More than a decade after the Economic Community of Central African States (ECCAS) was requested by the African Union (AU) to give life to a new peace and security architecture, political and security cooperation on the continent is still in need of reinforcement.

L’indifférence internationale est un facteur aggravant pour les conflits dans les petits pays. Cependant, en ce qui concerne la République centrafricaine (RCA), le contexte est paradoxalement différent.

Depuis jeudi et l’attaque de Bangui par les groupes anti-balaka qui viennent de province et sont composés de villageois et d’anciens militaires constitués en milices d’autodéfense, un calme précaire est revenu dans la capitale centrafricaine grâce au déploiement des militaires français.

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.

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).

Tous les éléments d’une confrontation violente sont en place en Burundi. En observant les derniers développements, il semble que les éléments qui ont conduit par le passé à des massacres et à une longue guerre civile au début des années 1990 se remettent en place.

Le 20 août, Pierre Nkurunziza a été investi pour la troisième fois. Son investiture, annoncée le matin même, a eu lieu presque en catimini et les ambassadeurs européens et américains accrédités à Bujumbura étaient visiblement absents tout comme l’Union africaine. La multiplication des assassinats en août a conduit la présidence à organiser l’investiture à la sauvette.

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.

The deteriorating situation in Burundi is a perfect storm of much that undermines stability in Africa today — presidents seeking impunity and power through dubious new terms, authoritarian regimes muzzling opposition and independent media, regional rivalries stalemating efforts to bring peace and outside powers unwilling or unable to act.

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.

States looking to renew NCLB waivers while they transition to new assessments ask to freeze school ratings in place for one year, the Education Department says.

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.

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.

QPX7728 is a new ultra-broad-spectrum inhibitor of serine and metallo beta-lactamases from a class of cyclic boronates that gave rise to vaborbactam. The spectrum and mechanism of beta-lactamase inhibition by QPX7728 were assessed using purified enzymes from all molecular classes. QPX7728 inhibits class A ESBLs (IC₅₀ range 1-3 nM) and carbapenemases such as KPC (IC₅₀ 2.9±0.4 nM) as well as class C P99 (IC₅₀ of 22±8 nM) with a potency that is comparable or higher than recently FDA approved BLIs avibactam, relebactam and vaborbactam. Unlike those other BLIs, QPX7728 is also a potent inhibitor of class D carbapenemases such as OXA-48 from Enterobacteriaceae and OXA enzymes from A. baumannii (OXA-23/24/58, IC₅₀ range 1-2 nM) as well as MBLs such as NDM-1 (IC₅₀ 55±25 nM), VIM-1 (IC₅₀ 14±4 nM) and IMP-1 (IC₅₀ 610±70 nM). Inhibition of serine enzymes by QPX7728 is associated with progressive inactivation with a high efficiency k₂/K ranging from of 6.3 x 10⁴ (for P99) to 9.9 x 10⁵ M^-1 s^-1 (for OXA-23). This inhibition is reversible with variable stability of the QPX7728-beta-lactamase complexes with target residence time ranging from minutes to several hours: 5-20 minutes for OXA carbapenemases from A. baumanii, ~50 minutes for OXA-48 and 2-3 hours for KPC and CTX-M-15. QPX7728 inhibited all tested serine enzymes at 1:1 molar ratio. Metallo-beta-lactamases NDM, VIM, and IMP were inhibited by a competitive mechanism with fast-on-fast-off kinetics, with K_is of 7.5±2.1 nM, 32±14 nM and 240±30 nM for VIM-1, NDM-1 and IMP-1, respectively. QPX7728 ultra-broad-spectrum of BLI inhibition combined with its high potency enables combinations with multiple different beta-lactam antibiotics.

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.

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.

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.

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.

Antimicrobial peptides and proteins play critical roles in the host defense against invading pathogens. We recently discovered that recombinantly expressed human and mouse serum amyloid A1 (rhSAA1 and rmSAA1) proteins have potent antifungal activities against the major human fungal pathogen Candida albicans. At high concentrations, rhSAA1 disrupts C. albicans membrane integrity and induces rapid fungal cell death. In the current study, we find that rhSAA1 promotes cell aggregation and targets the C. albicans cell wall adhesin Als3. Inactivation of ALS3 in C. albicans leads to a striking decrease in cell aggregation and cell death upon rhSAA1 treatment, suggesting that Als3 plays a critical role in SAA1 sensing. We further demonstrate that deletion of the transcriptional regulators controlling the expression of ALS3, such as AHR1, BCR1, and EFG1 in C. albicans results in similar effects to that of the als3/als3 mutant upon rhSAA1 treatment. Global gene expression profiling indicates that rhSAA1 has a discernible impact on the expression of cell wall- and metabolism-related genes, suggesting that rhSAA1 treatment could lead to a nutrient starvation effect on C. albicans cells.

Multi-drug resistance among Gram-negative bacteria is a major global public health threat. Metallo-β-lactamases (MBLs) target the most widely-used antibiotic class, the β-lactams, including the most recent-generation carbapenems. Interspecies spread renders these enzymes a serious clinical threat and there are no clinically-available inhibitors. We present crystal structures of IMP-13, a structurally-uncharacterized MBL from Gram-negative Pseudomonas aerugionasa found in clinical outbreaks globally, and characterize the binding using solution NMR-spectroscopy and molecular-dynamics simulations. Crystal structures of apo IMP-13 and bound to four clinically-relevant carbapenem antibiotics (doripenem, ertapenem, imipenem and meropenem) are presented. Active site plasticity and the active-site loop, where a tryptophan residue stabilizes the antibiotic core scaffold, are essential to the substrate-binding mechanism. The conserved carbapenem scaffold plays the most significant role in IMP-13 binding, explaining the broad substrate specificity. The observed plasticity and substrate-locking mechanism provide opportunities for rational drug design of novel metallo-β-lactamase inhibitors, essential in the fight against antibiotic resistance.

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.

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.

Periodontitis as a biofilm-associated inflammatory disease is highly prevalent worldwide. It severely affects oral health and yet closely links to systemic diseases like diabetes and cardiovascular disease. Porphyromonas gingivalis as a ‘keystone' periodontopathogen drives the shift of microbe-host symbiosis to dysbiosis, and critically contributes to the pathogenesis of periodontitis. Persisters are a tiny subset of biofilm-associated microbes highly tolerant to lethal treatment of antimicrobials, and notably metronidazole-tolerant P. gingivalis persisters have recently been identified by our group. This study further explored the interactive profiles of metronidazole-treated P. gingivalis persisters (M-PgPs) with human gingival epithelial cells (HGECs). P. gingivalis cells (ATCC 33277) at stationary phase were treated with lethal dosage of metronidazole (100 μg/ml, 6 hours) for generating M-PgPs. The interaction of M-PgPs with HGECs was assessed by microscopy, flow cytometry, cytokine profiling and qPCR. We demonstrated that the overall morphology and ultra-cellular structure of M-PgPs remained unchanged. Importantly, M-PgPs maintained the capabilities to adhere to and invade into HGECs. Moreover, M-PgPs significantly suppressed pro-inflammatory cytokine expression in HGECs at a comparable level with the untreated P. gingivalis cells, through the thermo-sensitive components. The present study reveals that P. gingivalis persisters induced by lethal treatment of antibiotics could maintain their capabilities to adhere to and invade into human gingival epithelial cells, and perturb the innate host responses. Novel strategies and approaches need to be developed for tackling P. gingivalis and favourably modulating the dysregulated immuno-inflammatory responses for oral/periodontal health and general wellbeing.

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.

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.

The biologic Griffithsin (GRFT) has recently emerged as a candidate to safely prevent sexually transmitted infections (STIs) including human immunodeficiency virus (HIV-1) and herpes simplex virus 2 (HSV-2). However, to date, there are few delivery platforms that are available to effectively deliver biologics to the female reproductive tract (FRT). The goal of this work was to evaluate rapid-release polyethylene oxide (PEO), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) fibers, that incorporate GRFT, in in vitro (HIV-1 and HSV-2) and in vivo (HSV-2) infection models. GRFT loading was determined via ELISA, and the bioactivity of GRFT fibers was assessed using in vitro HIV-1 pseudovirus and HSV-2 plaque assays. Afterwards, the efficacy of GRFT fibers was assessed in a murine model of lethal HSV-2 infection. Finally, murine reproductive tracts and vaginal lavages were evaluated for histology and cytokine expression, 24 and 72 hr after fiber administration, to determine safety. All rapid-release formulations achieved high levels of GRFT incorporation and were completely efficacious against in vitro HIV-1 and HSV-2 infections. Importantly, all rapid-release GRFT fibers provided potent protection in a murine model of HSV-2 infection. Moreover, histology and cytokine levels, evaluated from collected murine reproductive tissues and vaginal lavages treated with blank fibers, showed no increased cytokine production or histological aberrations, demonstrating the preliminary safety of rapid-release GRFT fibers in vaginal tissue.

Contezolid (MRX-I), a new oxazolidinone, is an antibiotic in development for treating complicated skin and soft tissue infections (cSSTI) caused by resistant Gram-positive bacteria. This was a thorough QT study conducted in 52 healthy subjects who were administered oral contezolid at a therapeutic (800 mg) dose, a supratherapeutic (1600 mg) dose, placebo, and oral moxifloxacin 400 mg in 4 separate treatment periods. The pharmacokinetic profile of contezolid was also evaluated. Time-point analysis indicated that the upper bounds of the two-sided 90% confidence interval (CI) for placebo-corrected change-from-baseline QTc (QTc) were <10 ms for the contezolid therapeutic dose at each time point. The upper bound of the 90% CI for QTc were slightly more than 10 ms with the contezolid supratherapeutic dose at 3 and 4 hours postdose, and the prolongation effect on the QT/QTc interval was less than that of the positive control, moxifloxacin 400 mg. At 3 and 4 h after the moxifloxacin dose, the moxifloxacin group met the assay sensitivity criteria outlined in ICH Guidance E14 with having a lower confidence bound ≥5 ms. The results of a linear exposure-response model which were similar to that of a time point analysis demonstrated a slightly positive relationship between contezolid plasma levels and QTcF interval with a slope of 0.227 ms per mg/L (90% CI: 0.188 to 0.266). In summary, contezolid did not prolong the QT interval at a therapeutic dose and may have a slight effect on QT interval prolongation at a supratherapeutic dose.

Polymyxins are increasingly used as the critical last-resort therapeutic options for multidrug-resistant gram-negative bacteria. Unfortunately, polymyxin resistance has increased gradually for the last few years. Although studies on mechanisms of polymyxin are expanding, system-wide analyses of the underlying mechanism for polymyxin resistance and stress response are still lacking. To understand how Klebsiella pneumoniae adapt to colistin (polymyxin E) pressure, we carried out proteomic analysis of Klebsiella pneumoniae strain cultured with different concentrations of colistin. Our results showed that the proteomic responses to colistin treatment in Klebsiella pneumoniae involving several pathways, including (i) gluconeogenesis and TCA cycle; (ii) arginine biosynthesis; (iii) porphyrin and chlorophyll metabolism; and (iv) enterobactin biosynthesis. Interestingly, decreased abundance of class A β-lactamases including TEM, SHV-11, SHV-4 were observed in cells treated with colistin. Moreover, we also present comprehensive proteome atlases of paired polymyxin-susceptible and -resistant Klebsiella pneumoniae strains. The polymyxin-resistant strain Ci, a mutant of Klebsiella pneumoniae ATCC BAA 2146, showed missense mutation in crrB. The crrB mutant Ci, which displayed lipid A modification with 4-amino-4-deoxy-L-arabinose (L-Ara4N) and palmitoylation, showed striking increases of CrrAB, PmrAB, PhoPQ, ArnBCADT and PagP. We hypothesize that crrB mutations induce elevated expression of the arnBCADTEF operon and pagP via PmrAB and PhoPQ. Moreover, multidrug efflux pump KexD, which was induced by crrB mutation, also contributed to colistin resistance. Overall, our results demonstrated proteomic responses to colistin treatment and the mechanism of CrrB-mediate colistin resistance, which may further offer valuable information to manage polymyxin resistance.

Recent studies highlight the abundance of commensal coagulase-negative staphylococci (CoNS) on healthy skin. Evidence suggests that CoNS actively shape the skin immunological and microbial milieu to resist colonization or infection by opportunistic pathogens, including methicillin resistant Staphylococcus aureus (MRSA), in a variety of mechanisms collectively termed colonization resistance. One potential colonization resistance mechanism is the application of quorum sensing, also called the Accessory Gene Regulator (agr) system, which is ubiquitous among staphylococci. Common and rare CoNS make autoinducing peptides (AIPs) that function as MRSA agr inhibitors, protecting the host from invasive infection. In a screen of CoNS spent media we found that Staphylococcus simulans, a rare human skin colonizer and frequent livestock colonizer, released potent inhibitors of all classes of MRSA agr signaling. We identified three S. simulans agr classes, and have shown intraspecies cross-talk between non-cognate S. simulans agr types for the first time. The S. simulans AIP-I structure was confirmed, and the novel AIP-II and AIP-III structures were solved via mass spectrometry. Synthetic S. simulans AIPs inhibited MRSA agr signaling with nanomolar potency. S. simulans in competition with MRSA reduced dermonecrotic and epicutaneous skin injury in murine models. Addition of synthetic AIP-I also effectively reduced MRSA dermonecrosis and epicutaneous skin injury in murine models. These results demonstrate potent anti-MRSA quorum sensing inhibition by a rare human skin commensal, and suggest that cross-talk between CoNS and MRSA may be important in maintaining healthy skin homeostasis and preventing MRSA skin damage during colonization or acute infection.

Klebsiella pneumoniae that produce extended spectrum beta lactamases (ESBLs) are a persistent public health threat. There are relatively few therapeutic options and there is undue reliance on carbapenems. Alternative therapeutic options are urgently required. A combination of cefepime and the novel beta lactamase inhibitor enmetazobactam is being developed for treatment of serious infections caused by ESBL-producing organisms. The pharmacokinetics-pharmacodynamics (PK-PD) of cefepime-enmetazobactam against ESBL-producing K. pneumoniae was studied in a neutropenic murine pneumonia model. Dose ranging studies were performed. Dose fractionation studies were performed to define the relevant PD index for the inhibitor. The partitioning of cefepime and enmetazobactam into the lung was determined by comparing area under the concentration time curve (AUC) in plasma and epithelial lining fluid. The magnitude of drug exposure for cefepime-enmetazobactam required for logarithmic killing in the lung was defined using 3 ESBL-producing strains. Cefepime 100 mg/kg q8h i.v. had minimal antimicrobial effect. When this background regimen of cefepime was combined with enmetazobactam half-maximal effect was induced with enmetazobactam 4.71 mg/kg q8h i.v. The dose fractionation study suggest both fT>threshold and fAUC:MIC are potentially relevant PD indices. The AUC_ELF:AUC_plasma for cefepime and enmetazobactam was 73.4% and 61.5%, respectively. A ≥2-log kill in the lung was achieved with a plasma and ELF cefepime fT>MIC of ≥20% and enmetazobactam fT>2 mg/L of ≥20% of the dosing interval. These data and analyses provide the underpinning evidence for the combined use of cefepime and enmetazobactam for nosocomial pneumonia.

Chromosomal and plasmid-borne AmpC cephalosporinases are a major resistance mechanism to β-lactams in Enterobacteriaceae and Pseudomonas aeruginosa. The new β-lactamase inhibitor avibactam effectively inhibits class C enzymes and can fully restore ceftazidime susceptibility. The conserved amino acid residue Asn³⁴⁶ of AmpC cephalosporinases directly interacts with the avibactam sulfonate. Disruption of this interaction caused by the N³⁴⁶Y amino acid substitution in Citrobacter freundii AmpC was previously shown to confer resistance to the ceftazidime-avibactam combination (CAZ-AVI). The aim of this study was to phenotypically and biochemically characterize the consequences of the N³⁴⁶Y substitution in various AmpC backgrounds. Introduction of N³⁴⁶Y into Enterobacter cloacae AmpC (AmpC_cloacae), plasmid-mediated DHA-1, and P. aeruginosa PDC-5, led to 270-, 12,000-, and 79-fold decreases in the inhibitory efficacy (k₂/K_i) of avibactam, respectively. The kinetic parameters of AmpC_cloacaeand DHA-1 for ceftazidime hydrolysis were moderately affected by the substitution. Accordingly, AmpC_cloacaeand DHA-1 harboring N³⁴⁶Y conferred CAZ-AVI resistance (MIC of ceftazidime of 16 µg/ml in the presence of 4 µg/ml of avibactam). In contrast, production of PDC-5 N³⁴⁶Y was associated with a lower MIC (4 µg/ml) since this β-lactamase retained a higher inactivation efficacy by avibactam in comparison to AmpC_cloacaeN³⁴⁶Y. For FOX-3, the I³⁴⁶Y substitution did not reduce the inactivation efficacy of avibactam and the substitution was highly deleterious for β-lactam hydrolysis, including ceftazidime, preventing CAZ-AVI resistance. Since AmpC_cloacaeand DHA-1 display substantial sequence diversity, our results suggest that loss of hydrogen interaction between Asn³⁴⁶ and avibactam could be a common mechanism of acquisition of CAZ-AVI resistance.

Probiotics might provide an alternative approach for the control of oral candidiasis. However, studies on the antifungal activity of probiotics in the oral cavity are based on the consumption of yogurt or other dietary products, and there is a necessary to use appropriate biomaterials and specific strains to obtain probiotic formulations targeting local oral administration. In this study, we impregnated gellan gum, a natural biopolymer used as a food-additive, with a probiotic and investigated its antifungal activity against Candida albicans. Lactobacillus paracasei 28.4, a strain recently isolated from the oral cavity of a caries-free individual, was incorporated in several concentrations of gellan gum (0.6% to 1%). All tested concentrations could incorporate L. paracasei cells while maintaining bacterial viability. Probiotic/gellan formulations were stable for 7 days when stored at room temperature or 4°C. Long-term storage of bacteria-impregnated gellan gum was achieved when L. paracasei 28.4 was lyophilized. The probiotic/gellan formulations provided a release of L. paracasei cells over 24 hours that was sufficient to inhibit the growth of C. albicans with effects dependent on the cell concentrations incorporated into gellan gum. The probiotic/gellan formulations also had inhibitory activity against Candida spp. biofilms by reducing the number of Candida spp. cells (p < 0.0001), decreasing the total biomass (p = 0.0003), and impairing hyphae formation (p = 0.0002), compared to the control group which received no treatment. Interestingly, probiotic formulation of 1% w/v gellan gum provided an oral colonization of L. paracasei in mice with approximately 6 log of CFU/mL after 10 days. This formulation inhibited the C. albicans growth (p < 0.0001), prevented the development of candidiasis lesions (p = 0.0013), and suppressed inflammation (p = 0.0006) when compared to the mice not treated in the microscopic analysis of the tongue dorsum. These results indicate that gellan gum is a promising biomaterial and can be used as a carrier system to promote oral colonization for probiotics that prevent oral candidiasis.

Durlobactam (DUR, also known as ETX2514) is a novel β-lactamase inhibitor with broad activity against Ambler class A, C, and D β-lactamases. Addition of DUR to sulbactam (SUL) in vitro restores SUL activity against clinical isolates of Acinetobacter baumannii. The safety and pharmacokinetics (PK) of DUR alone and with SUL and/or imipenem/cilastatin (IMI/CIL) were evaluated in healthy subjects. This was a randomized, placebo-controlled study. In Part A, subjects including an elderly cohort (DUR 1 g) received single ascending doses of DUR 0.25-8 g. In Part B, multiple ascending dose of DUR 0.25-2 g were administered every 6 hours (q6h) for 29 doses. In Parts C and D, the drug-drug interaction (DDI) potential, including safety, of DUR (1 g) with SUL (1 g) and/or IMI/CIL (0.5/0.5 g) was investigated after single and multiple doses. Plasma and urine concentrations of DUR, SUL, and IMI/CIL were determined. Among 124 subjects, DUR was generally safe and well tolerated either alone or in combination with SUL and/or IMI/CIL. After single and multiple doses, DUR demonstrated linear dose proportional exposure across the studied dose ranges. Renal excretion was a predominant clearance mechanism. No drug:drug interaction potential was identified between DUR and SUL and/or IMI/CIL. SUL-DUR, 1 g (of each component) administered q6h with a 3 hour IV infusion, is under development for the treatment of serious infections due to A. baumannii.

Bunyaviruses are significant human pathogens, causing diseases ranging from hemorrhagic fevers to encephalitis. Among these viruses, La Crosse virus (LACV), a member of the California serogroup, circulates in the eastern and midwestern United States. While LACV infection is often asymptomatic, dozens of cases of encephalitis are reported yearly. Unfortunately, no antivirals have been approved to treat LACV infection. Here, we developed a method to rapidly test potential antivirals against LACV infection. From this screen, we identified several potential antiviral molecules, including known antivirals. Additionally, we identified many novel antivirals that exhibited antiviral activity without affecting cellular viability. Valinomycin, a potassium ionophore, was among our top targets. We found that valinomycin exhibited potent anti-LACV activity in multiple cell types in a dose-dependent manner. Valinomycin did not affect particle stability or infectivity, suggesting that it may preclude virus replication by altering cellular potassium ions, a known determinant of LACV entry. We extended these results to other ionophores and found that the antiviral activity of valinomycin extended to other viral families including bunyaviruses (Rift Valley fever virus, Keystone virus), enteroviruses (Coxsackievirus, rhinovirus), flavirivuses (Zika), and coronaviruses (HCoV-229E and MERS-CoV). In all viral infections, we observed significant reductions in virus titer in valinomycin-treated cells. In sum, we demonstrate the importance of potassium ions to virus infection, suggesting a potential therapeutic target to disrupt virus replication.

Importance No antivirals are approved for the treatment of bunyavirus infection. The ability to rapidly screen compounds and identify novel antivirals is one means to accelerate drug discovery for viruses with no approved treatments. We used this approach to screen hundreds of compounds against La Crosse virus, an emerging bunyavirus that causes significant disease, including encephalitis. We identified several known and previously unidentified antivirals. We focused on a potassium ionophore, valinomycin, due to its promising in vitro antiviral activity. We demonstrate that valinomycin, as well as a selection of other ionophores, exhibits activity against La Crosse virus as well as several other distantly related bunyaviruses. We finally observe that valinomycin has activity against a wide array of human viral pathogens, suggesting that disrupting potassium ion homeostasis with valinomycin may be a potent host pathway to target to quell virus infection.

Gepotidacin, a triazaacenaphthylene bacterial type II topoisomerase inhibitor, is in development for treatment of uncomplicated urinary tract infection (uUTI). This Phase 2a study in female participants with uUTI evaluated the pharmacokinetics (primary objective), safety, and exploratory efficacy of gepotidacin. Eligible participants (N = 22) were confined to the clinic at baseline, received oral gepotidacin 1,500 mg twice daily for 5 days (on-therapy; Days 1 to 5), and returned to the clinic for test-of-cure (Days 10 to 13) and follow-up (Day 28±3). Pharmacokinetic, safety, clinical, and microbiological assessments were performed. Maximum plasma concentrations were observed approximately 1.5 to 2 hours postdose. Steady state was attained by Day 3. Urinary exposure over the dosing interval increased from 3,742 μg.h/ml (Day 1) to 5,973 μg.h/ml (Day 4), with trough concentrations of 322 to 352 μg/ml from Day 3 onward. Gepotidacin had an acceptable safety-risk profile with no treatment-limiting adverse events and no clinically relevant safety trends. Clinical success was achieved in 19 (86%) and 18 (82%) of 22 participants at test-of-cure and follow-up, respectively. Eight participants had a qualifying baseline uropathogen (growth; ≥10⁵ CFU/ml). A therapeutic (combined clinical and microbiological [no growth; <10³ CFU/ml]) successful response was achieved in 6 (75%) and 5 (63%) of 8 participants at test-of-cure and follow-up, respectively. Plasma area under the free-drug concentration-time curve over 24 hours at steady state divided by the MIC (fAUC_0-24/MIC) and urine AUC_0-24/MIC ranged from 6.99 to 90.5 and 1,292 to 121,698, respectively. Further evaluation of gepotidacin in uUTI is warranted. (NCT03568942)

The SHV β-lactamases (BLs) have undergone strong allele diversification that changed their substrate specificities. Based on 147 NCBI entries for SHV alleles, in silico mathematical models predicted five positions as relevant for the β-lactamase inhibitor (BLI) resistant (2br) phenotype, 12 as relevant for the extended-spectrum BL (ESBL) (2be) phenotype, and two positions were related to solely the narrow spectrum (2b) phenotype. These positions and additional 6 positions described in other studies (including one promoter mutation), were systematically substituted and investigated for their substrate specificities in a BL-free E. coli background, representing, to our knowledge, the most comprehensive substrate and substitution analysis for SHV alleles to date. An in vitro analysis confirmed the essentiality of the positions 238 and 179 for the 2be phenotype and 69 for the 2br phenotype. The substitutions E240K and E240R, which do not occur alone in known 2br SHV variants, led to a 2br phenotype, indicating a latent BLI-resistance potential of these substitutions. The substitutions M129V, A234G, S271I and R292Q conferred latent resistance to cefotaxime. In addition, 7 positions that were found to be not always associated with the ESBL phenotype resulted in increased resistance to ceftaroline. We also observed that coupling of a strong promoter (IS26) to a A146V mutant with the 2b phenotype resulted in a highly increased resistance to BLIs, cefepime and ceftaroline but not to 3^rd generation cephalosporins, indicating that SHV enzymes represent an underestimated risk for empirical therapies that use piperacillin/tazobactam or cefepime to treat different infectious diseases caused by gram-negatives.

Attention has been paid to H5N6 highly pathogenic avian influenza virus (HPAIV) because of its heavy burden on the poultry industry and human mortality. Since an influenza A virus carrying N6 neuraminidase (NA) has never spread in humans, the potential for H5N6 HPAIV to cause disease in humans and the efficacy of antiviral drugs against the virus need to be urgently assessed. We used non-human primates to elucidate the pathogenesis of H5N6 HPAIV as well as to determine the efficacy of antiviral drugs against the virus. H5N6 HPAIV infection led to high fever in cynomolgus macaques. The lung injury caused by the virus was severe with diffuse alveolar damage and neutrophil infiltration. In addition, an increase in IFN-α showed an inverse correlation with virus titers during the infection process. Oseltamivir was effective for reducing H5N6 HPAIV propagation, and continuous treatment with peramivir reduced virus propagation and severity of symptoms in the early stage. This study also showed the pathologically severe lung injury states in the cynomolgus macaques infected with H5N6 HPAIV, even in those that received early antiviral drug treatments, indicating the need for close monitoring and the need for further studies on the virus pathogenicity and new antiviral therapies.

A total of 2,283 Salmonella spp. isolates were recovered from 18,334 samples including patients with diarrhea, food of animal origin and pets across 5 provinces of China. The highest prevalence of Salmonella spp. was detected in chicken meats (39.3%, 486/1,237). Fifteen serogroups and 66 serovars were identified, with Typhimurium and Enteritidis being the most dominant. Most (85.5%, 1,952/2,283) isolates exhibited resistant to ≥ 1 antimicrobial and 56.4% were multi-drug resistant (MDR). A total of 222 isolates harbored extended-spectrum β-lactamases (ESBLs), 200 of which were CTX-M-type that were mostly detected from chicken meat and turtle fecal. Overall, eight bla_CTX-M genes were identified, with bla_CTX-M-65, bla_CTX-M-123, bla_CTX-M-14, bla_CTX-M-79, and bla_CTX-M-130 being the most prevalent. Totally, 166 of the 222 ESBL-producing isolates had amino acid substitutions in GyrA (S83Y, S83F, D87G, D87N, and D87Y) and ParC (and S80I), whilst the PMQR-encoding genes oqxA/B, qepA, and qnrB/S were detected in almost all isolates. Of the fifteen sequence types (STs) identified in the 222 ESBLs, ST17, ST11, ST34, and ST26 ranked among the top 5 in the number of isolates. Our study revealed considerable serovars diversity, high prevalence of co-occurrence of MDR determinants, including CTX-M-type ESBLs, QRDRs mutations and PMQR genes. This is the first report of CTX-M-130 Salmonella spp. from patients with diarrhea and QRDRs mutations from turtle fecal samples. Our study emphasizes the importance of actions, both in the health care settings and in the veterinary medicine sector, to control the dissemination of MDR, especially the CTX-M Salmonella spp. isolates.

Baloxavir marboxil, a prodrug of cap-dependent endonuclease inhibitor, baloxavir acid, reduces the time to improvement of influenza symptoms in patients infected with type A or B influenza virus. To characterize its pharmacokinetics, a population pharmacokinetic model for baloxavir acid was developed using 11846 plasma concentration data items from 1827 subjects including 2341 plasma concentration data items from 664 patients at high risk of influenza complications. A three-compartment model with first-order elimination and first-order absorption with lag time well described the plasma concentration data. Body weight and race were found to be the most important factors influencing clearance and volume of distribution. The exposures in high-risk patients were similar to those in otherwise healthy patients, and no pharmacokinetic difference was identified regarding any risk factors for influenza complications.

Exposure-response analyses were performed regarding the time to improvement of symptoms and the reduction in the influenza virus titer in high-risk patients. The analyses suggested that body weight-based dosage, 40 mg for patients weighing < 80 kg and 80 mg for patients weighing ≥ 80 kg, can shorten the time to improvement of influenza symptoms and reduce virus titer for both type A and B influenza virus regardless of the exposure levels of the high-risk patients as well as for the otherwise healthy influenza patients.

The results of our population pharmacokinetic and exposure-response analyses in patients with risk factors of influenza complications should provide useful information on the pharmacokinetic and pharmacodynamic characteristics of baloxavir marboxil and also for the optimization of dose regimens.

Meropenem/vaborbactam resistance in Klebsiella pneumoniae is associated with loss of function mutations in the OmpK35 and OmpK36 porins. Here we identify two previously unknown loss of function mutations that confer cefuroxime resistance in K. pneumoniae. The proteins lost were NlpD and KvrA; the latter is a transcriptional repressor controlling capsule production. We demonstrate that KvrA loss reduces OmpK35 and OmpK36 porin production, which confers reduced susceptibility to meropenem/vaborbactam in a KPC-3 producing K. pneumoniae isolate.

Objectives: Empiric antibiotic prescribing can be supported by guidelines and/or local antibiograms, but these have limitations. We sought to use data from a comprehensive electronic health record to use statistical learning to develop predictive models for individual antibiotics that incorporate patient-, and hospital-specific factors. This paper reports on the development and validation of these models on a large retrospective cohort.

Methods: This is a retrospective cohort study including hospitalized patients with positive urine cultures in the first 48 hours of hospitalization at a 1500 bed, tertiary care hospital over a 4.5 year period. All first urine cultures with susceptibilities were included. Statistical learning techniques, including penalized logistic regression, were used to create predictive models for cefazolin, ceftriaxone, ciprofloxacin, cefepime, and piperacillin-tazobactam. These were validated on a held-out cohort.

Results: The final dataset used for analysis included 6,366 patients. Final model covariates included demographics, comorbidity score, recent antibiotic use, recent antimicrobial resistance, and antibiotic allergies. Models had acceptable to good discrimination in the training dataset and acceptable performance in the validation dataset, with a point estimate for area under the receiver operating characteristic curve (AUC) that ranged from 0.65 for ceftriaxone to 0.69 for cefazolin. All models had excellent calibration.

Conclusion: In this study we used electronic health record data to create predictive models to estimate antibiotic susceptibilities for UTIs in hospitalized patients. Our models had acceptable performance in a held-out validation cohort.

Aspergillus niger, the third species responsible for invasive aspergillosis has been considered as a homogeneous species until DNA-based identification uncovered many cryptic species. These species have been recently reclassified into the Aspergillus section Nigri. However little is yet known among the section Nigri about the species distribution and the antifungal susceptibility pattern of each cryptic species. A total of 112 clinical isolates collected from 5 teaching hospitals in France and phenotypically identified as A. niger were analyzed. Identification to the species level was carried out by nucleotide sequence analysis. The Minimum Inhibitory Concentrations (MICs) of itraconazole, voriconazole, posaconazole, isavuconazole and amphotericin B were determined by both the EUCAST and gradient concentration strips methods. Aspergillus tubingensis (n=51, 45.5%) and A. welwitschiae (n=50, 44.6%) were the most common species while A. niger accounted for only 6.3% (n=7). The MICs of azoles drugs were higher for A. tubingensis than for A. welwitschiae. The MIC of amphotericin B was 2 mg/L or less for all isolates. Importantly, MICs determined by EUCAST showed no correlation with those determined by gradient concentration strips methods, these latter being lower than the former (Spearman's rank correlation tests ranging - depending on the antifungal agent - from 0.01 to 0.25; p>0.4). In conclusion, A. niger should be considered as a minority species in the section Nigri. The differences in MICs between species for different azoles underline the importance of accurate identification. Significant divergences in the determination of MIC between EUCAST and gradient concentration strips methods require further investigation.