A. Prysor Williams

The role of the natural environment in the emergence of antibiotic resistance in Gram-negative bacteria

During the past 10 years, multidrug-resistant Gram-negative Enterobacteriaceae have become a substantial challenge to infection control. It has been suggested by clinicians that the effectiveness of antibiotics is in such rapid decline that, depending on the pathogen concerned, their future utility can be measured in decades or even years. Unless the rise in antibiotic resistance can be reversed, we can expect to see a substantial rise in incurable infection and fatality in both developed and developing regions. Antibiotic resistance develops through complex interactions, with resistance arising by de-novo mutation under clinical antibiotic selection or frequently by acquisition of mobile genes that have evolved over time in bacteria in the environment. The reservoir of resistance genes in the environment is due to a mix of naturally occurring resistance and those present in animal and human waste and the selective effects of pollutants, which can co-select for mobile genetic elements carrying multiple resistant genes. Less attention has been given to how anthropogenic activity might be causing evolution of antibiotic resistance in the environment. Although the economics of the pharmaceutical industry continue to restrict investment in novel biomedical responses, action must be taken to avoid the conjunction of factors that promote evolution and spread of antibiotic resistance.

The environmental and biosecurity characteristics of livestock carcass disposal methods: A review

Livestock mortalities represent a major waste stream within agriculture. Many different methods are used throughout the world to dispose of these mortalities; however within the European Union (EU) disposal options are limited by stringent legislation. The legal disposal options currently available to EU farmers (primarily rendering and incineration) are frequently negatively perceived on both practical and economic grounds. In this review, we assess the potential environment impacts and biosecurity risks associated with each of the main options used for disposal of livestock mortalities in the world and critically evaluate the justification for current EU regulations. Overall, we conclude that while current legislation intends to minimise the potential for on-farm pollution and the spread of infectious diseases (e.g. transmissible spongiform encephalopathies, bacterial pathogens), alternative technologies (e.g. bioreduction, anaerobic digestion) may provide a more cost-effective, practical and biosecure mechanism for carcass disposal as well as having a lower environmental footprint. Further social, environmental and economic research is therefore warranted to assess the holistic benefits of alternative approaches for carcass disposal in Europe, with an aim to provide policy-makers with robust knowledge to make informed decisions on future legislation.

Heat and lime-treatment as effective control methods for E. coli O157:H7 in organic wastes

Land-application of abattoir wastes is economically appealing and may provide an effective means of closing the nutrient cycling loop. This practise is constrained, however, by legislation which necessitates pre-treatment to remove pathogenic micro-organisms prior to land-spreading. Here we investigated whether heat-treatment or lime addition could eliminate Escherichia coli O157:H7 from three contrasting abattoir wastes. We found that treatment at 60 degrees C for 10 min effectively eradicated the organism while treatment for the same length of time at 50 degrees C led to 2-4 log reductions, but not a complete kill. Temperatures of 72 degrees C induced waste solidification rendering its use impractical. The potential for re-growth in heat-treated and untreated wastes was also investigated. Survival was significantly greater in heat-treated wastes, although the difference was less than half a log unit in magnitude. This effect of heat-treatment on pathogen survival appeared to be ameliorated when wastes were mixed with soil. No viable E. coli O157:H7 cells were recovered from any waste after application of lime (CaO) at a rate of 10 gl(-1), even after enrichment. Our results indicate that pasteurisation-style or liming treatments may provide a suitable alternative method for reducing pathogen loads in abattoir wastes, so that they can be applied to land with minimal biological risk.

Fate of pathogens in a simulated bioreduction system for livestock carcasses

The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after 3months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal.

Subclinical infection and asymptomatic carriage of gastrointestinal zoonoses: Occupational exposure, environmental pathways, and the anonymous spread of disease

Asymptomatic carriage of gastrointestinal zoonoses is more common in people whose profession involves them working directly with domesticated animals. Subclinical infections (defined as an infection in which symptoms are either asymptomatic or sufficiently mild to escape diagnosis) are important within a community as unknowing (asymptomatic) carriers of pathogens do not change their behaviour to prevent the spread of disease; therefore the public health significance of asymptomatic human excretion of zoonoses should not be underestimated. However, optimal strategies for managing diseases where asymptomatic carriage instigates further infection remain unresolved, and the impact on disease management is unclear. In this review we consider the environmental pathways associated with prolonged antigenic exposure and critically assess the significance of asymptomatic carriage in disease outbreaks. Although screening high-risk groups for occupationally acquired diseases would be logistically problematical, there may be an economic case for identifying and treating asymptomatic carriage if the costs of screening and treatment are less than the costs of identifying and treating those individuals infected by asymptomatic hosts.

Bioreduction of Sheep Carcasses Effectively Contains and Reduces Pathogen Levels under Operational and Simulated Breakdown Conditions

Options for the storage and disposal of animal carcasses are extremely limited in the EU after the introduction of the EU Animal By-products Regulations (ABPR; EC/1774/2002), leading to animosity within the livestock sector and the call for alternative methods to be validated. Novel storage technologies such as bioreduction may be approved under the ABPR provided that they can be shown to prevent pathogen proliferation. We studied the survival of Enterococcus faecalis, Salmonella spp., E. coli O157 and porcine parvovirus in bioreduction vessels containing sheep carcasses for approximately 4 months. The vessels were operated under two different scenarios: (A) where the water within was aerated and heated to 40 °C, and (B) with no aeration or heating, to simulate vessel failure. Microbial analysis verified that pathogens were contained within the bioreduction vessel and indeed reduced in numbers with time under both scenarios. This study shows that bioreduction can provide an effective and safe on-farm storage system for livestock carcasses prior to ultimate disposal. The findings support a review of the current regulatory framework so that bioreduction is considered for approval for industry use within the EU.

Delineating and mapping riparian areas for ecosystem service assessment

Riparian buffers, the interface between terrestrial and freshwater ecosystems, have the potential to protect water bodies from land-based pollution, and also for enhancing the delivery of a range of ecosystem services. The UK currently has no defined optimal width or maximum extent of riparian buffers for specific ecosystem services. Here, we present the first study, which attempts to (a) compare and critique different riparian buffer delineation methods and (b) investigate how ecological processes, for example, pollutant removal, nutrient cycling, and water temperature regulation, are affected spatially by proximity to the river and also within a riparian buffer zone. Our results have led to the development of new concepts for riparian delineation based on ecosystem service-specific scenarios. Results from our study suggest that choice of delineation method will influence not only the total area of potential riparian buffers but also the proportion of land cover types included, which in turn will determine their main ecosystem provision. Thus, for some ecological processes (e.g., pollutant removal), a fixed-distance approach will preserve and protect its ecosystem function, whereas for processes such as denitrification, a variable-width buffer will reflect better riparian spatial variability maximizing its ecological value. In summary, riparian delineation within UK habitats should be specific to the particular ecosystem service(s) of interest (e.g., uptake of nutrients and shading), and the effectiveness of the buffer should be ground-truthed to ensure the greatest level of protection.

Quantifying the contribution of riparian soils to the provision of ecosystem services

Riparian areas, the interface between land and freshwater ecosystems, are considered to play a pivotal role in the supply of regulating, provisioning, cultural and supporting services. Most previous studies, however, have tended to focus on intensive agricultural systems and only on a single ecosystem function. Here, we present the first study which attempts to assess a wide range of ecological processes involved in the provision of the ecosystem service of water quality regulation across a diverse range of riparian typologies. Specifically, we focus on 1) evaluating the spatial variation in riparian soils properties with respect to distance with the river and soil depth in contrasting habitat types; 2) gaining further insights into the underlying mechanisms of pollutant removal (i.e. pesticide sorption/degradation, denitrification, etc.) by riparian soils; and 3) quantify and evaluate how riparian vegetation across different habitat types contribute to the provision of watercourse shading. All the habitats were present within a single large catchment and included: (i) improved grassland, (ii) unimproved (semi-natural) grassland, (iii) broadleaf woodland, (iv) coniferous woodland, and (iv) mountain, heath and bog. Taking all the data together, the riparian soils could be statistically separated by habitat type, providing evidence that they deliver ecosystem services to differing extents. Overall, however, our findings seem to contradict the general assumption that soils in riparian area are different from neighbouring (non-riparian) areas and that they possess extra functionality in terms of ecosystem service provision. Watercourse shading was highly habitat specific and was maximal in forests (ca. 52% shade cover) in comparison to the other habitat types (7-17%). Our data suggest that the functioning of riparian areas in less intensive agricultural areas, such as those studied here, may be broadly predicted from the surrounding land use, however, further research is required to critically test this across a wider range of ecosystems.

Survival and metabolic activity of lux -marked Escherichia coli O157:H7 in different types of milk

Escherichia coli O157:H7 is a potentially lethal pathogen which has been responsible for several outbreaks of milk-borne illness in recent years. The objective of this study was to evaluate the survival and metabolic activity (indexed by bioluminescence) of a chromosomally lux-marked strain of Esch. coli O157:H7 in raw, pasteurized and microfiltered pasteurized milk at 4 and 20°C for up to 14 d. Results showed that the population of Esch. coli O157:H7 and its metabolic activity decreased in all samples during storage at 4°C, with no significant differences in numbers observed between the different milk types; but metabolic activity was significantly higher (P<0·05) in the microfiltered pasteurized milk than that in raw milk. At 20°C, Esch. coli O157:H7 counts and cell activity peaked at day 2, and then declined progressively. At 20°C, survival and metabolic activity were significantly lower in raw milk compared with pasteurized milk. We conclude that storage temperature is more important in regulating the survival of Esch. coli O157 in contaminated milk than its origin/pre-treatment conditions.

Changes to populations might aid the spread antibiotic resistance in the environment

S (Ag) and zinc oxide (ZnO) nanoparticles were simultaneously deposited on a glass substrate using the radio frequency (RF) sputtering technique at different substrate temperatures. Detailed characterization of the co-sputtered Ag/ZnO thin films were performed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The synthesized thin films were tested with UV-Vis diffuse reflectance spectroscopy to evaluate their optical properties. The obtained SEM results show a uniform dispersion of Ag nanoparticles within the ZnO matrix. These nanoparticles have average particle size of 20 nm. The optical band gap value had been calculated from UV transmission spectra of Ag/ZnO thin films deposited at various substrate temperatures. This value was observed to be in the visible light range (i.e. 2.7-3.1 eV), which is much smaller than that of pure ZnO (3.37eV). The photocatalytic activity of the produced thin films was evaluated through visible light photo degradation of 2-chlorophenol (2-CP) which, has been used as a pollutant model in water. The synthesized thin films showed enhanced visible light photocatalytic efficiency towards 2-CP degradation at elevated substrate temperature and retained its catalytic efficiency with only 8% loss in efficiency after four reuse cycles. Kinetic parameters involved in the degradation process were investigated by applying pseudo-second-order kinetic model.T study exposes the extent of contaminations and natural disturbance in soil and tobacco (Nicotiana tabacum) crops with potential health and ecological impacts caused by metals contaminated industrial waste water to surrounding environment. By exploring the extent of metals contamination the study find out the role of geochemical, geostatistical and geospatial inter and intra elemental relationship in soil and tobacco crops. By exploring the relation between and soil and Tobacco crops, a total of 51 samples were collected, pass through acid digestion and analyzed for thirteen major and toxic metals through atomic absorption spectroscopy (AAS 700). Geochemical results showed that the concentration of major and toxic elements in target area was exotically higher than the background areas (control area) with possible percentile (%) variations of 65.7, 27.5, 72.8, 7.5, 56.7, 54.26 23.95, 31.56, 39.3, 22.04, 48.92, 34.11 and 42.6 for Chromium, Cadmium, lead, Nickle, Copper, Zinc, Cobalt, Iron, Manganese, Magnesium, Sodium, Calcium and Potassium respectively. Meanwhile transfer ratio from soil to tobacco crops are 1.64, 5.99, 3.39, 7.59, 7.40, 6.01, 9.29, 1.12, 13.72, 16.37, 1.7, 7.72 and 36.56 (%) respectively. By integrating geochemical and geospatial analysis hereby provide a mobility evidence of metals in the environment. Geostatistical techniques provide scientific evidence and magnitude of toxic and major elements in soils and tobacco crops. All the geostatistical techniques are coherent with each other and can +90 % reliable, except enrichment factor, which were not compatible with these methods. However geospatial analysis proved the mobility of metals in environment. Thus geochemical, geostatistical and geospatial analysis show that industrial discharge are responsible for hyper accumulation of major and toxic elements in soils and tobacco crops and their mobility causes severe ecological and health problems. The study recommends the prohibition of tobacco cultivation and processing. It calls for regular supervision of industrial contamination and its instant remediation through national and international agencies thereby reducing soil contaminations through economic feasibility and in a reasonable time frame.V organic compounds (VOCs) have a variety of negative impacts on human health, some (e.g. benzene and formaldehyde) are known to be human carcinogen. There is, therefore, often a pressing requirement to monitor these compounds. However, monitoring them is not straightforward as their concentrations vary with environmental parameters such temperature, barometric pressure, and groundwater movement. Because of this, the sampling frequency that is used at present is ineffective for determining their representative concentration, therefore, a device which can be left in-situ to collect high temporal resolution data has been developed. VOCs are measured by PID; however, PID measures aggregate VOC concentration. Because VOCs have differing toxicities and behaviours, individual identification is required; therefore, a sample must be collected. In order to do this, a sorbent material must be used to transfer the sample to the GC-MS for identification. The sorbent material must be appropriate for the range of VOCs and of sufficient capacity for extended exposure. The objectives of the work are therefore to: (i) select an appropriate sorbent for incorporation into a dual measurement VOC monitoring device, then to use the instrument to (ii) derive an optimum monitoring methodology.