Surface modification of platelet concentrate bags to reduce biofilm formation and transfusion sepsis.

Bacterial contamination of blood products poses a major risk in transfusion medicine, including transfusions involving platelet products. Although testing systems are in place for routine screening of platelet units, the formation of bacterial biofilms in such units may decrease the likelihood that bacteria will be detected. This work determined the surface properties of p-PVC platelet concentrate bags and investigated how these characteristics influenced biofilm formation. Serratia marcescens and Staphylococcus epidermidis, two species commonly implicated in platelet contamination, were used to study biofilm growth. The platelet concentrate bags were physically flattened to determine if reducing the surface roughness altered biofilm formation. The results demonstrated that the flattening process of the platelet bags affected the chemistry of the surface and reduced the surface hydrophobicity. Flattening of the surfaces resulted in a reduction in biofilm formation for both species after 5 days, with S. marcescens demonstrating a greater reduction. However, there was no significant difference between the smooth and flat surfaces following 7 days’ incubation for S. marcescens and no significant differences between any of the surfaces following 7 days’ incubation for S. epidermidis. The results suggest that flattening the p-PVC surfaces may limit potential biofilm 2 formation for the current duration of platelet storage time of 5 days. It is hoped that this work will enhance the understanding of how surface properties influence the development of microbial biofilms in platelet concentrate bags in order to devise a solution to discourage biofilm formation

The Effect of Human Blood Plasma Conditioning Films on Platelet Transfusion Bag Surface Properties

Transfusion-associated bacterial infections continue to occur which may be due to the formation of bacterial biofilms on the inner surface of the blood bag. Plasticized poly (vinyl chloride) (p-PVC) platelet storage bags in three surface roughness states (rough, smooth and flattened) were used to determine the effect that a conditioning film (CF) of human plasma had on surface properties and its interaction with Staphylococcus epidermidis and Serratia marcescens. SEM and optical profilometry determined changes in surface roughness, whilst EDX and ATR-FTIR determined surface chemistry. The physicochemistry of the surfaces and bacteria was assessed using contact angle measurements and MATH assays respectively. When applied to a rougher surface, the CF reduced the surface topography, masked certain surface chemistry features and made the surfaces more hydrophilic. The CF reduced the adhesion of the bacteria to most of the hydrocarbons. When human plasma was combined with bacteria, most of the physicochemical properties changed similarly to those of human plasma alone, with the most significant changes observed after 24 h especially with Ser. marcescens. The results demonstrated that the presence of human plasma had a significant effect on the surface properties of the platelet bags and also on microbial interactions with the bag surface

Differential engulfment of staphylococcus aureus and pseudomonas aeruginosa by monocyte-derived macrophages is associated with altered phagocyte biochemistry and morphology

© 2020, Leibniz Research Centre for Working Environment and Human Factors. All rights reserved. Knowledge of changes in macrophages following bacterial engulfment is limited. U937-derived macrophages were incubated with Staphylococcus aureus or Pseudomonas aeruginosa. Morphological and biochemical changes in macrophages following host-pathogen interactions were visualized using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR) respectively. Principal Component Analysis (PCA) was used to assess the variability in the FTIR spectra. Following host-pathogen interactions, survival of S. aureus was significantly lower than P. aeruginosa (P 99 % of variability in the FTIR spectra explained by the first two principal components. These findings demonstrated that there were clear morphological and biochemical changes in macrophages following engulfment of two different bacterial types suggesting that the biochemical components of the bacterial cell wall influenced the biochemical characteristics and hence the morphology of macrophages in distinct ways

Author Correction: Antimicrobial activity of Ti-ZrN/Ag coatings for use in biomaterial applications.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper

Poly(para-Phenylene Ethynylene) (PPE)- and Poly(para-Phenylene Vinylene) (PPV)-Poly[(2-(Methacryloyloxy)Ethyl) Trimethylammonium Chloride] (PMETAC) Graft Copolymers Exhibit Selective Antimicrobial Activity

Antimicrobial resistance is becoming a global health concern; as such, the need for new effective treatments and preventive measures is increasing. Poly(para-phenylene ethynylene) (PPE)- and poly(para-phenylene vinylene) (PPV)-poly[(2-(methacryloyloxy)ethyl) trimethylammonium chloride] (PMETAC) graft copolymers were tested against a range of clinically and industrially relevant bacteria and results showed many of these conjugated polyelectrolytes (CPE’s) to be active. Of all of the compounds tested, PPE-g-PMETAC (low molecular weight, LMW) had greatest antimicrobial activity, especially against Enterococcus faecium, Methicillin resistant Staphylococcus aureus (MRSA), Escherichia coli and Acinetobacter baumannii

The effects of blood conditioning films on the antimicrobial and retention properties of zirconium-nitride silver surfaces

External bone fixation devices provide support and rehabilitation for severely damaged/broken bones, however, this invasive procedure is prone to infection. Zirconium nitride/silver (Ti-ZrN/Ag) coatings were characterised for surface topography, chemical composition, physicochemistry and antimicrobial efficacy (against Staphylococcus aureus and Staphylococcus epidermidis), in the presence of a blood conditioning film. The conditioning film altered the width of the microtopography of the surfaces however, the depth of the features remained relatively constant. The conditioning film also altered the coatings from hydrophobic to hydrophilic/partially hydrophilic surfaces. Following the MATH assay, the presence of a conditioning film reduced affinity towards the hydrocarbons for both microorganisms. The addition of a blood conditioning film reduced the antimicrobial efficacy of the Ti-ZrN/Ag coatings but also reduced the number of retained bacteria. This study suggests that the presence of a pre-defined blood conditioning film may result in surfaces with anti-adhesive properties, potentially leading to a reduction in bacterial retention. This, combined with the antimicrobial efficacy of the coatings, could reduce the risk of infection on biomaterial surfaces

Effectiveness of titanium nitride silver coatings against Staphylococcus spp. in the presence of BSA and whole blood conditioning agents

Implanted medical devices are at risk of developing an infection at the surgical site. Once a medical implant is inserted, it initially becomes coated by a conditioning film, followed by bacterial retention. In the present study, medical grade stainless steel substrata were coated with titanium nitride (TiN) or titanium nitride/silver (TiN/14.94 at.%Ag or TiN/19.04 at.%Ag). Surface analysis determined that with increased silver concentration, silver nanoparticles were heterogeneously distributed throughout the coatings. The effect of bovine serum albumin or whole blood conditioning agents on the antimicrobial activity and microbial retention were determined using Staphylococcus aureus or Staphylococcus epidermidis. The presence of the conditioning agents reduced the antimicrobial effect of the surfaces against S. aureus. When the cells and conditioning agents were applied together, a reduction in bacterial retention and conditioning film was observed. These results suggest that the impact of conditioning agents should be considered since conditioning films may reduce bacterial retention but may also decrease the antimicrobial properties of the surface coatings

Release of oxidizing fluids in subduction zones recorded by iron isotope zonation in garnet

Subduction zones are key regions of chemical and mass transfer between the Earth’s surface and mantle. During subduction, oxidized material is carried into the mantle and large amounts of water are released due to the breakdown of hydrous minerals such as lawsonite. Dehydration accompanied by the release of oxidizing species may play a key role in controlling redox changes in the subducting slab and overlying mantle wedge. Here we present measurements of oxygen fugacity, using garnet–epidote oxybarometry, together with analyses of the stable iron isotope composition of zoned garnets from Sifnos, Greece. We find that the garnet interiors grew under relatively oxidized conditions whereas garnet rims record more reduced conditions. Garnet δ56Fe increases from core to rim as the system becomes more reduced. Thermodynamic analysis shows that this change from relatively oxidized to more reduced conditions occurred during lawsonite dehydration. We conclude that the garnets maintain a record of progressive dehydration and that the residual mineral assemblages within the slab became more reduced during progressive subduction-zone dehydration. This is consistent with the hypothesis that lawsonite dehydration accompanied by the release of oxidizing species, such as sulfate, plays an important and measurable role in the global redox budget and contributes to sub-arc mantle oxidation in subduction zones

Measuring socio-demographic differences in volunteers with a value-based index: illustration in a mega event

The phenomenon of volunteering can be analysed as a consumer experience through the concept of value as a trade-off between benefits and costs. In event volunteering, both the expected value (pre-experienced) and the perceived value (post-experienced) of volunteering can be assessed. With this purpose, an online quantitative survey is conducted with a sample of 711 volunteers in a religious mega event, with questions related to five dimensions of their experience: efficiency, social value, play, spirituality and time spent. These five scales, properly tested are used for building a multidimensional index of both the expected and perceived value of the volunteer experience. ANOVAs test show significant differences on the index in both moments upon the socio-demographic profiles: negative expectations/experience balance by age, contrasted results by sex, and more experienced volunteers being more critical with the value experienced. Implications for event managers are proposed, in line with the motivation of volunteers

Sharing vocabularies: towards horizontal alignment of values-driven business functions

This paper highlights the emergence of different ‘vocabularies’ that describe various values-driven business functions within large organisations and argues for improved horizontal alignment between them. We investigate two established functions that have long-standing organisational histories: Ethics and Compliance (E&C) and Corporate Social Responsibility (CSR). By drawing upon research on organisational alignment, we explain both the need for and the potential benefit of greater alignment between these values-driven functions. We then examine the structural and socio-cultural dimensions of organisational systems through which E&C and CSR horizontal alignment can be coordinated to improve synergies, address tensions, and generate insight to inform future research and practice in the field of Business and Society. The paper concludes with research questions that can inform future scholarly research and a practical model to guide organizations’ efforts towards inter-functional, horizontal alignment of values-driven organizational practice