24 research outputs found

    Difference in virulence between Staphylococcus aureus isolates causing gangrenous mastitis versus subclinical mastitis in a dairy sheep flock

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    Staphylococcus aureus mastitis in dairy sheep ranges from subclinical mastitis to lethal gangrenous mastitis. Neither the S. aureus virulence factors nor the host-factors or the epidemiological events contributing to the different outcomes are known. In a field study in a dairy sheep farm over 21 months, 16 natural isolates of S. aureus were collected from six subclinical mastitis cases, one lethal gangrenous mastitis case, nasal carriage from eight ewes and one isolate from ambient air in the milking room. A genomic comparison of two strains, one responsible for subclinical mastitis and one for lethal gangrenous mastitis, was performed using multi-strain DNA microarrays. Multiple typing techniques (pulsed-field-gel-electrophoresis, multiple-locus variable-number, single-nucleotide polymorphisms, randomly amplified polymorphic DNA, spa typing and sas typing) were used to characterise the remaining isolates and to follow the persistence of the gangrenous isolate in ewes’ nares. Our results showed that the two strains were genetically closely related and they shared 3 615 identical predicted open reading frames. However, the gangrenous mastitis isolate carried variant versions of several genes (sdrD, clfA-B, sasA, sasB, sasD, sasI and splE) and was missing fibrinogen binding protein B (fnbB) and a prophage. The typing results showed that this gangrenous strain emerged after the initial subclinical mastitis screening, but then persisted in the flock in the nares of four ewes. Although we cannot dismiss the role of host susceptibility in the clinical events in this flock, our data support the hypothesis that S. aureus populations had evolved in the sheep flock and that S. aureus genetic variations could have contributed to enhanced virulence

    Home and Online Management and Evaluation of Blood Pressure (HOME BP) using a digital intervention in poorly controlled hypertension: randomised controlled trial

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    Objective: The HOME BP (Home and Online Management and Evaluation of Blood Pressure) trial aimed to test a digital intervention for hypertension management in primary care by combining self-monitoring of blood pressure with guided self-management. Design: Unmasked randomised controlled trial with automated ascertainment of primary endpoint. Setting: 76 general practices in the United Kingdom. Participants: 622 people with treated but poorly controlled hypertension (>140/90 mm Hg) and access to the internet. Interventions: Participants were randomised by using a minimisation algorithm to self-monitoring of blood pressure with a digital intervention (305 participants) or usual care (routine hypertension care, with appointments and drug changes made at the discretion of the general practitioner; 317 participants). The digital intervention provided feedback of blood pressure results to patients and professionals with optional lifestyle advice and motivational support. Target blood pressure for hypertension, diabetes, and people aged 80 or older followed UK national guidelines. Main outcome measures: The primary outcome was the difference in systolic blood pressure (mean of second and third readings) after one year, adjusted for baseline blood pressure, blood pressure target, age, and practice, with multiple imputation for missing values. Results: After one year, data were available from 552 participants (88.6%) with imputation for the remaining 70 participants (11.4%). Mean blood pressure dropped from 151.7/86.4 to 138.4/80.2 mm Hg in the intervention group and from 151.6/85.3 to 141.8/79.8 mm Hg in the usual care group, giving a mean difference in systolic blood pressure of −3.4 mm Hg (95% confidence interval −6.1 to −0.8 mm Hg) and a mean difference in diastolic blood pressure of −0.5 mm Hg (−1.9 to 0.9 mm Hg). Results were comparable in the complete case analysis and adverse effects were similar between groups. Within trial costs showed an incremental cost effectiveness ratio of £11 ($15, €12; 95% confidence interval £6 to £29) per mm Hg reduction. Conclusions: The HOME BP digital intervention for the management of hypertension by using self-monitored blood pressure led to better control of systolic blood pressure after one year than usual care, with low incremental costs. Implementation in primary care will require integration into clinical workflows and consideration of people who are digitally excluded. Trial registration: ISRCTN13790648

    Staphylococcus aureus et mammites (identification de facteurs staphylococciques impliqués dans la sévérité des mammites ovines)

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    Staphylococcus aureus est un des agents majeurs impliquĂ©s dans les mammites chez les ruminants. Les mammites staphylococciques ovines ont la particularitĂ© de prĂ©senter des degrĂ©s de sĂ©vĂ©ritĂ© trĂšs variables, allant des mammites subcliniques aux mammites gangrĂ©neuses mais les facteurs relatifs Ă  S. aureus permettant d expliquer cette variabilitĂ© de symptĂŽmes sont pour le moment mĂ©connus. Cette Ă©tude vise Ă  identifier les facteurs staphylococciques impliquĂ©s dans la sĂ©vĂ©ritĂ© des mammites. Deux souches de S. aureus isolĂ©es de mammite ovine gangrĂ©neuse (O11) ou subclinique (O46) ont Ă©tĂ© sĂ©lectionnĂ©es pour l Ă©tude. Ces deux souches, bien que gĂ©nĂ©tiquement proches induisent des symptĂŽmes distincts lors d infections expĂ©rimentales (modĂšle brebis et souris). La combinaison de plusieurs approches pour comparer O11 et O46 a permis la mise en Ă©vidence de quelques pistes expliquant l origine de ces diffĂ©rences. Le sĂ©quençage des souches et leurs analyses transcriptomiques et protĂ©omiques en conditions mimant le contexte mammite rĂ©vĂšlent ainsi que les diffĂ©rences majeures entre O11 et O46 rĂ©sident plus dans leur capacitĂ© Ă  s adapter et Ă  exprimer des facteurs de virulence dans le contexte mamelle que dans leur contenu en gĂšnes. De façon marquante, cette Ă©tude a montrĂ© des diffĂ©rences entre O11 et O46 dans l expression des Ă©lĂ©ments gĂ©nĂ©tiques mobiles, l expression des gĂšnes impliquĂ©s dans l acquisition et le mĂ©tabolisme du fer, l expression des facteurs SigmaB et SigmaS et la production d exoprotĂ©ines. L utilisation de l approche Serological Proteome Analysis (SERPA) nous a permis de montrer que la plupart de ces exoprotĂ©ines est produite au cours de la mammite. Parmi ces protĂ©ines, nous avons pu confirmer la production pour au moins deux d entre elles, SspB et une protĂ©ine de fonction inconnue, dans 10 autres souches de S. aureus, isolĂ©es de mammites sĂ©vĂšres (sspB) ou de mammites subcliniques (protĂ©ine de fonction inconnue). Le rĂŽle des protĂ©ines identifiĂ©es, des Ă©lĂ©ments gĂ©nĂ©tiques mobiles ou des facteurs impliquĂ©s dans le mĂ©tabolisme martial, dans la mammite et dans la sĂ©vĂ©ritĂ© de la mammite restent Ă  dĂ©terminer. Ces travaux ont ainsi permis l identification de plusieurs gĂšnes potentiellement impliquĂ©s dans le processus infectieux et la sĂ©vĂ©ritĂ© des mammites. Bien que la rĂ©elle implication de ces gĂšnes (et fonction) reste Ă  dĂ©montrer, ces rĂ©sultats ouvrent la voie Ă  des Ă©tudes plus approfondies sur certaines fonctions qui pourront ĂȘtre la cible de stratĂ©gies de prĂ©vention ou de traitement des mammites staphylococciques.Staphylococcus aureus is one of the main pathogen involved in ruminant mastitis. Severity of ovine S. aureus mastitis is highly variable, ranging from subclinical to gangrenous mastitis. Nevertheless S. aureus factors that may explain this variability have been neglected until now. The aim of this study is to identify S. aureus factors that are involved in severity of mastitis. Two S. aureus strains isolated from a gangrenous (O11) or a subclinical mastitis (O46) have been selected for this study. Despite being closely related, both strains induced dramatically different symptoms when used in experimental mastitis infections (in ruminant and mice model). Combination of several approaches highlighted some pathways than could explain observed differences between O11 and O46 strains. Gene sequencing of both strains and their transcriptomic and proteomic analyses in conditions mimicking mastitis revealed thus that the major differences between O11 and O46 lied more in their ability to adapt and express virulence factors in the mammary gland context rather than in their gene content. This study showed differences between O11 and O46 in the expression of mobile genetic elements, of genes implied in iron acquisition and metabolism, of SigmaB and SigmaS factors and in exoprotein production. Serological proteome Analysis (SERPA) showed that most of these exoproteins were produced during mastitis. Among these proteins, we confirmed the production of at least two of them, SspB and a hypothetical protein in 10 other S. aureus isolated from severe mastitis (SspB) or subclinical mastitis (hypothetical protein). The role of identified proteins, mobile genetic elements or factors implied in iron metabolism during mastitis or in mastitis severity remains to be determined. This work allowed the identification of several genes potentially involved in infectious process and severity of mastitis. Although the role of identified factors has still to be further determined, the current study opens avenues for a better understanding of S. aureus pathogenesis during mastitis and for potential clinical applications.RENNES-Agrocampus-CRD (352382323) / SudocSudocFranceF

    Exploration of the Diversity of Clustered Regularly Interspaced Short Palindromic Repeats-Cas Systems in Clostridium novyi sensu lato

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    International audienceClassified as the genospecies Clostridium novyi sensu lato and distributed into four lineages (I–IV), Clostridium botulinum (group III), Clostridium novyi , and Clostridium haemolyticum are clostridial pathogens that cause animal diseases. Clostridium novyi sensu lato contains a large mobilome consisting of plasmids and circular bacteriophages. Here, we explored clustered regularly interspaced short palindromic repeats (CRISPR) arrays and their associated proteins (Cas) to shed light on the link between evolution of CRISPR-Cas systems and the plasmid and phage composition in a study of 58 Clostridium novyi sensu lato genomes. In 55 of these genomes, types I-B (complete or partial), I-D, II-C, III-B, III-D, or V-U CRISPR-Cas systems were detected in chromosomes as well as in mobile genetic elements (MGEs). Type I-B predominated (67.2%) and was the only CRISPR type detected in the Ia, III, and IV genomic lineages. Putative type V-U CRISPR Cas14a genes were detected in two different cases: next to partial type-IB CRISPR loci on the phage encoding the botulinum neurotoxin (BoNT) in lineage Ia and in 12 lineage II genomes, as part of a putative integrative element related to a phage-inducible chromosomal island (PICI). In the putative PICI, Cas14a was associated with CRISPR arrays and restriction modification (RM) systems as part of an accessory locus. This is the first time a PICI containing such locus has been detected in C. botulinum . Mobilome composition and dynamics were also investigated based on the contents of the CRISPR arrays and the study of spacers. A large proportion of identified protospacers (20.2%) originated from Clostridium novyi sensu lato (p1_Cst, p4_BKT015925, p6_Cst, CWou-2020a, p1_BKT015925, and p2_BKT015925), confirming active exchanges within this genospecies and the key importance of specific MGEs in Clostridium novyi sensu lato

    Development of An Innovative and Quick Method for the Isolation of Clostridium botulinum Strains Involved in Avian Botulism Outbreaks

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    International audienceAvian botulism is a serious neuroparalytic disease mainly caused by a type C/D botulinum neurotoxin produced by Clostridium botulinum group III, one of the entwined bacterial species from the Clostridium novyi sensu lato genospecies. Its isolation is very challenging due to the absence of selective media and the instability of the phage carrying the gene encoding for the neurotoxin. The present study describes the development of an original method for isolating C. botulinum group III strains. Briefly, this method consists of streaking the InstaGene matrix extraction pellet on Egg Yolk Agar plates and then collecting the colonies with lipase and lecithinase activities. Using this approach, it was possible to isolate 21 C. novyi sensu lato strains from 22 enrichment broths of avian livers, including 14 toxic strains. This method was successfully used to re-isolate type C, D, C/D, and D/C strains from liver samples spiked with five spores per gram. This method is cheap, user-friendly, and reliable. It can be used to quickly isolate toxic strains involved in avian botulism with a 64% success rate and C. novyi sensu lato with a 95% rate. This opens up new perspectives for C. botulinum genomic research, which will shed light on the epidemiology of avian botulism

    Kinetic study of thermal inactivation of enterococci and clostridial spores

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    In order to better understand the fate of clostridia and enterococci during the heat treatment of livestock effluents, a first approach consisted in modelling their persistence under specific conditions (culture media, pure strain). The objective of this study is to establish the thermal inactivation kinetics of strains belonging to two species of enterococci (E. faecalis and E. faecium), to the species C. difficile and to the species C. novyi (used as a non-toxic model of C. botulinum group III), by evaluating in particular the scales imposed by European regulations

    <em>Staphylococcus aureus</em>-induced cytopathic effect on the mammalian cells

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    International audienceAttention to the bacterial pathogenesis has increased in the past decade because of antibiotic resistance and recurrence of the old diseases. The precise knowledge of the mechanisms of bacteria-host interactions will help to develop the new effective therapeutics. Staphylococcus aureus is a major cause of a multitude of diseases including severe nosocomial and skin infections, as well as infectious mastitis in mammalian. It produces various virulence factors that induce the host cellular damage during infection. The aim of the study focus on the in vitro analysis of S. aureus cytopathic effects on the human and bovine epithelial cell

    Évaluation des risques en appui des mesures de gestion de produits dans la filiùre bovine, lors de suspicion et de confirmation de cas de botulisme: Avis de l’Anses. Rapport d’expertise collective

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    Anses. (2021). Évaluation des risques en appui des mesures de gestion de produits dans la filiĂšre bovine, lors de suspicion et de confirmation de cas de botulisme (saisine 2019-SA-0112): Avis de l'Anses. Rapport d'expertise collective. Maisons-Alfort : Anses, 112 pLe botulisme est une maladie neurologique humaine et animale provoquĂ©e par l’action de neurotoxines bactĂ©riennes (toxines botuliques) produites par des bactĂ©ries du genre Clostridium et qui se manifeste par des paralysies flasques pouvant aller jusqu’à la paralysie respiratoire et l’arrĂȘt cardiaque. Il existe neuf types connus de toxines botuliques.Le botulisme animal en France concerne essentiellement les oiseaux (sauvages et domestiques) et les bovins. Les cas chez les bovins sont dus aux types mosaĂŻque D/C (majoritaire), C, C/D et rarement au D. Au niveau national, l’incidence observĂ©e les 10 derniĂšres annĂ©es est en moyenne d’une dizaine de foyers par an. Bien qu’il s’agisse d’une maladie animale de premiĂšre catĂ©gorie, il n’y a pas Ă  l’heure actuelle de mesures de police sanitaire Ă©tablies par la rĂ©glementation, lors de la confirmation d’un foyer de botulisme animal, ce qui conduit Ă  une gestion au cas par cas par les directions dĂ©partementales de la protection des populations (DDPP) et la mission des urgences sanitaires (MUS) de la DGAL. Cesservices peuvent s’appuyer sur deux documents Ă©mis par l’Afssa : le rapport sur le botulisme animal Ă©tabli en 2002 et l’avis rendu en janvier 2009 sur un projet d’arrĂȘtĂ© fixant des mesures techniques et administratives relatives Ă  la lutte contre le botulisme aviaire. Les rapports et avis citĂ©s Ă©tant relativement anciens, la DGAL a saisi l’Anses via 4 saisines (saisines 2019-SA-0112 Ă  2019-SA-0115), dont l’objet est une demande d’actualisation des connaissances et des Ă©valuations de risque pour la santĂ© humaine et/ou animale.L’expertise a Ă©tĂ© rĂ©alisĂ©e en deux Ă©tapes :1. Une mise Ă  jour des connaissances sur Clostridium botulinum (types C, D, mosaĂŻques C/D et D/C et E) effectuĂ©e par le groupe de travail (GT) « Groupe socle botulisme », portant sur les caractĂ©ristiques microbiologiques, les maladies humaine et animale (bovins, oiseaux et poissons), la prĂ©sence des diffĂ©rentes formes et types dans l’environnement, le danger dans les denrĂ©es alimentaires d’origine animale ainsi que l’efficacitĂ© des mĂ©thodes et procĂ©dĂ©s d’inactivation.2. Le traitement des questions d’évaluation des risques par des groupes de travail spĂ©cifiques (« Botulisme bovin-aviaire » ; « DĂ©contamination » ; « Faune sauvage et environnement »).La prĂ©sente saisine porte sur l’évaluation des risques en appui des mesures de gestion de produits dans la filiĂšre bovine, lors de suspicion et de confirmation de cas de botulisme dans un troupeau. Les questions posĂ©es dans la saisine sont les suivantes :- « Quel est le risque pour l’Homme liĂ© Ă  la consommation de produits carnĂ©s ou laitiers provenant d’un bovin en incubation ou atteint de botulisme ? Le risque est-il diffĂ©rent selon les souches bactĂ©riennes et la population concernĂ©e (nourrissons, enfants, adultes, personnes fragiles) ?Comment l’état de santĂ© des animaux influence-t-il le risque pour le consommateur final (importance relative entre la phase d’incubation et la phase clinique) ?- Quel est le risque potentiel associĂ© aux produits carnĂ©s et laitiers issus des autres animaux du troupeau que ceux strictement malades ? Existe-t-il des moyens pour diminuer ce risque de contamination des produits ?- La manipulation de carcasses en abattoir d’un animal issu d’un lot de bovins atteints de botulisme mais dĂ©pourvus de signes cliniques prĂ©sente-t-elle un risque pour les employĂ©s de contracter le botulisme ? Comment le maĂźtriser ?- Quelle est l’efficacitĂ© des diffĂ©rents traitements du lait sur les formes vĂ©gĂ©tatives et sporulĂ©es (pasteurisation, traitement UHT, bactofugation, filtration membranaire) ? Dans quelle mesure peuvent-ils ĂȘtre considĂ©rĂ©s comme assainissant

    La méthanisation agricole en France : contribution à la transition agroécologique ou opportunité énergétique ?

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    Suite Ă  un workshop organisĂ© en octobre 20222 Ă  Rennes sur la mĂ©thanisation et l’agroĂ©cologie, cet article prĂ©sente une synthĂšse des principaux rĂ©sultats et questionnements discutĂ©s lors de cet Ă©vĂšnement et propose des perspectives pour une mĂ©thanisation agroĂ©cologique.Anaerobic digestion in France: contribution to the agro-ecological transition or energy opportunity?Following a workshop organized in October 20222 in Rennes on anaerobic digestion and agroecology, this article presents a synthesis of the main results and questions discussed during this event and proposes perspectives for agroecological anaerobic digestion
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