Biofilm control strategies: Engaging with the public

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. There are few peer-reviewed publications about public engagement with science that are written by microbiologists; those that exist tend to be a narrative of an event rather than a hypothesis-driven investigation. However, it is relatively easy for experienced scientists to use a scientific method in their approach to public engagement. This short communication describes three public engagement activities hosted by the authors, focused on biofilm control: hand hygiene, plaque control and an externally applied antimicrobial coating. In each case, audience engagement was assessed using quantitative and/or qualitative methods. A critical evaluation of the findings enabled the construction of a public engagement ‘tick list’ for future events that would enable a hypothesis-driven approach with more effective communication activities and more robust evaluation

Rapid screening of the antimicrobial efficacy of Ag zeolites

A semi-quantitative screening method was used to compare the killing efficacy of Ag zeolites against bacteria and yeast as a function of the zeolite type, crystal size and concentration. The method, which substantially reduced labor, consumables and waste and provided an excellent preliminary screen, was further validated by quantitative plate count experiments. Two pairs of zeolite X and zeolite beta with different sizes (ca. 200 nm and 2 m for zeolite X and ca. 250 and 500 nm for zeolite beta) were tested against Escherichia coli (E. coli) and Candida albicans (C. albicans) at concentrations in the range 0.05–0.5 mg ml−1. Reduction of the zeolite crystal size resulted in a decrease in the killing efficacy against both microorganisms. The semi-quantitative tests allowed convenient optimization of the zeolite concentrations to achieve targeted killing times. Zeolite beta samples showed higher activity compared to zeolite X despite their lower Ag content, which was attributed to the higher concentration of silver released from zeolite beta samples. Cytotoxicity measurements using peripheral blood mononuclear cells (PBMCs) indicated that Ag zeolite X was more toxic than Ag zeolite beta. However, the trends for the dependence of cytotoxicity on zeolite crystal size at different zeolite concentrations were different for the two zeolites and no general conclusions about zeolite cytotoxicity could be drawn from these experiments. This result indicates a complex relationship, requiring the necessity for individual cytotoxicity measurements for all antimicrobial applications based on the use of zeolites

The effect of dentifrice abrasion on denture topography and the subsequent retention of microorganisms on abraded surfaces

Statement of problem. Denture surfaces provide hard nonshedding niches for the adhesion and subsequent accumulation of oral microorganisms into denture plaque, which can harbor various potential pathogens linked with oral mucosal lesions and inhalation pneumonia. The initial adhesion is the prerequisite for subsequent biofilm growth, and surface roughness niches facilitate this process by trapping cells. Retained microorganisms are then able to proliferate when the denture is returned to the oral cavity.Purpose. The purpose of this study was to measure the amount and strength of the attachment of microorganisms to a roughened denture acrylic resin surface. An increase in surface roughness increases the retention of microorganisms and a greater amount of cell-surface contact interface may increase the strength of adhesion and, therefore, retention. Cleaning denture surfaces with brushes and dentifrices can influence the denture surface topography and, therefore, may affect retention.Material and methods. Denture acrylic resin specimens were abraded to provide different surface roughness. The amount of attachment of Streptococcus oralis or Candida albicans to these surfaces was assessed by measuring the area of a microscopic field covered by stained cells after 1 hour of incubation. The strength of attachment was assessed with atomic force microscopy, whereby an increasing force was applied to the attached cells until they detached from the surface.Results. Both bacteria and yeast cells were retained in increasing amounts on surfaces of increasing roughness. Cells were most strongly attached on surfaces whose linear features (scratches) were of comparable size with the cells (the streptococci on the low-abraded surfaces, and the yeast on high-abraded surfaces).Conclusion. Analysis of findings reveal that even small abrasions may enhance retention on denture surfaces and reduce surface cleanability. The strength of attachment instead of the amount is more important in terms of surface hygiene. © 2014 Editorial Council for the Journal of Prosthetic Dentistry

Application of Cu-FAU nanozeolites for decontamination of surfaces soiled with the ESKAPE pathogens

Antimicrobial resistance is a global threat with catastrophic forecasts in terms of human and economic losses. The so-called ESKAPE pathogens (Enterococcus species, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa and Enterobacter species) represent a range of species of particular concern because they cause many serious hospital infections, and can show resistance toward available commercial antibiotics. Copper-containing zeolite nanocrystals (10e30 nm) with FAU-type structure (Cu-FAU), in the form of stable colloidal suspensions, were prepared at high yield in the absence of organic templates and studied for their activity against ESKAPE microorganisms. The materials were active against all six ESKAPE species. The survival of Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa on stainless-steel coupons after direct treatment with the CuFAU zeolite suspensions was determined quantitatively. Complete decontamination (5-log reduction in bacterial counts) was achieved within 20 min for P. aeruginosa, and within 10 min for the K. pneumoniae and S. aureus. This result is significant, particularly for sanitization of surfaces in healthcare settings, with the potential to initiate a new direction of research to help address the global antimicrobial resistance threat

The denture microbiome in health and disease: an exploration of a unique community

The United Nations suggests the global population of denture wearers (an artificial device that acts as a replacement for teeth) is likely to rise significantly by the year 2050. Dentures become colonized by microbial biofilms, the composition of which is influenced by complex factors such as patient’s age and health, and the nature of the denture material. Since colonization (and subsequent biofilm formation) by some micro-organisms can significantly impact the health of the denture wearer, the study of denture microbiology has long been of interest to researchers. The specific local and systemic health risks of denture plaque are different from those of dental plaque, particularly with respect to the presence of the opportunist pathogen Candida albicans and various other nonoral opportunists. Here, we reflect on advancements in our understanding of the relationship between micro-organisms, dentures, and the host, and highlight how our growing knowledge of the microbiome, biofilms, and novel antimicrobial technologies may better inform diagnosis, treatment, and prevention of denture-associated infections, thereby enhancing the quality and longevity of denture wearers

The effect of surface properties of polycrystalline, single phase metal coatings on bacterial retention

In the food industry microbial contamination of surfaces can result in product spoilage which may lead to potential health problems of the consumer. Surface properties can have a substantial effect on microbial retention. The surface characteristics of chemically different coatings (Cu, Ti, Mo, Ag, Fe) were defined using white light profilometry (micro-topography and surface features), atomic force microscopy (nano-topography) and physicochemical measurements. The Ag coating had the greatest topography measurements and Fe and Mo the least. Mo was the most hydrophobic coating (lowest γAB,γ+, γ−) whilst Ag was the most hydrophilic (greatest γAB,γ+, γ−). The physicochemical results for the Fe, Ti and Cu coatings were found to lie between those of the Ag and Mo coatings. Microbiological retention assays were carried out using Listeria monocytogenes, Escherichia coli and Staphylococcus aureus in order to determine how surface properties influenced microbial retention. It was found that surface chemistry had an effect on microbial retention, whereas the shape of the surface features and nano-topography did not. L. monocytogenes and S. aureus retention to the surfaces were mostly affected by surface micro-topography, whereas retention of E. coli to the coatings was mostly affected by the coating physicochemistry. There was no trend observed between the bacterial cell surface physicochemistry and the coating physicochemistry. This work highlights that different surface properties may be linked to factors affecting microbial retention hence, the use of surface chemistry, topography or physicochemical factors alone to describe microbial retention to a surface is no longer adequate. Moreover, the effects of surface parameters on microbial retention should be considered individually for each bacterial genus

Quantifying the pattern of microbial cell dispersion, density and clustering on surfaces of differing chemistries and topographies using multifractal analysis

The effects of surface topography on bacterial distribution across a surface are of extreme importance when designing novel, hygienic or antimicrobial surface coatings. The majority of methods that are deployed to describe the pattern of cell dispersion, density and clustering across surfaces are currently qualitative. This paper presents a novel application of multifractal analysis to quantitatively measure these factors using medically relevant microorganisms (Staphylococcus aureus or Staphylococcus epidermidis). Surfaces (medical grade 316 stainless steel) and coatings (Ti–ZrN, Ti–ZrN/6.0%Ag, Ti–ZrN/15.6%Ag, TiZrN/24.7%Ag) were used in microbiological retention assays. Results demonstrated that S. aureus displayed a more heterogeneous cell dispersion (∆αAS < 1) whilst the dispersion of S. epidermidis was more symmetric and homogeneous (∆αAS ≥ 1). Further, although the surface topography and chemistry had an effect on cell dispersion, density and clustering, the type of bonding that occurred at the surface interface was also important. Both types of cells were influenced by both surface topographical and chemical effects; however, S. aureus was influenced marginally more by surface chemistry whilst S. epidermidis cells was influenced marginally more by surface topography. Thus, this effect was bacterially species specific. The results demonstrate that multifractal analysis is a method that can be used to quantitatively analyse the cell dispersion, density and clustering of retained microorganisms on surfaces. Using quantitative descriptors has the potential to aid the understanding the effect of surface properties on the production of hygienic and antimicrobial coatings

Seeing the baby, doing family: commercial ultrasound as family practice?

Medical sociologists and anthropologists have studied the social significance of obstetric ultrasound for families but little is known about how women and families make use of commercially available ultrasound scans. This article draws on interviews with women who booked a scan with a commercial company in the UK. For some women, commercial ultrasound can be understood as a family practice. We investigate this theme by examining who accompanies women to commercial scan appointments, how scan images are shared and how sonograms are used as prompts to resemblance talk. We argue that commercial scans are more than an additional opportunity to acquire ‘baby’s first picture’ and offer a flexible resource to do family, creating and affirming family relationships and rehearsing roles as parents, siblings and grandparents. Our findings confirm the importance of imagination in doing family and raise questions about the role of technology and commercial interests in shaping family practices

China’s Weibo: is faster different?

The popularization of microblogging in China represents a new challenge to the state’s regime of information control. The speed with which information is diffused in the microblogosphere has helped netizens to publicize and express their discontent with the negative consequences of economic growth, income inequalities and official corruption. In some cases, netizen led initiatives have facilitated the mobilization of online public opinion and forced the central government to intervene to redress acts of lower level malfeasance. However, despite the growing corpus of such cases, the government has quickly adapted to the changing internet ecology and is using the same tools to help it maintain control of society by enhancing its claims to legitimacy, circumscribing dissent, identifying malfeasance in its agents and using online public opinion to adapt policy and direct propaganda efforts. This essay reflects on microblogging in the context of the Chinese internet, and argues that successes in breaking scandals and mobilizing opinion against recalcitrant officials should not mask the reality that the government is utilizing the microblogosphere to its own advantage