421 research outputs found
Multidrug-Resistant Bacteria in the Community
Multidrug resistant (MDR) bacteria are one of the most important current threats to public health. Typically, MDR bacteria are associated with nosocomial infections. However, some MDR bacteria have become quite prevalent causes of community-acquired infections. The spread of MDR bacteria into the community is a crucial development, and is associated with increased morbidity, mortality, healthcare costs and antibiotic use. Factors associated with community dissemination of MDR bacteria overlap but are distinct from those associated with nosocomial spread. Community-associated (CA) MDR bacteria have an antibiotic resistance phenotype that is stable in the absence of antibiotic pressure of the type normally observed in hospitals or nursing homes. An exception to this rule may be those CA-MDR bacteria, of which the prevalence is driven by the presence of antibiotics in the food chain. Additionally, the colonization of otherwise healthy hosts is a common characteristic of CA-MDR bacteria. However, subtle immune deficiencies may still be present in the subjects colonized with specific CA-MDR bacteria. Methicillin-resistant S. aureus (MRSA) is the most prevalent of CA-MDR bacteria. CA-MRSA also has the greatest impact on morbidity and mortality. The main threat on the horizon is represented by Enterobacteriaceae. The production of extended spectrum β-lactamases in Enterobacteriaceae encountered in the community is becoming increasingly prevalent. Of great concern is the potential for the acquisition of carbapenemase genes in CA-Enterobacteriaceae. Prevention of further community spread of MDR bacteria is of the utmost importance, and will require a multi-disciplinary approach involving all stakeholders
The global epidemiology of carbapenemase-producing Enterobacteriaceae
Carbapenemase-producing Enterobacteriaceae (CPE) are an important and increasing threat to global health. Both clonal spread and plasmid-mediated transmission contribute to the ongoing rise in incidence of these bacteria. Among the 4 classes of β-lactamases defined by the Ambler classification system, the carbapenemases that confer carbapenem resistance in Enterobacteriaceae belong to 3 of them: Class A (K. pneumoniae carbapenemases, KPC), Class B (metallo-β-lactamases, MBL including New Delhi metallo-β-lactamases, NDM) and Class D (OXA-48-like carbapenemases). KPC-producing CPE are the most commonly occurring CPE in the United States. MBL-producing CPE have been most commonly associated with the Indian Subcontinent as well as with specific countries in Europe, including Romania, Denmark, Spain, and Hungary. The epicenter of OXA-48-like-producing is in Turkey and surrounding countries. Detailed knowledge of the epidemiology and molecular characteristics of CPE is essential to stem the spread of these pathogens
Ceftazidime/Avibactam and Ceftolozane/Tazobactam: Second-generation β-Lactam/β-Lactamase Inhibitor Combinations
Ceftolozane/tazobactam and ceftazidime/avibactam are 2 novel β-lactam/β-lactamase combination antibiotics. The antimicrobial spectrum of activity of these antibiotics includes multidrug-resistant (MDR) gram-negative bacteria (GNB), including Pseudomonas aeruginosa. Ceftazidime/avibactam is also active against carbapenem-resistant Enterobacteriaceae that produce Klebsiella pneumoniae carbapenemases. However, avibactam does not inactivate metallo-β-lactamases such as New Delhi metallo-β-lactamases. Both ceftolozane/tazobactam and ceftazidime/avibactam are only available as intravenous formulations and are dosed 3 times daily in patients with normal renal function. Clinical trials showed noninferiority to comparators of both agents when used in the treatment of complicated urinary tract infections and complicated intra-abdominal infections (when used with metronidazole). Results from pneumonia studies have not yet been reported. In summary, ceftolozane/tazobactam and ceftazidime/avibactam are 2 new second-generation cephalosporin/β-lactamase inhibitor combinations. After appropriate trials are conducted, they may prove useful in the treatment of MDR GNB infections. Antimicrobial stewardship will be essential to preserve the activity of these agents
Hydroxylation Structure and Proton Transfer Reactivity at the Zinc Oxide-Water Interface
The hydroxylation structural features of the first
adsorption layer and its connection to proton transfer reactivity have been studied for the ZnO-liquid water interface at room temperature. Molecular dynamics simulations employing the ReaxFF forcefield were performed for water on seven ZnO surfaces with varying step concentrations. At higher water coverage a higher level of hydroxylation was found, in agreement with previous experimental results. We have also calculated the free energy barrier for transferring a proton to the surface, showing that stepped surfaces stabilize the hydroxylated
state and decrease the water dissociation barrier. On highly stepped surfaces the barrier is only 2 kJ/mol or smaller. Outside the first adsorption layer no dissociation events were found during almost 100 ns of simulation time; this indicates that these reactions are much more likely if catalyzed by the metal oxide surface. Also, when exposed to a vacuum, the less stepped surfaces stabilize adsorption beyond monolayer coverage
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‘Wish you were here before!’ Who gains from collaboration between computer science and social research?
This short paper summarizes experiences of interdisciplinary research collaboration by the VU-University Amsterdam and The Open University, in the context of an e-infrastructure called Scratchpads
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Social science for e-science in biodiversity research: a position paper on behalf of ViBRANT
The application of e-science, the use of information and communications technologies (ICT) to support scientific work, increases the scale, access and diversity of information and collaborations and enables research on complex and interdisciplinary questions. However, smart technologies alone do not make e-science a success. Insights on the user and usage and the understanding of the societal and organizational dimensions contribute to the design, user uptake and sustainable use of the infrastructure. Hence, social science has a significant contribution to make to the development and implementation of e-science facilities. The position we would like to bring forward to this meeting is based on our experience in the e-infrastructure project, called ViBRANT (http://vbrant.eu). Below we highlight why and how, according to us, social science contributes to ViBRANT, under what conditions and what issues still need attention
The politicization trap and how to escape it: intergovernmentalism, politicization and competences mismatch in perspective
Water adsorption beyond monolayer coverage on ZnO surfaces and nanoclusters
The surface structures of ZnO surfaces and ZnO nanoparticles, with and without water, were studied with a reactive force field (FF) within the ReaxFF framework, and molecular dynamics (MD) simulations. The force field parameters were fitted to a training set of data points (energies, geometries, charges) derived from quantum-mechanical B3LYP calculations. The ReaxFF model predicts structures and reactions paths at a fraction of the computational cost of the quantum-mechanical calculations. Our simulations give the following results for the (10-10) surface. (i) The alternating H-bond pattern of Meyer et al. for one monolayer coverage is reproduced and maintained at higher temperatures. (ii) Coverages beyond one water monolayer enhances ZnO hydroxylation at the expense of ZnO hydration. (iii) This is achieved through an entirely new H-bond pattern mediated via the water molecules in the second layer above the ZnO surface. (iv) During a desorption process, the desorption rate slows significantly when two monolayers remain. Simulations of nanoparticles in water suggest that these conclusions are relevant also in the nano case
Development and Validation of a ReaxFF Reactive Force Field for Cu Cation/Water Interactions and Copper Metal/Metal Oxide/Metal Hydroxide Condensed Phases
To enable large-scale reactive dynamic simulations of copper oxide/water and copper ion/water interactions we have extended the ReaxFF reactive force field framework to Cu/O/H interactions. To this end, we employed a multistage force field development strategy, where the initial training set (containing metal/metal oxide/metal hydroxide condensed phase data and [Cu(H_2O)_n]^(2+) cluster structures and energies) is augmented by single-point quantum mechanices (QM) energies from [Cu(H_2O)_n]^(2+) clusters abstracted from a ReaxFF molecular dynamics simulation. This provides a convenient strategy to both enrich the training set and to validate the final force field. To further validate the force field description we performed molecular dynamics simulations on Cu^(2+)/water systems. We found good agreement between our results and earlier experimental and QM-based molecular dynamics work for the average Cu/water coordination, Jahn−Teller distortion, and inversion in [Cu(H_2O)_6]^(2+) clusters and first- and second-shell O−Cu−O angular distributions, indicating that this force field gives a satisfactory description of the Cu-cation/water interactions. We believe that this force field provides a computationally convenient method for studying the solution and surface chemistry of metal cations and metal oxides and, as such, has applications for studying protein/metal cation complexes, pH-dependent crystal growth/dissolution, and surface catalysis
An Overview of COVID-19 in solid organ transplantation
Background The COVID-19 pandemic has influenced the field of solid organ transplantation (SOT) in many ways. COVID-19 has led to programmatic impacts and changes in donor and recipient selection. Several studies have evaluated the course, optimal treatment, and prevention of COVID-19 in SOT recipients. Objective To review the literature on COVID-19 in SOT recipients. Sources PubMed, Web of Science, and Google Scholar were searched. The search was restricted to articles published between January 1, 2019, and December 1, 2021. Content The COVID-19 pandemic initially led to a decreased volume of solid organ transplants. However, transplant volumes at most centers have rebounded. Donor selection remains an incompletely defined issue. Several reports suggests that donor-derived SARS-CoV-2 infections occur only in lung transplant recipients, and that other organs from SARS-CoV-2 PCR-positive donors could potentially be safely used. However, these data are limited to case series. Transplantation for end-stage lung disease after COVID-19 infection is increasingly common and has been performed with acceptable outcomes. In acute COVID-19 in a transplant candidate, transplantation should be delayed when feasible. After adjustment, mortality after COVID-19 appear similar in SOT recipients as compared to the general population, with notable increased use of anti-viral and anti-inflammatory treatment options. Prevention of COVID-19 is key in SOT recipients. Vaccination of SOT recipients and anyone who is in contact with SOT recipients is one of the cornerstones of prevention. Non-pharmacological interventions such as face coverings, hand hygiene, and physical distancing remain ever important as well. Implications The COVID-19 pandemic continues to have an important impact on SOT candidates and recipients. Prevention of infection is the most important measure, and requires careful attention to approaches to vaccination, and messaging of the ongoing need for face coverings, physical distancing, and hand hygiene
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