Antibiotikaresistenz und Biofilmbildung bei Erregern der bovinen Mastitis

Die vorliegende Arbeit wurde im Rahmen eines Verbundprojektes durchgeführt, das von der Bundesanstalt für Landwirtschaft und Ernährung (BLE)- gefördert wurde. Ziel dieses Projektes war die Reduktion (multi-) resistenter bakterieller Erreger in der Milchviehhaltung durch den Einsatz antimikrobieller Peptide (AMP). Dazu wurde eine insgesamt 496 Isolate umfassende Stammsammlung Mastitis-assoziierter bakterieller Pathogene etabliert, die für jede der 9 Zielspezies (Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Klebsiel-la pneumoniae, Klebsiella oxytoca, Staphylococcus aureus, Streptococcus agalactiae, Strep-tococcus dysgalactiae und Streptococcus uberis) 50 Isolate beinhalten sollte. Durch diese Vorgehensweise konnten dabei nur bedingt Rückschlüsse auf die Prävalenz der Erregerspezies gezogen werden, da einige Spezies für die vorliegende Arbeit gezielt asserviert wurden. Die besondere Bedeutung von Streptococcus uberis als Erreger der bovinen Mastitis spiegelte sich jedoch in der hohen Isolationsrate wider. Die asservierten Bakterien wurden hinsichtlich ihrer Sensivität gegenüber therapeutisch rele-vanter Antibiotika charakterisiert. Dabei konnten 12 Escherichia coli-Isolate mit einer Resis-tenz gegen verschiedene Cephalosporine (1., 3. und 4. Generation) und sieben Methicillin-resistente Staphylococcus aureus identifiziert werden. Auch hier kann die vorliegende Arbeit keinen Hinweis auf die Prävalenz (multi-) resistenter Erreger liefern, da im Verlauf der Studie gezielt resistente Isolate asserviert wurden. Weiterhin wurden die Biofilm-bildenden Eigenschaften der Mastitis-assoziierten Isolate untersucht. Die klinische Relevanz Biofilm-assoziierter Infektionen liegt unter anderem in der vermittelten erhöhten Resistenz der beteiligten Bakterien gegenüber antibiotischen Medikamenten und, damit verbunden, der schlechteren Prognose sowie einer teils langwierigen und intensiven Therapie. Als Alternative für den schwer zu standardisierenden Kristallviolett-Assay wurde der einfach durchzuführende, hoch reproduzierbare und ressourcenschonende Silicone-Disc-Assay etabliert. Durch die Anzucht der Bakterien auf Silikoncoupons ermöglicht er die Quantifizierung der bakteriellen Biofilme auf einem sowohl in der Milchindustrie als auch in der Human- und Veterinärmedizin relevanten Material. Mit Ausnahme der Vertreter der untersuchten Streptococcus spp. bildeten die getesteten Isolate in vitro einen Biofilm aus, was wertvolle Informationen für die Therapie bakterieller Mastitiden vermittelt. Die höchste ermittelte KbE/Coupon konnte für das Escherichia coli Isolat IMT38014 mit 1,3x10^7 nachgewiesen werden. Die niedrigste KbE wurde für die untersuchten Streptococcus dysgalactiae Isolate mit einer durchschnittlichen KbE/Coupon von 8,0x10^4 bestimmt. AMPs sind in Zeiten der zunehmenden Bedrohung durch multi- oder panresistente bakterielle Infektionserreger eine mögliche Alternative für die Bekämpfung der Pathogene. In diesem Projekt wurden AMPs sowohl in gelöster, als auch in gekoppelter, immobilisierter Form im Hinblick auf ihre Wirksamkeit gegenüber Mastitis-assoziierten Pathogenen getestet. Dabei konnte für Protamin und OH-CATH30 die höchste Wirksamkeit nachgewiesen werden. Die Kopplung der AMPs erfolgte auf Silikon und führte im Experiment zu einer Reduktion der Keimlast um bis zu zwei log-Stufen. Nach dreistündiger Inkubation der Escherichia coli IMT37453 konnte auf der unbeschichteten Kontrolloberfläche eine KbE von 4,7x10^7 be-stimmt werden. Die Kopplung von BMAP-27 reduzierte die Keimlast auf 5,8x10^5 und die Kopplung von OH-CATH30 auf 1,7x10^5. Durch Optimierungen des Kopplungsprozesses und den Einsatz zusätzlicher AMPs, auch in Kombinationen, könnte die antimikrobielle Aktivität der Oberflächen weiter gesteigert werden. Aufgrund des flexibel und vielseitig eingesetzten Materials Silikon könnte die Anwendung der antimikrobiellen Oberflächen auf verschiedene Bereiche der Veterinärmedizin, der Humanmedizin und weitere Gebiete übertragen werden

Populism and the evangelical church in Latin America: how anti-LGBTI forces tried to stop the Colombian peace agreement

The present paper explores the relationship between right-wing populism and the neo-Pentecostal Evangelical churches in Latin America, focusing on the anti-LGBT discourse emanating from this relationship. It argues that right-wing populists have been antagonizing the “people” against an imaginary LGBTI foe and using religious jargon and support to mobilize the masses against gender identity and sexual orientation achievements in the region. This argument is illustrated by a case study on one of the most emblematic moments of anti-LGBTI rhetoric in the last decade: the 2016 peace agreement referendum in Colombia. After more than fifty years of war between the FARC-EP and the government, a religious-populist movement claimed the Colombian peace agreement was tainted by “gender ideology”, which would threaten Colombian traditions and institutions. The 2016 referendum became a platform for advancing and repudiating LGBTI rights, and the subsequent rejection of the Colombian peace agreement is a case in point of the sharp opposition and "us vs them" narrative of right-populists and the neo-Pentecostal church against the LGBTI agenda

Dois pesos, duas medidas: a aplicação da necessidade e da proporcionalidade no jus ad bellum

RESUMOEstabelecido no artigo 51 da Carta das Nações Unidas, o direito à legítima defesa não é absoluto, devendo o Estado-vítima de ataque armado respeitar os requisitos pré-determinados pela estrutura legal internacional. Os princípios da necessidade e proporcionalidade da defesa exercem função primordial nesse sentido, uma vez que, segundo o direito costumeiro internacional, o Estado deve conformar sua conduta a eles. O presente trabalho tem por objetivo estabelecer o atual estado da arte no que respeita à necessidade e à proporcionalidade, como limitadoras do direito à legítima defesa no direito internacional público. Os mencionados princípios, apesar de bem consolidados e de fazerem parte do direito consuetudinário internacional, não têm seus contornos bem delimitados, causando discordâncias entre a prática estatal e a doutrina. PALAVRAS-CHAVEDireito internacional público. Legítima defesa. Necessidade. Proporcionalidade. ABSTRACTThe right to self-defense, established in the article 51 of the Charter of the United Nations, is not absolute, and the State victimized by an armed attack must comply with the requirements determined by the international legal framework. In this sense, the principles of necessity and proportionality of the defense play a primary role since, according to customary international law, the State must shape its conduct to these principles. The present work aims to outline the current state of the art of necessity and proportionality as limits to the right to self-defense in public international law. These principles, although well-established and part of international customary law, do not have their boundaries well-defined, causing disagreements between State practices and doctrine. KEYWORDSPublic international law. Self-defense. Necessity. Proportionality

Necessidade e proporcionalidade : requisitos para legítima defesa no direito internacional

Estabelecido no artigo 51 da Carta das Nações Unidas, o direito à legítima defesa não é absoluto, devendo o Estado-vítima de ataque armado respeitar os requisitos pré-determinados pela estrutura legal internacional. Os princípios da necessidade e proporcionalidade da defesa exercem função primordial nesse sentido, uma vez que, segundo o direito costumeiro internacional, o Estado deve conformar sua conduta a esses princípios. O presente trabalho tem por objetivo estabelecer o atual estado da arte da necessidade e da proporcionalidade, como limitadoras do direito à legítima defesa no direito internacional público. Os mencionados princípios, apesar de bem consolidados e de fazerem parte do direito consuetudinário internacional, não têm seu contorno bem delimitado, causando discordâncias entre prática estatal e a doutrina. A metodologia utilizada neste trabalho é a revisão de literatura nacional e internacional, análise de prática estatal, além de pesquisa documental e jurisprudencial.The right to self-defense, established in the article 51 of the Charter of the United Nations, is not absolute, and the victim-state of an armed attack must comply with the requirements determined by the international legal framework. In this sense, the principles of necessity and proportionality of the defense play a primary role since, according to customary international law, the State must shape its conduct to these principles. The present work aims to outline the current state of the art of necessity and proportionality, as limiting the right to self-defense in public international law. These principles, although well-established and part of international customary law, do not have their boundaries well defined, causing disagreements between state practice and doctrine. The methodology used in this work is a review of national and international literature, analysis of state practice, as well as documentary and jurisprudential research

Populism and the Evangelical church in Latin America: how anti-LGBTI forces tried to stop the Colombian peace agreement = Populismo e Igreja Evangélica na América Latina: como as forças anti-LGBTI tentaram impedir o acordo de paz colombiano

- DOI: 10.5102/rdi.v17i2.6685Explora a relação entre o populismo de direita e as igrejas evangélicas neopentecostais na América Latina, enfocando o discurso anti-LGBT que emana dessa relação

A Multi-Level View of the Antecedents and Consequences of Trust in Virtual Leaders

Although trust is widely acknowledged as critical to virtual teams, little is known regarding the causes and consequences of trust in leaders of virtual teams. This paper examines the antecedents and consequences of trust in virtual team leaders. Using survey and archival data from a massively multiplayer online game (MMOG), this study’s findings show that trust in the leader is affected by team members’ use of synchronous communication and breadth of communication with leaders as well as team members’ distance from each other. Furthermore, reasoning that team size and culture create a shared context qualifying team members’ experiences, we found that team size and collectivistic values diminished the benefits of synchronous communication and breadth of communication, respectively. The findings also revealed that trust in leaders had a positive relationship to team performance. Detailed discussion of the findings is provided in the conclusion of the paper

MMOGs as Emerging Opportunities for Research on Virtual Organizations and Teams

Massively Multiplayer Online Games (MMOG) offer new promising opportunities to research virtual organizations and teams. The characteristics of MMOGs allow researchers to obtain objective data from a large and multi-national population. Lasting over months or even years, MMOGs facilitate longitudinal studies and ensure a high involvement of participants. Moreover, collecting data from online surveys and game servers keeps the costs of MMOG studies low. In this paper, we illustrate how research in MMOGs can utilize these opportunities to overcome some limitations of traditional research environments. Further we discuss the diverse information and communication technology (ICT) usage in MMOGs and therefore argue that research in MMOGs can provide a glimpse into the future application of ICT in real life organizations

How to survive pig farming: Mechanism of SCCmec element deletion and metabolic stress adaptation in livestock-associated MRSA

Previous research on methicillin susceptible Staphylococcus aureus (MSSA) belonging to livestock-associated (LA-) sequence type (ST) 398, isolated from pigs and their local surroundings, indicated that differences between these MSSA and their methicillin resistant predecessors (MRSA) are often limited to the absence of the staphylococcal cassette chromosome mec (SCCmec) and few single nucleotide polymorphisms. So far, our understanding on how LA-MRSA endure the environmental conditions associated with pig-farming as well as the putative impact of this particular environment on the mobilisation of SCCmec elements is limited. Thus, we performed in-depth genomic and transcriptomic analyses using the LA-MRSA ST398 strain IMT38951 and its methicillin susceptible descendant. We identified a mosaic-structured SCCmec region including a putative replicative SCCmecVc which is absent from the MSSA chromosome through homologous recombination. Based on our data, such events occur between short repetitive sequences identified within and adjacent to two distinct alleles of the large cassette recombinase genes C (ccrC). We further evaluated the global transcriptomic response of MRSA ST398 to particular pig-farm associated conditions, i.e., contact with host proteins (porcine serum) and a high ammonia concentration. Differential expression of global regulators involved in stress response control were identified, i.e., ammonia-induced alternative sigma factor B-depending activation of genes for the alkaline shock protein 23, the heat shock response and the accessory gene regulator (agr)-controlled transcription of virulence factors. Exposure to serum transiently induced the transcription of distinct virulence factor encoding genes. Transcription of genes reported for mediating the loss of methicillin resistance, especially ccrC, was not significantly different compared to the unchallenged controls. We concluded that, from an evolutionary perspective, bacteria may save energy by incidentally dismissing a fully replicative SCCmec element in contrast to the induction of ccr genes on a population scale. Since the genomic SCCmec integration site is a hot-spot of recombination, occasional losses of elements of 16 kb size may restore capacities for the uptake of foreign genetic material. Subsequent spread of resistance, on the other hand, might depend on the autonomous replication machinery of the deleted SCCmec elements that probably enhance chances for reintegration of SCCmec into susceptible genomes by mere multiplication