjusted multivariable hazard ratio (HR) for clinical progression was 4.8 [95% confidence interval (CI) 2.3-10.0] for those demonstrating X4 strains at baseline. The X4-specific HIV-1 load was a similarly independent predictor, with HR values of 3.7 (95% CI, 1.2-11.3) and 5.9 (95% CI, 2.2-15.0) for baseline loads of 2.2-4.3 and > 4.3 log10 copies/ml, respectively, compared with < 2.2 log10 copies/ml. CONCLUSIONS: HIV-1 coreceptor usage and X4-specific viral loads strongly predicted disease progression during cART, independent of and in addition to CD4 cell count or total viral load. Detection and quantification of X4 strains promise to be clinically useful biomarkers to guide patient management and study HIV-1 pathogenesis
