Photodynamic and Antibiotic Therapy Impair the Pathogenesis of Enterococcus faecium in a Whole Animal Insect Model

Enterococcus faecium has emerged as one of the most important pathogens in healthcare-associated infections worldwide due to its intrinsic and acquired resistance to many antibiotics, including vancomycin. Antimicrobial photodynamic therapy (aPDT) is an alternative therapeutic platform that is currently under investigation for the control and treatment of infections. PDT is based on the use of photoactive dye molecules, widely known as photosensitizer (PS). PS, upon irradiation with visible light, produces reactive oxygen species that can destroy lipids and proteins causing cell death. We employed Galleria mellonella (the greater wax moth) caterpillar fatally infected with E. faecium to develop an invertebrate host model system that can be used to study the antimicrobial PDT (alone or combined with antibiotics). In the establishment of infection by E. faecium in G. mellonella, we found that the G. mellonella death rate was dependent on the number of bacterial cells injected into the insect hemocoel and all E. faecium strains tested were capable of infecting and killing G. mellonella. Antibiotic treatment with ampicillin, gentamicin or the combination of ampicillin and gentamicin prolonged caterpillar survival infected by E. faecium (P = 0.0003, P = 0.0001 and P = 0.0001, respectively). In the study of antimicrobial PDT, we verified that methylene blue (MB) injected into the insect followed by whole body illumination prolonged the caterpillar survival (P = 0.0192). Interestingly, combination therapy of larvae infected with vancomycin-resistant E. faecium, with antimicrobial PDT followed by vancomycin, significantly prolonged the survival of the caterpillars when compared to either antimicrobial PDT (P = 0.0095) or vancomycin treatment alone (P = 0.0025), suggesting that the aPDT made the vancomycin resistant E. faecium strain more susceptible to vancomycin action. In summary, G. mellonella provides an invertebrate model host to study the antimicrobial PDT and to explore combinatorial aPDT-based treatments

Drivers of risk perceptions about the invasive non-native plant Japanese knotweed in domestic gardens

This is the final version of the article. Available from Springer Verlag via the DOI in this record.How people perceive risks posed by invasive non-native plants (INNP) can influence attitudes and consequently likely influence behavioural decisions. Although some drivers of risk perception for INNP have been identified, research has not determined those for INNP in domestic gardens. This is concerning as domestic gardens are where people most commonly encounter INNP, and where impacts can be particularly acute. Using a survey approach, this study determined the drivers of perceptions of risk of INNP in domestic gardens and which risks most concern people. Japanese knotweed Fallopia japonica, in Cornwall, UK, where it is a problematic INNP in domestic gardens, was used as a case study. Possible drivers of risk were chosen a priori based on variables previously found to be important for environmental risks. Participants perceived Japanese knotweed to be less frequent on domestic property in Cornwall if their occupation involved the housing market, if they had not had Japanese knotweed in their own garden, if they did not know of Japanese knotweed within 5 km of their home, or if they were educated to degree level. Participants who thought that the consequences of Japanese knotweed being present on domestic property could be more severe had occupations that involved the housing market, knew of Japanese knotweed within 5 km of their home, or were older. Although concern about the damage Japanese knotweed could do to the structure of a property was reported as the second highest motivation to control it by the majority of participants, the perception of threat from this risk was rated as relatively low. The results of this study have implications for policy, risk communication, and garden management decisions. For example, there is a need for policy that provides support and resources for people to manage INNP in their local area. To reduce the impact and spread of INNP we highlight the need for clear and accurate risk communication within discourse about this issue. The drivers identified in this study could be used to target awareness campaigns to limit the development of over- or under-inflated risk perceptions.This project was funded as part of the Wildlife Research Co-Operative between the University of Exeter and the Animal and Plant Health Agency

Dilemmas of divorce: How secessionist identities cut both ways

Secessionist groups, if they are to achieve their goal of independence, require both domestic and international support, although neither is easy to obtain. One strategy that such groups may pursue is the use of their identity to gain support both at home and abroad. What causes leaders of a secessionist movement to focus on one identity over another and why do these identities change over time? How much flexibility do elites have in making these choices? This article explores the ways in which latent identities simultaneously constrain and empower secessionist groups in achieving their political ambitions. We argue that the leaders of such groups engage in 'dentity layering' to achieve statehood for their region. Two cases, the Eritrean and Macedonian secessionist movements, are used to illustrate both the logic of identity layering and the dilemmas it entails. The central argument is that the configuration of constraints in each case largely determines the identities that are selected and layered onto the group in question. The use of such identities may also generate resistance - from within the secessionist entity or from outside - which in turn creates incentives for identity change. This analysis shows, first, that territorial identities (as opposed to ethnic or ideological ones) tend to serve as the group's primary mobilizational base, and second, that domestic imperatives weigh more heavily than international pressures in determining the success of these choices. Copyrigh