Antibiotic and biocide resistance in Salmonella enterica and Escherichia coli 0157

Bacterial resistance to antibiotics and biocides is a prevalent problem, which may be exacerbated by the commonplace and often unnecessary inclusion of biocides into domestic products. Addition of antimicrobials, to domestic disinfectants has raised concern about promoting microbial resistance and potential cross-resistance to therapeutic antibiotics. This study investigated the potential for resistance in Salmonella enterica serovars Enteritidis, Typhimurium, Virchow and Escherichia call 0157 to commonly used biocides, to identify mechanisms underlying resistance and whether these provided cross-resistance to antibiotics. Salmonella enterica and E. coli 0157 strains were serially exposed to sub-inhibitory. concentrations of erythromycin (ERY), benzalkonium chloride (BKC), chlorhexidine hydrochloride (CHX)and triclosan (TLN). Once resistance was achieved permeability changes in the outer membrane, including LPS, cell surface charge and hydrophobicityand the presence of,an active efflux were investigated as possible resistance candidates. Thin layer chromatography (TLC) and Gas chromatography (GC) were carried out to examine fatty acid and lipid changes in E. coli 0157 isolates with reduced susceptibility to TLN. Cross-resistance was studied by the Stoke's method and standard microdilution assays. Examination of the outer membrane proteins and LPS did not reveal any significant changes between parent and resistant strains. The hydrophobicity of the cells increased as the cells were passaged and became less. susceptible. An active efflux system was the most likely mechanism of resistance in all strains tested and a fab1 mutation was associated with E. coli 0157 resistant to TLN isolates. In all isolates investigated the resistance was stable for over 30 passages in biocide-free media. A high degree of cross-resistance was obtained in TLN-resjstant Escherichia coli 0157 strains, which repeatedly exerted decreased susceptibility to various antimicrobials, including chloramphenicol, erythromycin, imipenem, tetracycline and trimethoprirn:, as well as to various biocides. The results of this laboratory-based investigation suggest that it is possible for microorganisms to become resistant to biocides when repeatedly exposed to sublethal concentrations. This may be especially the case in the domestic environment where administration of biocides is poorly controlled. Eventually it could lead to the undesirable situation of resident strains becoming resistant to disinfection and cross resistant to other antimicrobials.

Studies of the nature of Burkholderia cepacia in cystic fibrosis

Burkholderia cepacia is an opportunistic pathogen that colonises of the lungs of cystic fibrosis (CF) patients, with a frequently fatal outcome. Antibiotic resistance is common and highly transmissible epidemic strains have been described in the UK. 37 B. cepacia isolates from clinical and botanical sources were characterised via metabolic capabilities, antibiotic sensitivity, fatty acid methyl ester (FAME) profiles restriction digest analysis of chromosomal DNA by pulsed-gel electrophoresis (PFGE) (with the use of two separate restriction enzymes) and outer membrane protein (OMP) profiles. This revealed isolates of the UK CF epidemic strain to form a distinct group with a specific OMP profile. Cluster analysis of PFGE and FAME profiles revealed the species Burkholderia gladioli and Burkholderia vietnamiensis to be more closely related to each other and to laboratory strains of B. cepacia than to the CF epidemic strain considered a member of the latter species. The epidemic strain of B. cepacia may therefore be worthy of species definition in its own right. All the strains studied showed a high level of resistance to antibiotics, including the carbapenems. Considering this, carbapenemase production by isolates of B. cepacia was investigated. A metallo-β-lactamase from a clinical strain of B. cepacia was isolated and partially purified of using Cibacron blue F3GA-coupled agarose. The resulting preparation showed a single band of β-lactamase activity (pI 8.45) after analytical isoelectric focusing. The enzyme was particularly effective in the hydrolysis of imipenem. Meropenem, biapenem, cephaloridine, ceftazidime, benzylpenicillin, ampicillin and carbenicillin were hydrolysed at a lower rate. An unusual inhibition profile was noted. Inhibition by the metal ion chelators ethylene diamine tetra acetic acid and o-phenanthroline was reversed by addition of zinc, indicating a metallo-enzyme, whilst >90% inhibition was attainable with 0.1mM concentrations of tazobactam and clavulanic acid. A study of 8 other clinical isolates showed an enzyme of pI 8.45 to be present and inducible by imipenem in each case. This enzyme was assigned PCM-I (Pseudomonas cepacia metalloenzyme I).

Investigation of aspects of reactive gliosis in human astrocytoma cell lines:application for toxicity assessment

The process of astrogliosis, or reactive gliosis, is a typical response of astrocytes to a wide range of physical and chemical injuries. The up-regulation of the astrocyte specific glial fibrillary acidic protein (GFAP) is a hallmark of reactive gliosis and is widely used as a marker to identify the response. In order to develop a reliable, sensitive and high throughput astrocyte toxicity assay that is more relevant to the human response than existing animal cell based models, the U251-MG, U373-MG and CCF-STTG 1 human astrocytoma cell lines were investigated for their ability to exhibit reactive-like changes following exposure to ethanol, chloroquine diphosphate, trimethyltin chloride and acrylamide. Cytotoxicity analysis showed that the astrocytic cells were generally more resistant to the cytotoxic effects of the agents than the SH-SY5Y neuroblastoma cells. Retinoic acid induced differentiation of the SH-SY5Y line was also seen to confer some degree of resistance to toxicant exposure, particularly in the case of ethanol. Using a cell based ELISA for GFAP together with concurrent assays for metabolic activity and cell number, each of the three cell lines responded to toxicant exposure by an increase in GFAP immunoreactivity (GFAP-IR), or by increased metabolic activity. Ethanol, chloroquine diphosphate, trimethyltin chloride and bacterial lipopolysaccharide all induced either GFAP or MTT increases depending upon the cell line, dose and exposure time. Preliminary investigations of additional aspects of astrocytic injury indicated that IL-6, but not TNF-α. or nitric oxide, is released following exposure to each of the compounds, with the exception of acrylamide. It is clear that these human astrocytoma cell lines are capable of responding to toxicant exposure in a manner typical of reactive gliosis and are therefore a valuable cellular model in the assessment of in vitro neurotoxicity.

The campaign to save Croxteth comprehensive: an ethnographic study of a protest movement

This thesis is based on ethnographic research carried out on a Liverpool protest movement which occurred between November, 1980 and July,1983. The protest movement was waged by residents of the working class community of Croxteth Liverpool who wished to retain their state secondary school, Croxteth Comprehensive. The Liverpool City Council voted in favour of closing Croxteth Comprehensive in January, 1981 because of its declining roles. Residents began theIr campaign as soon as they became aware of intentions to close the school at the end of the previous year. The campaIgn itself went through a number of different phases, distinguishable accordIng to the groups of people involved, the strategy and tactics they employed, the ways in which they justified their campaign, and the goals they pursued. In July of 1982 the organisation which led the protest, the Croxteth Community Action Committee, took illegal possession of the school buildings and ran a pilot summer school project. In September of 1982 they opened the school doors for all secondary pupils on the council estate and began running classes, with the help of volunteer teachers. The school was run successfully in this way for the entire 1982/83 school year. By the end of this period the school was officially reinstated by a new Labour Party majorIty on the city council. This thesis presents a comprehensive account of the entire campaign, from its beginning to end. The campaign is analysed in a number of ways: by situating the closure itself in the economic and political conditions of Liverpool in the 1980s, by examining the relation of Croxteth Comprehensive to its community, by describing the conditions in which different groups of people contributed to the campaign and the changes it went through in its use of tactics, and through a close examination of the activities which took place inside the school during its year of occupation. A number of levels of analysis are used in the study. To explain the closure and the early forms of resistance which developed to oppose it, the structural location of the local government of Liverpool in the late 1970s and early 1980s is described. To explain the relationship of the school to its community, the formation of a group of activists and their leaders, and the resources available to the protestors for pursuing their aims, a single-group model of social action is used. To analyse the establishment of social routines and schooling practices within the school during its occupation, action-theoretica1 models are drawn upon., The chapters of literature review and concept analysis with which this thesis begins link these different levels theoretIcalIy through a model of actIon and its conditions. The theoretical framework employed is reviewed in the last chapter. It is one which could be used to study any social movement, and has applications to other social phenomena as well. Lastly various issues within the sociology of education are examined in light of the events which took place in Croxteth Comprehensive, especially the theory of community education.

Representations of voluntary childlessness in the UK Press, 1990-2008

Representations of voluntary childlessness — the declaration by an individual that he or she does not wish to bear or raise children — were studied in 116 articles published in British national newspapers in the period 1990—2008. Media framing analysis was used to examine broad patterns of framing of the topic, identifying four frames: voluntary childlessness as an individual rights issue, as a form of resistance, as a social trend, and as a personal decision. These frames, it is argued, may act as potential ‘scripts’ for newspaper readers who are debating the decision to start a family.

Failure of steel gusset plates

This thesis examines the parameters associated with the failure of triangular steel gusset plates. Eighty two results are presented investigating the position of the applied load, the gusset plate height to length ratio, size, thickness, internal angle and the removal of the inside corner. The thickness of the loaded plate and its influence on the gusset plates failure is also investigated. Twenty two similar gusset plates were tested to investigate the welds connecting the gusset plate to the adjacent loaded and support edges. The experimental results are compared with existing methods, none of which cover all the variables tested. Some methods do not consider buckling and most of those that do are inadequate. Most of the methods do not accurately take account of the load position. An alternative method based on experimental observations is presented for design purposes. The method covers any combination of the variables tested. To test assumptions made in the theoretical work forty seven strut tests took place to investigate buckling characteristics and fifteen special gusset plates were also tested. The gusset plates were found to fail in an elastic-plastic buckling manner. A gusset plate has a specific moment of resistance capacity about it’s inside corner and the ultimate load that can be applied is dependent upon the position of the load relative to the supported edge. There is an optimum height to length ratio for strength and any increase in the internal angle from 90 degrees produces little change in moment capacity. The removal of small portions of the inside corner of a gusset plate has little effect upon its moment capacity. The loaded plate does not provide any significant moment of resistance to the applied load at failure. The main functions of the loaded and supported edge welds is to prevent the gusset plate from slipping from between the plates.

The structural permeability of concrete at cryogenic temperatures

The thesis describes a programme of research designed to identify concretes for application at cryogenic temperature, in particular for storage of Liquefield Natural Gas which is maintained at a temperature of -165oC. The programme was undertaken in two stages. Stage 1 involved screening tests on seventeen concrete mixes to investigate the effects of strength grade (and water/cement ratio), air entrainment, aggregate type and cement type. Four mixes were selected on the basis of low temperature strength, residual strength after thermal cycling and permeability at ambient temperature. In Stage 2 the selected mixes were subjected to a comprehensive range of tests to measure those properties which determine the leak tightness of a concrete tank at temperatures down to -165oC. These included gas permeability; tensile strength, strain capacity, thermal expansion coefficient and elastic modulus, which in combination provide a measure of resistance to cracking; and bond to reinforcement, which is one of the determining factors regarding crack size and spacing. The results demonstrated that the properties of concrete were generally enhanced at cryogenic temperature, with reduced permeability, reduced crack proneness and, by virtue of increased bond to reinforcement, better control of cracking should it occur. Of the concretes tested, a lightweight mix containing sintered PFA aggregate exhibited the best performance at ambient and cryogenic temperature, having appreciably lower permeability and higher crack resistance than normal weight concretes of the same strength grade. The lightweight mix was most sensitive to thermal cycling, but there was limited evidence that this behaviour would not be significant if the concrete was prestressed. Relationships between various properties have been identified, the most significant being the reduction in gas permeability with increasing strain capacity. The structural implications of the changing properties of the concrete have also been considered.

Striving towards a politics of possibility

It stands to reason that critical theorists should be interested in the newest student movements working to challenge the neoliberalisation of higher education. Yet, while these politics are pushing the limits of critical knowledge about the cultivation of new modalities of radical political resistance, their theoretical significance remains marginalised within the academy. While the academic literature is replete with analysis of the long-anticipated ‘crisis of the university’, many professional responses to the most recent privatisation policies have been muted and ambivalent; or, at the very least, hopeful that the trends can be arrested or mitigated by sanctioned operations of professional critique and opposition. In this essay, I suggest that some of the recent work of student activists demonstrates both the contingency of this position and the possibility of cultivating new political subjectivities and critical-experimental modalities of resistance, within and beyond the university.

Beyond all reason:spaces of hope in the struggle for England’s universities

This essay examines how academics and students in England have been primed to comply with a political agenda of “deep” neoliberalization through cumulative processes of institutional and subjective undermining and considers what might be an appropriate logic of critical response. It first describes how the embedding of principles and mechanisms of market governance within academic life has depoliticized methods for critically theorizing and collectively resisting these processes and then explores the work of recent student-led opposition to the British government’s new policies, teasing out some theoretical implications of the logic of occupation being cultivated there. It suggests that by fusing a determination for autonomy with a transgressive cultivation of new forms of thinking and social practice, the occupations illustrate new critical-experimental work in the politics of possibility. The underlying logic thus offers some resources for reimagining modalities of resistance to processes of deep neoliberalization; however, becoming receptive to them may also require a critique of professional academic subjectivities and reevaluation of attachments to existing forms of the university itself.

The effect of innate compliance on the performance of a counterpulsation device

Cardiovascular disease (CVD) continues to be one of the top causes of mortality in the world. World Heart Organization (WHO) reported that in 2004, CVD contributed to almost 30% of death from estimated worldwide death figures of 58 million[1]. Heart failure treatment varies from lifestyle adjustment to heart transplantation; its aims are to reduce HF symptoms, prolong patient survival and minimize risk [2]. One alternative available in the market for HF treatment is Left Ventricular Assist Device (LVAD). Chronic Intermittent Mechanical Support (CIMS) device is a novel (LVAD) heart failure treatment using counterpulsation similar to Intra Aortic Balloon Pumps (IABP). However, the implantation site of the CIMS balloon is in the ascending aorta just distal to aortic valve contrasted with IABP in the descending aorta. Counterpulsation coupled with implantation close to the aortic valve enables comparable flow augmentation with reduced balloon volume. Two prototypes of the CIMS balloon were constructed using rapid prototyping: the straight-body model is a cylindrical tube with a silicone membrane lining with zero expansive compliance. The compliant-body model had a bulging structure that allowed the membrane to expand under native systolic pressure increasing the device’s static compliance to 1.5 mL/mmHg. This study examined the effect of device compliance and vascular compliance on counterpulsating flow augmentation. Both prototypes were tested on a two-element Windkessel model human mock circulatory loop (MCL). The devices were placed just distal to aortic valve and left coronary artery. The MCL mimicked HF with cardiac output of 3 L/min, left ventricular pressure of 85/15 mmHg, aortic pressure of 70/50 mmHg and left coronary artery flow rate of 66 mL/min. The mean arterial pressure (MAP) was calculated to be 57 mmHg. Arterial compliance was set to be1.25 mL/mmHg and 2.5 mL/mmHg. Inflation of the balloon was triggered at the dicrotic notch while deflation was at minimum aortic pressure prior to systole. Important haemodynamics parameters such as left ventricular pressure (LVP), aortic pressure (AoP), cardiac output (CO), left coronary artery flowrate (QcorMean), and dP (Peak aortic diastolic augmentation pressure – AoPmax ) were simultaneously recorded for both non-assisted mode and assisted mode. ANOVA was used to analyse the effect of both factors (balloon and arterial compliance) to flow augmentation. The results showed that for cardiac output and left coronary artery flowrate, there were significant difference between balloon and arterial compliance at p < 0.001. Cardiac output recorded maximum output at 18% for compliant body and stiff arterial compliance. Left coronary artery flowrate also recorded around 20% increase due to compliant body and stiffer arterial compliance. Resistance to blood ejection recorded highest difference for combination of straight body and stiffer arterial compliance. From these results it is clear that both balloon and arterial compliance are statistically significant factors for flow augmentation on peripheral artery and reduction of resistance. Although the result for resistance reduction was different from flow augmentation, these results serves as an important aspect which will influence the future design of the CIMS balloon and its control strategy. References: 1. Mathers C, Boerma T, Fat DM. The Global Burden of disease:2004 update. Geneva: World Heatlh Organization; 2008. 2. Jessup M, Brozena S. Heart Failure. N Engl J Med 2003;348:2007-18.

Agents for change and changed agents:the micro-politics of change and feminism in the academy

This article explores gender politics and processes in the academy and investigates change from the perspectives of feminist academics. In particular, it explores the experiences of women academics attempting to effect change to the gendered status quo of their own institutions. Focusing on micro-politics, the feminist movement is empirically explored in localized spaces of resistance and in the small but significant individual efforts at making changes in academic institutions. The analysis is based on interviews with female academics working in business and management schools and focuses on the challenges for change and how change attempts affect their personal and professional identities. The article explores the range of change strategies that participants use as they try to progress in their academic career while staying true to their feminist values and priorities through both resisting and incorporating dominant discourses of academic work. The analysis highlights such tensions and focuses on a contextualized, bottom-up perspective on change that, unlike more totalizing theorization, takes into account mundane and lived experiences at the level of the individual. © 2012 Blackwell Publishing Ltd.

A dynamic model of the hypoxia-inducible factor 1α (HIF-1α) network

Activation of the hypoxia-inducible factor (HIF) pathway is a critical step in the transcriptional response to hypoxia. Although many of the key proteins involved have been characterised, the dynamics of their interactions in generating this response remain unclear. In the present study, we have generated a comprehensive mathematical model of the HIF-1a pathway based on core validated components and dynamic experimental data, and confirm the previously described connections within the predicted network topology. Our model confirms previous work demonstrating that the steps leading to optimal HIF-1a transcriptional activity require sequential inhibition of both prolyl- and asparaginyl-hydroxylases. We predict from our model (and confirm experimentally) that there is residual activity of the asparaginyl-hydroxylase FIH (factor inhibiting HIF) at low oxygen tension. Furthermore, silencing FIH under conditions where prolyl-hydroxylases are inhibited results in increased HIF-1a transcriptional activity, but paradoxically decreases HIF-1a stability. Using a core module of the HIF network and mathematical proof supported by experimental data, we propose that asparaginyl hydroxylation confers a degree of resistance upon HIF-1a to proteosomal degradation. Thus, through in vitro experimental data and in silico predictions, we provide a comprehensive model of the dynamic regulation of HIF-1a transcriptional activity by hydroxylases and use its predictive and adaptive properties to explain counter-intuitive biological observations.

Institutional contradiction and management control innovation:a field study of total quality management practices in a privatised telecommunications company

The purpose of this paper is to theorise the changes surrounding the introduction of a management control innovation, total quality management (TQM) techniques, within Telecom Fiji Limited. Using institutional theory and drawing on empirical evidence from multiple sources including interviews, discussions and documents, the paper explicates the institutionalization of these TQM practices. The focus of the paper is the micro-processes and practice changes around TQM implementation, rather than the influence of the macro-level structures that are often linked with institutional theory. The change agents used Quality Action Teams and the National Quality Council to introduce new TQM routines. The present study extends the scope of institutional analysis by explaining how institutional contradictions impact to create and make space for institutional entrepreneurs, who in turn, modify existing routines or introduce new routines in fluid organizational environments which also exhibit evidence of resistance.

Decreased efficiency of trypsinization of cells following photodynamic therapy:evaluation of a role for tissue transglutaminase

Identifying the cellular responses to photodynamic therapy (PDT) is important if the mechanisms of cellular damage are to be fully understood. The relationship between sensitizer, fluence rate and the removal of cells by trypsinization was studied using the RIF-1 cell line. Following treatment of RIF-1 cells with pyridinium zinc (II) phthalocyanine (PPC), or polyhaematoporphyrin at 10 mW cm−2 (3 J cm−2), there was a significant number of cells that were not removed by trypsin incubation compared to controls. Decreasing the fluence rate from 10 to 2.5 mW cm−2 resulted in a two-fold increase in the number of cells attached to the substratum when PPC used as sensitizer; however, with 5,10,15,20 meso-tetra(hydroxyphenyl) chlorin (m-THPC) there was no resistance to trypsinization following treatment at either fluence rate. The results indicate that resistance of cells to trypsinization following PDT is likely to be both sensitizer and fluence rate dependent. Increased activity of the enzyme tissue-transglutaminase (tTGase) was observed following PPC-PDT, but not following m-THPC-PDT. Similar results were obtained using HT29 human colonic carcinoma and ECV304 human umbilical vein endothelial cell lines. Hamster fibrosarcoma cell (Met B) clones transfected with human tTGase also exhibited resistance to trypsinization following PPC-mediated photosensitization; however, a similar degree of resistance was observed in PDT-treated control Met B cells suggesting that tTGase activity alone was not involved in this process.

Adaptive resistance to biocides in Salmonella enterica and Escherichia coli O157 and cross-resistance to antimicrobial agents

The mechanisms by which bacteria resist killing by antibiotics and biocides are still poorly defined, although repeated exposure to sublethal concentrations of antibacterial agents undoubtedly contributes to their development. This study aimed both to investigate the potential of Salmonella enterica and Escherichia coli O157 for adaptive resistance to commonly used biocides and to determine any cross-resistance to antibiotics. Strains were repeatedly passaged in media containing increasing concentrations of a biocide or antibiotic until adaptive resistance was obtained. A wide panel of antimicrobial agents was then screened by using the adapted strain to determine cross-resistance, if any. Adaptive resistance was readily achieved for both S. enterica and E. coli O157. Cross-resistance in adaptively resistant S. enterica varied with the serotype; Salmonella enterica serovar Enteritidis expressed cross-resistance to chloramphenicol, whereas Salmonella enterica serovar Typhimurium expressed cross-resistance to chlorhexidine. Benzalkonium chloride-resistant Salmonella enterica serovar Virchow showed elevated resistance to chlorhexidine; however, chlorhexidine-resistant Salmonella serovar Virchow did not demonstrate reciprocal cross-resistance to benzalkonium chloride, suggesting specific rather than generic resistance mechanisms. E. coli O157 strains acquired high levels of resistance to triclosan after only two sublethal exposures and, when adapted, repeatedly demonstrated decreased susceptibilities to various antimicrobial agents, including chloramphenicol, erythromycin, imipenem, tetracycline, and trimethoprim, as well as to a number of biocides. These observations raise concern over the indiscriminate and often inappropriate use of biocides, especially triclosan, in situations where they are unnecessary, whereby they may contribute to the development of microbial resistance mechanisms.