Sensible, inclusive regulation of pastoralism that has mitigated tension in parts of the Sahel should be extended to the Democratic Republic of Congo (DRC) and the Central African Republic (CAR), where conflicts have worsened with the southward expansion of pastoralism.

Die Zentralafrikanische Republik trägt einen nüchternen, doch gerade in jüngster Zeit allzu treffenden Namen. Denn sie scheint tatsächlich zum Zentrum oder zumindest zum Ballungsraum all der vielfältigen Probleme geworden zu sein, unter denen der Kontinent seit langem leidet und von denen sich aber mittlerweile viele afrikanische Länder befreien können. Da sind die Konflikte um den Abbau wertvoller Ressourcen, besonders von Diamanten. Aus einer kleinen Elite ist eine Reihe unfähiger politischer Führer hervorgegangen. Es mehren sich Konflikte zwischen nomadischen Stämmen und der sesshaften Bevölkerung, was Ursachen auch im Klimawandel hat, und zu neuen Konkurrenzen zwischen den beiden Bevölkerungsteilen führt. Aus Rivalitäten zwischen ethnischen Gemeinschaften erwuchsen blutige Kämpfe und neue Feindschaften: die altbekannte, berüchtigte Kombination von historischen Altlasten und politischem Opportunismus schuf Konflikte auf der Grundlage religiöser Gruppenzugehörigkeit, wie jetzt zwischen Christen und Muslimen. Die schwierige Lage hat dem Land international eine erhöhte, aber nicht immer nützliche Aufmerksamkeit verschafft: des Nachbarlands Tschad, der Zentralafrikanischen Wirtschaftsgemeinschaft, von der Afrikanischen Union und von den Vereinten Nationen. Außerdem von multilateralen und Nicht­regierungs­organisationen, von der ehemaligen Kolonialmacht Frankreich und von weiteren internationalen Akteuren wie den Vereinigten Staaten, Südafrika, der Europäischen Union und unlängst auch von Deutschland. In kürzester Zeit ist die Zentralafrikanische Republik zu trauriger Berühmtheit gelangt. Doch so stark die Aufmerksamkeit auch gestiegen ist, so viel Wissen ist über dieses Land nachzuholen – Wissen, das man braucht, um vernünftig zu handeln. Mein Kollege Thibaud Lesueur und ich haben in den vergangenen drei Jahren viele Monate in der Zen­tralafrikanischen Republik verbracht. Wir konnten vor Ort beobachten, wie der Staat erst allmählich, dann rasant auseinanderfiel. Wir verfolgten, wie ein französisches Expeditionskorps, die Operation Sangaris, den afrikanischen Truppen zu Hilfe kam, um noch eine Spur von Ordnung vor dem drohenden Chaos zu retten, wie es nur eine gut ausgestattete Berufsarmee kann. Wir sahen, wie aus der einst stabilen Bevölkerung eine Generation plündernder Krieger hervorging. Und wir erlebten, wie aus Bangui, der Hauptstadt am Ubangi Fluss mit 750 000 Einwohnern, ein Schauplatz von Lynchjustiz wurde, was 90 Prozent der muslimischen Bevölkerung in die Flucht trieb. Ein Opfer dieser Selbstjustiz wurde auch Jean-Emmanuel Ndjaroua, ein Mitglied des nationalen Übergangsrats. Er machte im Februar den verhängnisvollen Fehler, öffentlich zu Toleranz und Frieden aufzurufen, und wurde auf offener Straße erschossen. Die große Herausforderung besteht nun darin zu verhindern, dass aus Tausenden viele Zehntausende Tote werden. Noch besteht Hoffnung, dass ein solches Blutvergießen vermieden werden kann. Die neue Regierung unter Präsidentin Catherine Samba-Panza hat Potenzial, und die von der Zentralafrikanischen Wirtschaftsgemeinschaft zügig entsandten – aber zu schwachen – Truppen hat man durch eine hoffentlich zielgerichtetere Mission unter Führung der ­Afrikanischen Union ersetzt. Unter der Federführung Frankreichs hat der UN-Sicherheitsrat am 10. April eine Resolution zum Einsatz einer neuen UN-Friedensmission beschlossen. Diese sieht vor, dass die Truppen der Afrikanischen Union im September 2014 unter das Kommando der Vereinten Nationen gestellt werden und die Zahl der internationalen Friedenssoldaten nahezu verdoppelt wird. Die Europäische Union hat derweil für Mai die Stationierung einer „Überbrückungsmission“ angekündigt. Diese Einsatzverpflichtungen sind mehr als bloße Versprechen, aber sie bleiben dennoch hinter dem zurück, was man als entschiedenes Handeln bezeichnen würde. Was also ist zu tun? Vertrauen zwischen den Religionen Es ist entscheidend, zwischen den Bevölkerungsteilen wieder Vertrauen aufzubauen. Der Imam, der Erzbischof und Vertreter der anderen christlichen Kirchen in Bangui arbeiten bereits eng zusammen, aber ihre Anstrengungen sind bisher auf die Hauptstadt begrenzt – aus der fast alle Muslime geflohen sind. Ein interkonfessioneller Dialog und eine Versöhnungskampagne müssen an der Basis beginnen und mithilfe der Übergangsregierung und ihrer internationalen Unterstützer auf die Provinzen ausgeweitet werden. Die Bausteine dafür existieren bereits – im Westen des Landes beispielsweise sind die verbliebenen muslimischen Flüchtlinge mehrheitlich bei christlichen Missionen untergekommen. Erinnern wir uns: Religiöse Gruppenzugehörigkeiten sind noch nicht lange eine Konfliktursache in der Zentralafrikanischen Republik. Zwei frühere Präsidenten, Bokassa und Patassé, konvertierten zum Islam, und diverse ethnische Gruppen setzen sich aus Christen und Muslimen zusammen. Bis heute sind im vorwiegend muslimischen nordöstlichen Distrikt, in dem sich auch viele aus Bangui vertriebene Krieger aufhalten, die Christen des Saraa-Stammes (zu dem auch viele Muslime gehören) nicht angegriffen worden, und auch nicht das zahlenmäßig große christliche Volk der Banda in Bria. In Bangui entstand als Reaktion auf die Morde eine Nichtregierungsorganisation, Les Frères Centrafricains, die über Aufkleber an Taxis zur Versöhnung aufrief. Junge Christen taten sich zusammen, um gemeinsam Moscheen vor Angriffen zu beschützen. Ankurbelung der Wirtschaft Die Wirtschaft des Landes muss neu belebt werden. Die wichtigsten Exportgüter des Landes sind Holz und Diamanten – und der Handel mit diesen Gütern setzt Sicherheit voraus. Von den fünf privaten Firmen, die bislang die Holzindustrie dominierten, arbeiten nur noch zwei. Ein Angestellter vor Ort erzählte uns, wie sein Betrieb zuerst Anfang 2013 von der Präsidentengarde durchsucht wurde, daraufhin von den muslimisch dominierten Séléka-Rebellen und schließlich von der prochristlichen Anti-Balaka-Bewegung, und wie alle von ihnen Fahrzeuge stahlen. Der Diamantenhandel ist ebenfalls in eine schwere Schieflage geraten, denn die Händler waren fast ausschließlich Muslime. Mit Beginn des Gegenaufstands der Anti-Balaka-Milizen flohen sie aus den Städten, ihre Geschäfte wurden geplündert. Auf lange Sicht muss der Staat seine Kontrolle über die Diamantenfelder wiederherstellen und für die Sicherheit der Händler sowie die Transparenz der Handelswege sorgen. Dazu müssen Zivilbeamte und Polizei eingesetzt werden. Zum jetzigen Zeitpunkt können allein Friedenstruppen dafür sorgen, dass der Handel wieder sicher aufgenommen werden kann. Der bedeutendste nicht exportorientierte Wirtschaftszweig des Landes ist die landwirtschaftliche Selbstversorgung. Auch sie leidet unter der problematischen Sicherheitslage, besonders dort, wo Nomaden und Farmer in Konkurrenz um Land aufeinandertreffen. Die Wanderungen der nomadischen Hirten aus dem Tschad im Norden in die Zentralafrikanische Republik müssen dringend unter eine von allen Seiten ausgehandelte Regelung gestellt werden, von der Art, wie sie in Niger und Tschad bereits erfolgreich ist. In den größeren Städten des Landes muss indessen Arbeit für die ­dortigen Kämpfer geschaffen werden. In der Hauptstadt Bangui herrscht Gewalt. Dort wird neben einer verbesserten Sicherheitslage dringend mehr Beschäftigung für die Jugendlichen gebraucht, damit diese eine Alternative zu den Milizen finden, die ihnen bisher „Arbeit“ verschafft haben. Die Hauptstadt und weitere Landesteile leiden unter infrastrukturellen Problemen, die durch beschäftigungsintensive Maßnahmen zu lösen wären, für die ungelernte und angelernte Arbeitskräfte eingesetzt werden können. Sicherheit Um die Sicherheit im Land wiederherzustellen, muss die Afrikanische Union mit den Vereinten Nationen zusammenarbeiten. Die neue UN-­Resolution will aus den 6000 AU-Soldaten UN-Blauhelme machen, aber Streit um Zuständigkeiten könnte die Umsetzung erschweren. Auch Frankreich und die Europäische Union müssen eine Grundlage zur Zusammenarbeit finden. Hier wird vermutlich Deutschland eine Schlüsselrolle spielen. Die deutsche Koalitionsregierung hat den Versuch gestartet, die deutsch-französische ­Zusammenarbeit neu zu beleben, gerade auf außenpolitischem Gebiet. Im April sprach Bundeskanzlerin Angela Merkel von Frankreich und Deutschland als „Motor“ der Beziehungen zwischen der EU und Afrika, und Frankreichs Staatspräsident François Hollande unterstrich die „besondere Freundschaft“ beider Länder. Deutschland hat sich in bisher nicht gekannter Weise verpflichtet, in Mali und der Zentralafrikanischen Republik militärische Hilfen bereitzustellen – dies soll jeweils in enger Abstimmung mit Frankreich geschehen. Hinzu kommt eine bedeutsame entwicklungspolitische Unterstützung. Diese französisch-deutsche Führung hat aus einem vagen Plan ein handfestes Unternehmen gemacht; mittlerweile haben sich Estland, Finnland, Frankreich, Deutschland, Italien, Lettland, Litauen, Luxemburg, Polen, Portugal, Schweden, Spanien, Großbritannien sowie Georgien zur Mission bekannt. Der Großteil der Truppen wird von Estland, Frankreich, Georgien, Polen und Spanien gestellt. Deutschland legt seinen Schwerpunkt auf den strategischen Lufttransport, Großbritannien kümmert sich um logistische Fragen und Italien um die Technik. Selbst wenn die EU-Überbrückungsmission Realität wird und sich die Beziehungen zur Afrikanischen Union verbessern, wird es für den ­Sicherheitsrat der Vereinten Nationen und die UN-Organisationen sehr schwierig werden, erfolgreich eine Blauhelmtruppe in der Zentralafrikanischen Republik zu etablieren. Die Vereinten Nationen müssen die Frage beantworten, welche ihrer Mitgliedstaaten die Truppen stellen. Dabei sollten sie Tschad außen vor lassen. Das Land ist schon zu sehr in die Angelegenheiten der Zentralafrikanischen Republik verstrickt und hat seine Friedensmission Anfang April aufgekündigt, nachdem tschadische Soldaten beschuldigt wurden, für den Tod von Zivilisten verantwortlich zu sein. Die Befehlsgewalt über die Truppen wird zwar formal im September von der AU auf die UN übergehen. Aber praktisch wird die UN-Mission wahrscheinlich nicht vor Ende des Jahres in vollem Umfang anlaufen. Dabei erfordert die Entwaffnung der Milizen schnelles Handeln: Die verbliebene muslimische Bevölkerung in Bangui hat sich in der PK5 genannten muslimischen Enklave bewaffnet, und auch die Anti-Balaka-Milizen haben bisher keine Probleme, in der Hauptstadt an Waffen zu kommen – obwohl Tausende französische und afrikanische Friedenssoldaten durch die Straßen der Hauptstadt patrouillieren. Der muslimische Bürgermeister von Banguis drittem Bezirk, zu dem auch PK5 gehört, sagte im März: „Wenn wir PK5 verlassen, um in ein benachbartes Gebiet zu gehen, werden wir noch am gleichen Tag getötet.“ Die Franzosen verpassten im Dezember und Januar die Gelegenheit zur weitgehenden Entwaffnung der Séléka-Truppen, als diese noch in vier Lagern festgehalten wurden. Eine UN-Mission wird es mit der Entwaffnung nicht leichter haben als die Franzosen. Der Plan der Vereinten Nationen sieht vor, dass zuerst Soldaten stationiert werden, dann eine funktionierende Polizei aufgebaut wird, und dann ein Justizsystem. Die größten Schwachstellen sind die Soldaten und Geld: Von beiden gibt es viel zu wenig. Ein strategischer Fahrplan Die Übergangsregierung der Zentralafrikanischen Republik wie auch die internationale Gemeinschaft brauchen dringend einen Plan. Auf nationaler Ebene hatte es Ende vergangenen Jahres einen gegeben – einen mangelhaften, aber immerhin etwas. Die neue Regierung unter Catherine Samba-Panza ist die dritte Regierung innerhalb eines Jahres, aber sie ist vielversprechend. Die meisten wichtigen Ministerien sind mit Technokraten statt mit Parteigenossen besetzt. Präsidentin Samba-Panza hat bereits zu Beginn ihrer Amtszeit die Bedeutung von Justiz und Versöhnung betont. In einem Gespräch im April mit Crisis-Group-Präsidentin Louise Arbour bestätigte sie dies und unterstrich, dass ihr Land auf die Hilfe ausländischer Richter angewiesen sei, um ein effektives Justizsystem aufzubauen. All dies gibt Anlass zur Hoffnung. Was man jedoch für die erweiterte internationale Intervention braucht, sind eine kohärente Führung, strategisches Denken sowie einen gemeinsamen Stabilisierungsplan, der es der Übergangsregierung ermöglicht, mittel- und langfristige Prioritäten zu setzen. Die internationale Kontaktgruppe sowie der jüngste Bericht des UN-Generalsekretärs betonen zu Recht, wie wichtig es ist, die Sicherheit im Land wiederherzustellen, die staatlichen Dienste zu reaktivieren und Wahlen vorzubereiten. Aber sie gehen nicht auf die tieferliegenden Probleme ein, insbesondere nicht auf den wirtschaftlichen Niedergang, der die Hauptursache für den Staatszerfall ist. Jemand – beispielsweise die EU oder Mitglieder der internationalen Kontaktgruppe – sollte dafür sorgen, dass die bisherigen Entwicklungs- und Aufbauprogramme überprüft werden. Eine solche Überprüfung ist aus zwei Gründen wichtig: erstens um zu verstehen, was bei der Reform des Sicherheitssektors, bei der Entwaffnung und Demobilisierung von Kämpfern sowie den Reintegrationsmaßnahmen schiefgelaufen ist. Und zweitens, um eine Stabilisierungsstrategie zu entwerfen, die die Wirtschaft in den Mittelpunkt stellt und das bietet, was zurzeit fehlt: neue Ideen für alte Probleme sowie eine langfristige Roadmap für die nationalen und internationalen Akteure. Auf diese Weise hätte man eine Grundlage für die angedachte Geberkonferenz im späteren Jahresverlauf und es wäre einfacher, eine sinnvolle Aufgabenverteilung unter den internationalen Akteuren zu verabreden. Ein solcher Rahmen ist unverzichtbar, um der neuen Regierung ein Fundament für ihre Herkulesaufgabe zu geben, nämlich aus dem Land wieder einen funktionierenden Staat zu machen und die Wirtschaft wieder aufzubauen, die Grundlage eines jeden zukunftsfähigen Staates. Bei dieser Überprüfung sollte man keine Zeit verlieren. Denn wie schon in der Vergangenheit könnte das ­Interesse der in­ternationalen Gemeinschaft an der Zentralafrikanischen Republik wieder schwinden. Gerade dies war in der Vergangenheit ein Hauptgrund dafür, dass sich die Probleme des Landes so häufig wiederholten. Geschieht das nicht, könnte es passieren, dass die geplante Überbrückungsmission schon in einem Jahr nur noch eine vage Erinnerung ist, dass der Fall Zentralafrikanische Republik Frankreich aufgebürdet wird, dass die afrikanischen Staaten gerade genug Mittel haben, um einzuschreiten, aber zu wenig, um irgendetwas langfristig zu stabilisieren, und dass die Übergangsregierung dann nur noch damit beschäftigt ist, die Fassade eines Staates aufrechtzuerhalten.

The United Nations Security Council decided on 10 April to deploy a peacekeeping mission in the Central African Republic (CAR) which will take over the mission of the African Union (MISCA), which itself succeeded the mission of the Economic Community of Central African States (MICOPAX).

To stabilise the Central African Republic (CAR), the transitional government and its international partners need to prioritise, alongside security, action to fight corruption and trafficking of natural resources, as well as revive the economy.

Cameroon’s apparent stability belies the variety of internal and external pressures threatening the country’s future. Without social and political change, a weakened Cameroon could become another flashpoint in the region.

A new consensus and strategy are urgently needed to tackle the numerous, brutal armed groups in eastern Congo and to save the February 2013 Peace, Security and Cooperation Framework (PSCF) in the Great Lakes region.

The ever-decreasing likelihood of a free and fair presidential election is in growing conflict with a popular desire for change in Burundi. To safeguard the Arusha principles agreed in 2000 to end Burundi’s civil war, the opposition and President Nkurunziza in particular must return to the path of democracy and dialogue.

Alors qu’une tentative de coup d’Etat contre Pierre Nkurunziza, émanant de l’ex-chef d’état-major, Godefroid Niyombaré, est en cours au Burundi, Thierry Vircoulon chercheur à l'International Crisis Group, explique qui est le général putschiste et analyse, plus généralement, l'appareil sécuritaire du Burundi.

La imagen de Camerún como una isla de paz en medio de una región tumultuosa terminó en 2013, cuando la violencia de Boko Haram cruzó la frontera nigeriana. Este grupo está afiliado al llamado Estado Islámico o Daesh, e incluso se rebautizó como Estado Islámico de África Occidental a principios de este año. Pero la forma brutal de yihadismo africano que representa difícilmente se explica por el auge del Estado Islámico en Irak y Siria. De hecho, es en parte una consecuencia del cambiante panorama religioso africano, que afecta y no poco a Camerún.

The image of Cameroon as an island of peace amidst regional turmoil ended in 2013, when Boko Haram’s violence first crossed the Nigerian border. The militant group is affiliated with so-called Islamic State or Daesh, and even renamed itself Islamic State in West Africa earlier this year. But the brutal form of African jihadism it represents is hardly a result of the Islamic State’s rise in Iraq and Syria. In fact, it is in part a consequence of Africa’s changing religious landscape – not least in Cameroon.

L’image de havre de paix dans une région en proie aux conflits dont bénéficiait le Cameroun a volé en éclats depuis l’irruption de Boko Haram en 2013 au nord du pays. Ce mouvement, devenu l’Etat islamique en Afrique de l’Ouest en mars 2015, revendique son affiliation à Daech. Néanmoins, l’apparition brutale et sanglante de ce djihadisme africain est moins liée à l’essor de Daech en Irak et en Syrie qu’aux bouleversements du paysage religieux de l’Afrique en général et du Cameroun en particulier.

In Central African Republic, the conflict between armed groups is now compounded by a conflict between armed communities. The roadmap to end the crisis including elections late 2015 presents only a short-term answer and risks exacerbating existing tensions. The transitional authorities and their international partners must address crucial issues by implementing a comprehensive disarmament policy and reaffirming that Muslims belong within the nation.

En Centrafrique, la course aux élections qui prévoit des scrutins présidentiel et législatif avant la fin de l’année est aussi irréaliste que dangereuse. Alors que le plan initial de la transition a complètement déraillé, l’obstination des internationaux, et plus particulièrement de la France, à faire voter les Centrafricains à l’ombre des groupes armés, avec une administration territoriale squelettique et des haines inter-communautaires tenaces ressemble plus à une fuite en avant qu’à un processus de transition accompli.

Ahead of Chad’s presidential election on 10 April popular discontent is rising amid a major economic crisis, growing intra-religious tensions and deadly Boko Haram attacks. The regime that portrays itself as spearheading the fight against regional jihadism could see all sorts of violent actors gain influence at home if it pursues exclusionary politics and denies its people a viable social contract.

Texas has become the first state to have its "alternate assessment aligned to modified academic-achievement standards" pass the U.S. Department of Education's peer-review process.

A 10-year study by a blue-ribbon panel of scientists concludes that high-stakes testing and other accountability measures have largely failed to translate to real improvements in student achievement.

A 10-year study by a blue-ribbon panel of scientists concludes that high-stakes testing and other accountability measures have largely failed to translate to real improvements in student achievement.

Mostly, states are holding to a higher bar for student achievement than they did a decade ago. But Iowa, Texas, and Virginia continue to show large gaps between their state proficiency standards and NAEP's.

The Education Week Research Center looks at student scores on the National Assessment of Educational Progress from 2003 to 2015, a period overlapping with the No Child Left Behind Act.

More than four years after the passage of ESSA, English-language-learner education policies across the country remain "disjointed and inaccessible," a new report concludes.

The U.S. tests its students more than most nations, but is the deluge of data providing the information schools need?

Helen Janc Malone introduces this week's blog theme, "accountability and assessment systems." She writes that at the heart of the current accountability debate is a fundamental question, What is the purpose of all the collected assessment data? Are they an end game or a starting point to educational

If we continue to focus on student growth and improvement as learners, keep track of that progress, and watch its impact on standard test results, will we be able to know if what we are doing is helping students develop as learners and thinkers.

This article, published ahead of print on 28 July 2008, has been withdrawn by the authors. Although moderate synergy between P2-RANTES and C peptides can be observed with high statistical significance in cell fusion assays, this synergy was not able to be verified in HIV viral assays. The authors regret the overstatement of synergy and will revise the paper for publication at a later date.

Background: This study summarizes drug resistance analyses in 4 recent phase 2b trials of the respiratory syncytial virus (RSV) fusion inhibitor presatovir in naturally infected adults.

Methods: Adult hematopoietic cell transplant (HCT) recipients, lung transplant recipients, or hospitalized patients with naturally acquired, laboratory-confirmed RSV infection were enrolled in 4 randomized, double-blind, placebo-controlled studies with study-specific presatovir dosing. Full-length RSV F sequences amplified from nasal swabs obtained at baseline and postbaseline were analyzed by population sequencing. Substitutions at RSV fusion inhibitor resistance-associated positions are reported.

Results: Genotypic analyses were performed on 233 presatovir-treated and 149 placebo-treated subjects. RSV F variant V127A was present in 8 subjects at baseline. Population sequencing detected treatment-emergent substitutions in 10/89 (11.2%) HCT recipients with upper and 6/29 (20.7%) with lower respiratory tract infection, 1/35 (2.9%) lung transplant recipients, and 1/80 (1.3%) hospitalized patients treated with presatovir; placebo-treated subjects had no emergent resistance-associated substitutions. Subjects with substitutions at resistance-associated positions had smaller decreases in viral load during treatment relative to those without, but similar clinical outcomes.

Conclusions: Subject population type and dosing regimen may have influenced RSV resistance development during presatovir treatment. Subjects with vs without genotypic resistance development had decreased virologic responses but comparable clinical outcomes.

Leishmania major is the causative agent of cutaneous leishmaniasis (CL). No human vaccine is available for CL and current drug regimens present several drawbacks such as emerging resistance, severe toxicity, medium effectiveness, and/or high cost. Thus, the need for better treatment options against CL is a priority. In the present study, we validate the enzyme methionine aminopeptidase-1 (MetAP1), a metalloprotease that catalyzes the removal of N-terminal methionine from peptides and proteins, as a chemotherapeutic target against CL infection. The in vitro antileishmanial activity of eight novel MetAP1 inhibitors (OJT001-OJT008) were investigated. Three compounds OJT006, OJT007, and OJT008 demonstrated potent anti-proliferative effect in macrophages infected with L. major amastigotes and promastigotes at submicromolar concentrations, with no cytotoxicity against host cells. Importantly, the leishmanicidal effect was diminished by almost 10-fold in transgenic L. major promastigotes overexpressing MetAP1_LM in comparison to wild-type promastigotes. Furthermore, the in vivo activity of OJT006, OJT007, and OJT008 were investigated in L. major-infected BALB/c mice. In comparison to the control group, OJT008 significantly decreased footpad parasite load by 86%, and exhibited no toxicity against in treated mice. We propose MetAP1 inhibitor OJT008 as a potential chemotherapeutic candidate against CL infection caused by L. major infection.

Malaria parasites invade and replicate within red blood cells (RBCs), extensively modifying their structure and gaining access to the extracellular environment by placing the plasmodial surface anion channel (PSAC) into the RBC membrane. Expression of members of the cytoadherence linked antigen gene 3 (clag3) family is required for PSAC activity, a process that is regulated epigenetically. PSAC is a well-established route of uptake for large, hydrophilic antimalarial compounds and parasites can acquire resistance by silencing clag3 gene expression, thereby reducing drug uptake. We found that exposure to sub-IC50 concentrations of the histone methyltransferase inhibitor chaetocin caused substantial changes in both clag3 gene expression and RBC permeability, reversing acquired resistance to the antimalarial compound blasticidin S that is transported through PSAC. Chaetocin treatment also altered progression of parasites through their replicative cycle, presumably by changing their ability to modify chromatin appropriately to enable DNA replication. These results indicate that targeting histone modifiers could represent a novel tool for reversing epigenetically acquired drug resistance in P. falciparum.

Continuous spread of antimalarial drug resistance is a threat to current chemotherapy efficacy. Therefore, characterizing the genetic diversity of drug resistance markers is needed to follow treatment effectiveness and further update control strategies. Here, we genotyped Plasmodium falciparum resistance gene markers associated with sulfadoxine-pyrimethamine (SP) and artemisinin-based combination therapy (ACT) in isolates from pregnant women in Ghana. The prevalence of the septuple IRNI-A/FGKGS/T pfdhfr/pfdhps haplotypes including the pfdhps A581G and A613S/T mutations was high at delivery among post-SP treatment isolates (18.2%) compared to those of first-antenatal care (before initiation of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP); 6.1%; p = 0.03). Regarding the pfk13 marker gene, two non-synonymous mutations (N458D and A481C) were detected at positions previously related to artemisinin resistance in isolates from Southeast-Asia. These mutations were predicted in silico to alter the stability of the pfk13 propeller-encoding domain. Overall, these findings highlight the need for intensified monitoring and surveillance on additional mutations associated with increased SP resistance as well as emergence of resistance against artemesinin derivatives.

Lipid II is an essential precursor of the bacterial cell wall biosynthesis and thereby an important target for various antibiotics. Several lanthionine-containing peptide antibiotics target lipid II with lanthionine-stabilized lipid II-binding motifs. Here, we used the biosynthesis system of the lantibiotic nisin to synthesize a two lipid II binding motifs-containing lantibiotic, termed TL19, which contains the N-terminal lipid II binding motif of nisin and the distinct C-terminal lipid II binding motif of one peptide of the two-component haloduracin (i.e. HalA1). Further characterization demonstrated that (i) TL19 exerts 64-fold stronger antimicrobial activity against E. faecium than nisin (1-22), which has only one lipid II binding site, and (ii) both the N- and C-terminal domains are essential for the potent antimicrobial activity of TL19, as evidenced by mutagenesis of each single and double domains. These results show the feasibility of a new approach to synthesize potent lantibiotics with two different lipid II binding motifs to treat specific antibiotic-resistant pathogens.

The quinoline MK-571 is the most commonly used inhibitor of multidrug resistance protein-1 (MRP-1) but was originally developed as a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist. While studying the modulatory effect of MRP-1 on anti-hepatitis C virus (HCV) direct acting-antivirals (DAA) efficiency, we observed an unexpected anti-HCV effect of compound MK-571 alone. This anti-HCV activity was characterized in Huh7.5 cells stably harboring a subgenomic genotype 1b replicon. A dose-dependent decrease of HCV RNA levels was observed upon MK-571 administration, with an EC₅₀ of 9±0.3 μM and a maximum HCV RNA level reduction of approximatively 1 Log₁₀. MK-571 also reduced the replication of the HCV full-length J6/JFH1 model in a dose-dependent manner. However, probenecid and apigenin homodimer (APN), two specific inhibitors of MRP-1, had no effect on HCV replication. In contrast, the CysLTR1 antagonists SR2640 increased HCV-SGR RNA levels in a dose-dependent manner, with a maximum increase of 10-fold. In addition, a combination of natural CysLTR1 agonist (LTD4) or antagonists (zafirlukast, cinalukast, and SR2640) with MK-571 completely reversed its antiviral effect, suggesting its anti-HCV activity is related to CysLTR1 rather to MRP-1 inhibition. In conclusion, we showed that MK-571 inhibits HCV replication in hepatoma cell cultures by acting as a CysLTR1 receptor antagonist, thus unraveling a new host-virus interaction in the HCV life cycle.

Since 2012, single low dose of primaquine (SLDPQ, 0.25mg/kg) has been recommended with artemisinin-based combination therapies, as first-line treatment of acute uncomplicated Plasmodium falciparum malaria, to interrupt its transmission, especially in low transmission settings of multidrug, including artemisinin, resistance. Policy makers in Cambodia have been reluctant to implement this recommendation due to primaquine safety concerns and lack of data on its efficacy.

In this randomized controlled trial, 109 Cambodians with acute uncomplicated P. falciparum malaria received dihydroartemisinin-piperaquine (DP) alone or combined with SLDPQ on the first treatment day. Transmission-blocking efficacy of SLDPQ was evaluated on Days 0, 1, 2, 3, 7, 14, 21, 28 and recrudescence by reverse transcriptase polymerase chain reaction (RT-PCR) (gametocyte prevalence) and membrane-feeding assays with Anopheles minimus mosquitoes (gametocyte infectivity). Without the influence of recrudescent infections, DP+SLDPQ reduced gametocyte carriage 3 fold compared to DP. Of 48 patients tested on Day 0, only three patients were infectious to mosquitoes (~6%). Post-treatment, three patients were infectious: on D14 (3.5%, 1/29), and on the first and seventh day of recrudescence (8.3%, 1/12 for each); this overall low infectivity precluded our ability to assess its transmission blocking efficacy.

Our study confirms effective gametocyte clearance of SLDPQ when combined with DP in multidrug resistant P. falciparum and the negative impact of recrudescent infections due to poor DP efficacy. Artesunate-mefloquine (ASMQ) has replaced DP and ASMQ-SLDPQ has been deployed to treat all P. falciparum symptomatic patients to further support the elimination of multidrug resistant P. falciparum in Cambodia.

Objectives: Antibiotic combination therapy is used for severe infections caused by multidrug-resistant (MDR) Gram-negative bacteria. Yet, data of which combinations are most effective is lacking. This study aimed to evaluate the in vitro efficacy of polymyxin B in combination with 13 other antibiotics against four clinical strains of MDR Pseudomonas aeruginosa.

Methods: We evaluated the interactions of polymyxin B in combination with amikacin, aztreonam, cefepime, chloramphenicol, ciprofloxacin, fosfomycin, meropenem, minocycline, rifampicin, temocillin, thiamphenicol or trimethoprim by automated time-lapse microscopy using predefined cut-off values indicating inhibition of growth (≤10⁶ CFU/mL) at 24 h. Promising combinations were subsequently evaluated in static time-kill experiments.

Results: All strains were intermediate or resistant to polymyxin B, anti-pseudomonal β-lactams, ciprofloxacin and amikacin. Genes encoding β-lactamases (e.g., bla_PAO and bla_OXA-50) and mutations associated with permeability and efflux were detected in all strains. In the time-lapse microscopy experiments, positive interactions were found with 39 of 52 antibiotic combination/bacterial strain setups. Enhanced activity was found against all four strains with polymyxin B used in combination with aztreonam, cefepime, fosfomycin, minocycline, thiamphenicol and trimethoprim. Time kill experiments showed additive or synergistic activity with 27 of the 39 tested polymyxin B combinations, most frequently with aztreonam, cefepime, and meropenem.

Conclusion: Positive interactions were frequently found with the tested combinations, also against strains that harboured several resistance mechanisms to the single drugs and with antibiotics that are normally not active against P. aeruginosa. Further study is needed to explore the clinical utility of these combinations.

β-lactam resistance in Staphylococcus aureus limits treatment options. Stp1 and Stk1, a serine-threonine phosphatase and kinase respectively, mediate serine-threonine kinase (STK) signaling. Loss of function point mutations in stp1 were detected among laboratory passaged, β-lactam resistant S. aureus strains lacking mecA and blaZ, the major determinants of β-lactam resistance in the bacteria. Loss of Stp1 function facilitates β-lactam resistance of the bacteria.

Carbapenems are currently the preferred agents for the treatment of serious Acinetobacter infections. However, whether cefepime/cefpirome can be used to treat Acinetobacter bloodstream infection (BSI) if it is active against the causative pathogens is not clear. This study aimed to compare the efficacy of cefepime/cefpirome and carbapenem monotherapy in patients with Acinetobacter BSI. The population included 360 patients with monomicrobial Acinetobacter BSI receiving appropriate antimicrobial therapy admitted to four medical centres in Taiwan in 2012–2017. The predictors of 30-day mortality were determined by Cox regression analysis. The overall 30-day mortality rate in the appropriate antibiotic treatment group was 25.0% (90/360 patients), respectively. The crude 30-day mortality rates for cefepime/cefpirome and carbapenem therapy were 11.5% (7/61 patients) and 26.3% (21/80 patients), respectively. The patients receiving cefepime/cefpirome/carbapenem therapy were infected by Acinetobacter nosocomialis (51.8%), A. baumannii (18.4%) and A. pittii (12.1%). After adjusting for age, Sequential Organ Failure Assessment (SOFA) score, invasive procedures, and underlying diseases, cefepime/cefpirome therapy was not independently associated with a higher or lower 30-day mortality compared to the carbapenem therapy. SOFA score (hazard ratio [HR], 1.324; 95% confidence interval [CI], 1.137–1.543; P < 0.001) and neutropenia (HR, 7.060; 95% CI, 1.607–31.019; P = 0.010) were independent risk factors for 30-day mortality of patients receiving cefepime/cefpirome or carbapenem monotherapy. The incidence density of 30-day mortality for cefepime/cefpirome versus carbapenem therapy was 0.40% versus 1.04%. The therapeutic response of cefepime/cefpirome therapy was comparable to that of carbapenems among patients with Acinetobacter BSI receiving appropriate antimicrobial therapy.

Carbapenem-resistant Gram-negative pathogens are a critical public health threat and there is an urgent need for new treatments. Carbapenemases (β-lactamases able to inactivate carbapenems) have been identified in both serine β-lactamase (SBL) and metallo β-lactamase (MBL) families. The recent introduction of SBL carbapenemase-inhibitors has provided alternative therapeutic options. Unfortunately, there are no approved inhibitors of MBL-mediated carbapenem-resistance and treatment options for infections caused by MBL-producing Gram-negatives are limited. Here, we present ZN148, a zinc-chelating MBL-inhibitor capable of restoring the bactericidal effect of meropenem and in vitro clinical susceptibility to carbapenems in >98% of a large international collection of MBL-producing clinical Enterobacterales strains (n=234). Moreover, ZN148 was able to potentiate the effect of meropenem against NDM-1-producing Klebsiella pneumoniae in a murine neutropenic peritonitis model. ZN148 showed no inhibition of the human zinc-containing enzyme glyoxylase II at 500 μM and no acute toxicity was observed in an in vivo mouse model with cumulative dosages up to 128 mg/kg. Biochemical analysis showed a time-dependent inhibition of MBLs by ZN148 and removal of zinc ions from the active site. Addition of exogenous zinc after ZN148 exposure only restored MBL activity by ~30%, suggesting an irreversible mechanism of inhibition. Mass-spectrometry and molecular modelling indicated potential oxidation of the active site Cys221 residue. Overall, these results demonstrate the therapeutic potential of a ZN148-carbapenem combination against MBL-producing Gram-negative pathogens and that ZN148 is a highly promising MBL inhibitor, capable of operating in a functional space not presently filled by any clinically approved compound.

Ibrexafungerp (formerly SCY-078) is a semisynthetic triterpenoid and potent (1->3)-β-D-glucan synthase inhibitor. We investigated the in vitro activity, pharmacokinetics, and in vivo efficacy of ibrexafungerp (SCY) alone and in combination with anti-mould triazole isavuconazole (ISA) against invasive pulmonary aspergillosis (IPA). The combination of ibrexafungerp and isavuconazole in in vitro studies resulted in an additive and synergistic interactions against Aspergillus spp. Plasma concentration-time curves of ibrexafungerp were compatible with linear dose proportional profile. In vivo efficacy was studied in a well established persistently neutropenic NZW rabbit model of experimental IPA. Treatment groups included untreated rabbits (UC) and rabbits receiving ibrexafungerp at 2.5(SCY2.5) and 7.5(SCY7.5) mg/kg/day, isavuconazole at 40(ISA40) mg/kg/day, or combinations of SCY2.5+ISA40 and SCY7.5+ISA40. The combination of SCY+ISA produced in vitro synergistic interaction. There was significant in vivo reduction of residual fungal burden, lung weights, and pulmonary infarct scores in SCY2.5+ISA40, SCY7.5+ISA40, and ISA40-treatment groups vs that of SCY2.5-treated, SCY7.5-treated and UC (p<0.01). Rabbits treated with SCY2.5+ISA40 and SCY7.5+ISA40 had prolonged survival in comparison to that of SCY2.5-, SCY7.5-, ISA40-treated or UC (p<0.05). Serum GMI and (1->3)-β-D-glucan levels significantly declined in animals treated with the combination of SCY7.5+ISA40 in comparison to those treated with SCY7.5 or ISA40 (p<0.05). Ibrexafungerp and isavuconazole combination demonstrated prolonged survival, decreased pulmonary injury, reduced residual fungal burden, lower GMI and (1->3)-β-D-glucan levels in comparison to those of single therapy for treatment of IPA. These findings provide an experimental foundation for clinical evaluation of the combination of ibrexafungerp and an anti-mould triazole for treatment of IPA.

Background: Intensive care unit (ICU) patients may experience ceftriaxone underexposure but clinical outcomes data are lacking. The objective of this study was to determine the impact of ceftriaxone dosing on clinical outcomes amongst ICU patients without central nervous system (CNS) infection.

Methods: A retrospective study of ICU patients receiving intravenous, empiric ceftriaxone for non-CNS infections was conducted. Patients ≥18 years of age who received ≤2 grams of ceftriaxone daily for ≥72 hours were included and categorized as receiving ceftriaxone 1 gram or 2 grams daily. The primary, composite outcome was treatment failure: inpatient mortality and/or antibiotic escalation due to clinical worsening. Propensity score matching was performed based on the probability of receiving ceftriaxone 2 grams daily. Multivariable logistic regression determined the association between ceftriaxone dose and treatment failure in a propensity-matched cohort.

Results: A total of 212 patients were included in the propensity-matched cohort. The most common diagnoses (83.0%) were pneumonia and urinary tract infection. Treatment failure occurred in 17.0% and 5.7% of patients receiving 1 gram and 2 grams daily, respectively (p=0.0156). Overall inpatient mortality was 8.5%. Ceftriaxone 2 gram dosing was associated with a reduced likelihood of treatment failure (adjusted odds ratio=0.190; 95% confidence interval: 0.059 – 0.607). Other independent predictors of treatment failure included sequential organ failure assessment score (aOR 1.440, 95% CI 1.254 – 1.653) and creatinine clearance at 72 hours from ceftriaxone initiation (aOR 0.980, 95% CI (0.971 – 0.999).

Conclusions: Ceftriaxone 2 grams daily when used as appropriate antimicrobial coverage may be appropriate for ICU patients with lower mortality risk.

Mucormycosis is a life-threatening infection with high mortality that occurs predominantly in immunocompromised patients. Manogepix (MGX) is a novel antifungal that targets Gwt1, an early step in the conserved glycosylphosphotidyl inositol (GPI) post-translational modification pathway of surface proteins in eukaryotic cells. Inhibition of inositol acylation by MGX results in pleiotropic effects including inhibition of maturation of GPI-anchored proteins necessary for growth and virulence. MGX has been previously shown to have in vitro activity against some strains of Mucorales. Here we assessed the in vivo activity of the prodrug fosmanogepix, currently in clinical development for the treatment of invasive fungal infections, against two Rhizopus arrhizus strains with high (4.0 μg/ml) and low (0.25 μg/ml) minimum effective concentration (MEC) values. In both invasive pulmonary infection models, treatment of mice with 78 mg/kg or 104 mg/kg fosmanogepix, along with 1-aminobenzotriazole to enhance the serum half-live of MGX in mice, significantly increased median survival time and prolonged overall survival by day 21 post infection when compared to placebo. In addition, administration of fosmanogepix resulted in a 1-2 log reduction in both lung and kidney fungal burden. For the 104 mg/kg fosmanogepix dose, tissue clearance and survival were comparable to clinically relevant doses of isavuconazole (ISA), which is FDA approved for the treatment of mucormycosis. These results support continued development of fosmanogepix as a first in class treatment for invasive mucormycosis.

Telacebec (Q203) is a new anti-tubercular drug with extremely potent activity against Mycobacterium ulcerans. Here, we explored the treatment-shortening potential of Q203 alone or in combination with rifampin (RIF) in a mouse footpad infection model. The first study compared Q203 at 5 and 10 mg/kg doses alone and with rifampin. Q203 alone rendered most mouse footpads culture-negative in 2 weeks. Combining Q203 with rifampin resulted in relapse-free cure 24 weeks after completing 2 weeks of treatment, compared to a 25% relapse rate in mice receiving RIF+clarithromycin, the current standard of care, for 4 weeks.

The second study explored the dose-ranging activity of Q203 alone and with RIF, including the extended activity of Q203 after treatment discontinuation. The bactericidal activity of Q203 persisted for ≥ 4 weeks beyond the last dose. All mice receiving just 1 week of Q203 at 2-10 mg/kg were culture-negative 4 weeks after stopping treatment. Mice receiving 2 weeks of Q203 at 0.5, 2 and 10 mg/kg were culture-negative 4 weeks after treatment. RIF did not increase the efficacy of Q203. A pharmacokinetics sub-study revealed that Q203 doses of 2-10 mg/kg in mice produce plasma concentrations similar to those produced by 100-300 mg doses in humans, with no adverse effect of RIF on Q203 concentrations.

These results indicate the extraordinary potential of Q203 to reduce the duration of treatment necessary for cure to ≤ 1 week (or 5 doses of 2-10 mg/kg) in our mouse footpad infection model and warrant further evaluation of Q203 in clinical trials.

Resistance to amoxicillin-clavulanate, a widely used beta-lactam/beta-lactamase inhibitor combination antibiotic, is rising globally, yet susceptibility testing remains challenging. To test whether whole-genome sequencing (WGS) could provide a more reliable assessment of susceptibility than traditional methods, we predicted resistance from WGS for 976 E. coli bloodstream infection isolates from Oxfordshire, UK, comparing against phenotypes from the BD Phoenix (calibrated against EUCAST guidelines). 339/976 (35%) isolates were amoxicillin-clavulanate resistant. Predictions based solely on beta-lactamase presence/absence performed poorly (sensitivity 23% (78/339)) but improved when genetic features associated with penicillinase hyper-production (e.g. promoter mutations, copy number estimates) were considered (sensitivity 82% (277/339); p<0.0001). Most discrepancies occurred in isolates with peri-breakpoint MICs. We investigated two potential causes; the phenotypic reference and the binary resistant/susceptible classification. We performed reference standard, replicated phenotyping in a random stratified subsample of 261/976 (27%) isolates using agar dilution, following both EUCAST and CLSI guidelines, which use different clavulanate concentrations. As well as disagreeing with each other, neither agar dilution phenotype aligned perfectly with genetic features. A random-effects model investigating associations between genetic features and MICs showed that some genetic features had small, variable and additive effects, resulting in variable resistance classification. Using model fixed-effects to predict MICs for the non-agar dilution isolates, predicted MICs were in essential agreement (±1 doubling dilution) with observed (BD Phoenix) MICs for 691/715 (97%) isolates. This suggests amoxicillin-clavulanate resistance in E. coli is quantitative, rather than qualitative, explaining the poorly reproducible binary (resistant/susceptible) phenotypes and suboptimal concordance between different phenotypic methods and with WGS-based predictions.

Objectives: Carbapenemase-producing Enterobacterales and specifically KPC-producing Klebsiella pneumoniae (KPC-Kp) are rapidly spreading worldwide. The prognosis of ventilator-associated pneumonia (VAP) caused by KPC-producing Klebsiella pneumoniae (KPC-Kp) is not well known. Our study tries to assess whether ventilator-associated pneumonia caused by a KPC-Kp strain is associated with higher all-cause mortality than if caused by carbapenem-susceptible isolates.

Study design and methods: This is a retrospective cohort study of patients with VAP due to K. pneumoniae from a 35-bed polyvalent Intensive Care Unit in a university hospital (> 40,000 annual admissions) between January 2012 and December 2016. Adjusted multivariate analysis was used to study the association of KPC-Kp with 30-day all-cause mortality (Cox regression).

Results. We analyze 69 cases of K. pneumoniae VAP of which 39 were produced by a KPC-Kp strain with high-level resistance to meropenem (MIC > 16 mg/mL). All-cause mortality at 30 days was 41% in the KPC-Kp group (16/39) and 33.3% in the carbapenem-susceptible cases (10/30). KPC-Kp etiology was not associated with higher mortality when controlled for confounders (adjusted hazard ratio [lsqb]HR[rsqb] 1.25; 95% CI: 0.46–3.41). Adequate targeted therapy (HR 0.03; 95% CI: <0.01–0.23) was associated with all-cause mortality.

Conclussion. Assuming the limitations due to the available sample size, the prognosis of VAP caused by KPC-Kp is similar to VAPs caused by carbapenem-susceptible K. pneumoniae when appropriate treatment is used.

Highly conserved PenI-type class A β-lactamase in pathogenic members of Burkholderia can evolve to extended-spectrum β-lactamase (ESBL), which exhibits hydrolytic activity towards third-generation cephalosporins, while losing its activity towards the original penicillin substrates. We describe three single-amino-acid-substitution mutations in the ArgS arginine-tRNA synthetase that confer extra antibiotic tolerance protection to ESBL-producing Burkholderia thailandensis. This pathway can be exploited to evade antibiotic tolerance induction in developing therapeutic measures against Burkholderia species, targeting their essential aminoacyl-tRNA synthetases.

QPX7728 is an ultra-broad-spectrum boronic acid beta-lactamase inhibitor with potent inhibition of key serine and metallo beta-lactamases observed in biochemical assays. Microbiological studies using characterized strains were used to provide a comprehensive characterization of the spectrum of beta-lactamase inhibition by QPX7728. The MIC of multiple IV only (ceftazidime, piperacillin, cefepime, ceftolozane and meropenem) and orally bioavailable (ceftibuten, cefpodoxime, tebipenem) antibiotics alone and in combination with QPX7728 (4 μg/ml), as well as comparator agents, were determined against the panels of laboratory strains of P. aeruginosa and K. pneumoniae expressing over 55 diverse serine and metallo beta-lactamases. QPX7728 significantly enhanced the potency of antibiotics against the strains expressing Class A extended spectrum beta-lactamases (CTX-M, SHV, TEM, VEB, PER) and carbapenemases (KPC, SME, NMC-A, BKC-1), consistent with beta-lactamase inhibition demonstrated in biochemical assays. It also inhibits both plasmidic (CMY, FOX, MIR, DHA) and chromosomally encoded (P99, PDC, ADC) Class C beta-lactamases and Class D enzymes including carbapenemases such as OXA-48 from Enterobacteriaceae and OXA enzymes from Acinetobacter baumannii (OXA-23/24/72/58). QPX7728 is also a potent inhibitor of many class B metallo beta-lactamases (NDM, VIM, CcrA1, IMP, GIM but not SPM or L1). Addition of QPX7728 (4 μg/ml) reduced the MICs in a majority of strains to the level observed for the vector alone control, indicative of complete beta-lactamase inhibition. The ultra-broad-spectrum beta-lactamase inhibition profile makes QPX7728 a viable candidate for further development.

Bacteria of the genus Campylobacter are major foodborne pathogens which have become increasingly resistant to clinically important antimicrobial agents (1)....

The Cpx stress response is widespread among Enterobacteriaceae. We have previously reported a mutation in cpxA in a multidrug resistant strain of Klebsiella aerogenes isolated from a patient treated with imipenem. This mutation yields to a single amino acid substitution (Y144N) located in the periplasmic sensor domain of CpxA. In this work, we sought to characterize this mutation in Escherichia coli by using genetic and biochemical approaches. Here, we show that cpxA^Y144N is an activated allele that confers resistance to β-lactams and aminoglycosides in a CpxR-dependent manner, by regulating the expression of the OmpF porin and the AcrD efflux pump, respectively. We also demonstrate the intimate interconnection between Cpx system and peptidoglycan integrity on the expression of an exogenous AmpC β-lactamase by using imipenem as a cell wall active antibiotic or inactivation of penicillin-binding proteins. Moreover, our data indicate that the Y144N substitution abrogates the interaction between CpxA and CpxP and increase phosphotransfer activity on CpxR. Because the addition of a strong AmpC inducer such as imipenem is known to causes abnormal accumulation of muropeptides (disaccharide-pentapeptide, N-acetylglucosamyl-1,6-anhydro-N-acetylmuramyl-l-alanyl-d-glutamy-meso-diaminopimelic-acid-d-alanyl-d-alanine) in the periplasmic space, we propose these molecules activate the Cpx system by displacing CpxP from the sensor domain of CpxA. Altogether, these data could explain why large perturbations to peptidoglycan caused by imipenem lead to mutational activation of the Cpx system and bacterial adaptation through multidrug resistance. These results also validate the Cpx system, in particular the interaction between CpxA and CpxP, as a promising therapeutic target.

QPX7728 is an ultra-broad-spectrum boronic acid beta-lactamase inhibitor that demonstrates inhibition of key serine and metallo beta-lactamases at a nano molar range in biochemical assays with purified enzymes. The broad-spectrum inhibitory activity of QPX7728 observed in biochemical experiments translates into enhancement of the potency of many beta-lactams against strains of target pathogens producing beta-lactamases. The impact of bacterial efflux and permeability on inhibitory potency were determined using isogenic panels of KPC-3 producing isogenic strains of K. pneumoniae and P. aeruginosa and OXA-23-producing strains of A. baumannii with various combinations of efflux and porin mutations. QPX7728 was minimally affected by multi-drug resistance efflux pumps in either Enterobacteriaceae, or in non-fermenters such as P. aeruginosa or A. baumannii. In P. aeruginosa, the potency of QPX7728 was further enhanced when the outer membrane is permeabilized. The potency of QPX7728 in P. aeruginosa is not affected by inactivation of the carbapenem porin OprD. While changes in OmpK36 (but not OmpK35) reduced the potency of QPX7728 (8-16-fold), QPX7728 (4 μg/ml) nevertheless completely reversed KPC-mediated meropenem resistance in strains with porin mutations, consistent with a lesser effect of these mutations on the potency of QPX7728 compared to other agents. The ultra-broad-spectrum beta-lactamase inhibition profile combined with enhancement of the activity of multiple beta-lactam antibiotics with varying sensitivity to the intrinsic resistance mechanisms of efflux and permeability indicate QPX7728 is a useful inhibitor for use with multiple beta-lactam antibiotics.

There is an urgent need for new, potent anti-tuberculosis (TB) drugs with novel mechanisms of action that can be included in new regimens to shorten the treatment period for TB. After screening a library of carbostyrils, we optimized 3, 4-dihydrocarbostyril derivatives and identified OPC-167832 as having potent anti-tuberculosis activity. The minimum inhibitory concentrations of the compound for Mycobacterium tuberculosis ranged from 0.00024 to 0.002 μg/mL. It had bactericidal activity against both growing and intracellular bacilli, and the frequency of spontaneous resistance for Mycobacterium tuberculosis H37Rv was less than 1.91 x 10^-7. It did not show antagonistic effects with other anti-TB agents in an in vitro checkerboard assay. Whole genome and targeted sequencing of resistant isolates to OPC-167832 identified the decaprenylphosphoryl-β-D-ribose 2'-oxidase (DprE1), an essential enzyme for cell wall biosynthesis, as the target of this compound, and further studies demonstrated inhibition of the DprE1 enzymatic activity by OPC-167832. In a mouse model of chronic TB, OPC-167832 showed potent bactericidal activities starting at a dose of 0.625 mg/kg. Further, it exhibited significant combination effects in 2-drug combinations with delamanid, bedaquiline, or levofloxacin. Finally, 3-4 drug regimens comprised of delamanid and OPC-167832 as the core along with bedaquiline, moxifloxacin, or linezolid showed superior efficacy in reducing bacterial burden and preventing relapse compared to the standard treatment regimen. In summary, these results suggest that OPC-167832 is a novel and potent anti-TB agent and regimens containing OPC-167832 and new or repurposed anti-TB drugs may have the potential to shorten the duration of treatment for TB.