Peacebuilding cannot succeed if half the population is excluded from the process. Crisis Group’s research in Sudan, Congo (DRC) and Uganda suggests that peace agreements, post-conflict reconstruction, and governance do better when women are involved.

The approaching elections could be important steps toward reviving democracy in Chad, but only if President Idriss Déby opens political space for the opposition beforehand.

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.

Despite the establishment of anti-corruption agencies, Burundi is facing a deepening corruption crisis that jeopardises prospects for lasting peace and stability.

The crisis that has been occurring in CAR is certainly the most dramatic in its history: more than 600 000 Central Africans are internally displaced or sought refuge in neighbouring countries; according to the United Nations, 1.7 million live in a constant situation of food insecurity and 878 000 need immediate medical assistance; Muslim communities are fleeing Bangui and the western region, subsistence economy no longer exists and the de facto partition of the country, caused by the sectarian violence, is gradually becoming a reality.

All is in place for a violent confrontation in Burundi. The failed coup on 13 May has intensified opposition to President Pierre Nkurunziza’s push for a third term in office. After ten years of peace, Burundi is in danger of reopening the fault lines that once led the country into civil war.

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.

Burundi is back in the spotlight of the world’s media and the agenda of the United Nations Security Council. As recently as two years ago, the country was considered a success story in peacebuilding circles, but now the news is firmly of a negative variety. The UN is trying to prevent a new civil war in a region still haunted by the Rwandan genocide. How did success so quickly turn to failure?

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.

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.

Objectives. The aim of this study was to assess the safety of early oral switch (EOS) prior to 14 days for low-risk Staphylococcus aureus bacteremia (LR-SAB), which is the primary treatment strategy employed at our institution. Usually recommended therapy is 14 days of intravenous (IV) antibiotics.

Methods. All patients with SAB at our hospital were identified between 1 January 2014 and 31 December 2018. Those meeting low-risk criteria (healthcare-associated, no evidence of deep infection or demonstrated involvement of prosthetic material, and no further positive blood cultures after 72-hours) were included in the study. The primary outcome was occurrence of a SAB-related complication within 90 days.

Results. There were 469 SAB episodes during the study period, 100 (21%) of whom met inclusion criteria. EOS was performed in 84 patients. In this group, line infection was the source in 79%, methicillin-susceptible S. aureus caused 95% of SABs and 74% of patients received IV flucloxacillin. The median duration of IV and oral antibiotics in the EOS group was 5 (IQR 4-6) and 10 days (IQR 9-14), respectively. Seventy-one percent of patients received flucloxacillin as their EOS agent. Overall, 86% of oral step-down therapy was with beta-lactams. One patient (1%) undergoing EOS had SAB relapse within 90 days. No deaths attributable to SAB occurred within 90 days.

Conclusions. In this low MRSA prevalence LR-SAB cohort, EOS was associated with a low incidence of SAB-related complications. This was achieved with oral beta-lactam therapy in most patients. Larger prospective studies are needed to confirm these findings.

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.

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.

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.

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.

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.

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.