Ceftazidime (CAZ)-avibactam (AVI) is a β-lactam/β-lactamase inhibitor combination with activity against type A and type C β-lactamases. Resistance emergence has been seen, with multiple mechanisms ...accounting for the resistance. We performed four experiments in the dynamic hollow-fiber infection model, delineating the linkage between drug exposure and both the rate of bacterial kill and resistance emergence by all mechanisms. The Pseudomonas aeruginosa isolate had MICs of 1.0 mg/liter (CAZ) and 4 mg/liter (AVI). We demonstrated that the time at ≥4.0 mg/liter AVI was linked to the rate of bacterial kill. Linkage to resistance emergence/suppression was more complex. In one experiment in which CAZ and AVI administration was intermittent and continuous, respectively, and in which AVI was given in unitary steps from 1 to 8 mg/liter, AVI at up to 3 mg/liter allowed resistance emergence, whereas higher values did not. The threshold value was 3.72 mg/liter as a continuous infusion to counterselect resistance (AVI area under the concentration-time curve AUC of 89.3 mg · h/liter). The mechanism involved a 7-amino-acid deletion in the Ω-loop region of the Pseudomonas-derived cephalosporinase (PDC) β-lactamase. Further experiments in which CAZ and AVI were both administered intermittently with regimens above and below the AUC of 89.3 mg · h/liter resulted in resistance in the lower-exposure groups. Deletion mutants were not identified. Finally, in an experiment in which paired exposures as both continuous and intermittent infusions were performed, the lower value of 25 mg · h/liter by both profiles allowed selection of deletion mutants. Of the five instances in which these mutants were recovered, four had a continuous-infusion profile. Both continuous-infusion administration and low AVI AUC exposures have a role in selection of this mutation.
Ceftazidime (CAZ)-avibactam (AVI) is a β-lactam/β-lactamase inhibitor combination with activity against type A and type C β-lactamases. Resistance emergence has been seen, with multiple mechanisms ...accounting for the resistance. We performed four experiments in the dynamic hollow-fiber infection model, delineating the linkage between drug exposure and both the rate of bacterial kill and resistance emergence by all mechanisms. The
isolate had MICs of 1.0 mg/liter (CAZ) and 4 mg/liter (AVI). We demonstrated that the time at ≥4.0 mg/liter AVI was linked to the rate of bacterial kill. Linkage to resistance emergence/suppression was more complex. In one experiment in which CAZ and AVI administration was intermittent and continuous, respectively, and in which AVI was given in unitary steps from 1 to 8 mg/liter, AVI at up to 3 mg/liter allowed resistance emergence, whereas higher values did not. The threshold value was 3.72 mg/liter as a continuous infusion to counterselect resistance (AVI area under the concentration-time curve AUC of 89.3 mg · h/liter). The mechanism involved a 7-amino-acid deletion in the Ω-loop region of the
-derived cephalosporinase (PDC) β-lactamase. Further experiments in which CAZ and AVI were both administered intermittently with regimens above and below the AUC of 89.3 mg · h/liter resulted in resistance in the lower-exposure groups. Deletion mutants were not identified. Finally, in an experiment in which paired exposures as both continuous and intermittent infusions were performed, the lower value of 25 mg · h/liter by both profiles allowed selection of deletion mutants. Of the five instances in which these mutants were recovered, four had a continuous-infusion profile. Both continuous-infusion administration and low AVI AUC exposures have a role in selection of this mutation.
Abstract Purpose Recent doubts regarding the efficacy may have resulted in a loss of interest for targeted temperature management (TTM) in comatose cardiac arrest (CA) patients, with uncertain ...consequences on outcome. We aimed to identify a change in TTM use and to assess the relationship between this change and neurological outcome. Methods We used Utstein data prospectively collected in the Sudden Death Expertise Center (SDEC) registry (capturing CA data from all secondary and tertiary hospitals located in the Great Paris area, France) between May 2011 and December 2017. All cases of non-traumatic OHCA patients with stable return of spontaneous circulation (ROSC) were included. After adjustment for potential confounders, we assessed the relationship between changes over time in the use of TTM and neurological recovery at discharge using the Cerebral Performance Categories (CPC) scale. Results Between May 2011 and December 2017, 3925 patients were retained in the analysis, of whom 1847 (47%) received TTM. The rate of good neurological outcome at discharge (CPC 1 or 2) was higher in TTM patients as compared with no TTM (33% vs 15%, P < 0.001). Gender, age, and location of CA did not change over the years. Bystander CPR increased from 55% in 2011 to 73% in 2017 ( P < 0.001) and patients with a no-flow time longer than 3 min decreased from 53 to 38% ( P < 0.001). The use of TTM decreased from 55% in 2011 to 37% in 2017 ( P < 0.001). Meanwhile, the rate of patients with good neurological recovery remained stable (19 to 23%, P = 0.76). After adjustment, year of CA occurrence was not associated with outcome. Conclusions We report a progressive decrease in the use of TTM in post-cardiac arrest patients over the recent years. During this period, neurological outcome remained stable, despite an increase in bystander-initiated resuscitation and a decrease in “no flow” duration.
Ventilator-associated bacterial pneumonia (VABP) is a difficult therapeutic problem. Considerable controversy exists regarding the optimal chemotherapy for this entity. The recent guidelines of the ...Infectious Diseases Society of America and the American Thoracic Society recommend a 7-day therapeutic course for VABP based on the balance of no negative impact on all-cause mortality, less resistance emergence, and fewer antibiotic treatment days, counterbalanced with a higher relapse rate for patients whose pathogen is a nonfermenter. The bacterial burden causing an infection has a substantial impact on treatment outcome and resistance selection. We describe the baseline bronchoalveolar lavage (BAL) fluid burden of organisms in suspected VABP patients screened for inclusion in a clinical trial. We measured the urea concentrations in plasma and BAL fluid to provide an index of the dilution of the bacterial and drug concentrations in the lung epithelial lining fluid introduced by the BAL procedure. We were then able to calculate the true bacterial burden as the diluted colony count times the dilution factor. The median dilution factor was 28.7, with the interquartile range (IQR) being 11.9 to 53.2. Median dilution factor-corrected colony counts were 6.18 log
(CFU/ml) IQR, 5.43 to 6.46 log
(CFU/ml). In a subset of patients, repeat BAL on day 5 showed a good stability of the dilution factor. We previously showed that large bacterial burdens reduce or stop bacterial killing by granulocytes. (This study has been registered at ClinicalTrials.gov under registration no. NCT01570192.).
We report the characterization and optimization of drug-like small molecule inhibitors of tissue-nonspecific alkaline phosphatase (TNAP), an enzyme critical for the regulation of extracellular matrix ...calcification during bone formation and growth. High-throughput screening (HTS) of a small molecule library led to the identification of arylsulfonamides as potent and selective inhibitors of TNAP. Critical structural requirements for activity were determined, and the compounds were subsequently profiled for in vitro activity and bioavailability parameters including metabolic stability and permeability. The plasma levels following subcutaneous administration of a member of the lead series in rat was determined, demonstrating the potential of these TNAP inhibitors as systemically active therapeutic agents to target various diseases involving soft tissue calcification. A representative member of the series was also characterized in mechanistic and kinetic studies.
Abstract
Background
FOS (ZTI-01, fosfomycin for injection) is an epoxide antibiotic that covalently binds MurA, an earlier step in cell wall synthesis inhibition. FOS has demonstrated synergistic ...killing with other classes of agents, including carbapenems. PA, among other non-fermentors, are difficult to treat pathogens and combination therapy is important to ensure killing and suppress emergence of resistance. Here, we examine the combination of FOS + MER in the HFIM against PA.
Methods
The experimental design was fully factorial (3 FOS and 3 MER arms and all combinations). Simulated FOS doses were 4, 6 and 8 g 8 hourly (Q8). MER doses were 0.5, 1 and 2 g Q8. The experiment lasted 10 days. Concentrations from the central compartment were measured in all arms by LC/MS/MS. Total bacterial burden and resistant subpopulations for both drugs were measured. Resistance plates were infused with 3XBaseline MIC. Starting inoculum was 6.86 Logs.
Results
FOS/MER MIC’s were 64 mg/L (broth) and 0.5 mg/L. Mutational frequency to resistance were -5.27 (FOS) and -6.7 (MER). There were 15 drug-containing arms and a no-treatment control. All drug arms had concentration-time profiles accurately reproduced. All FOS alone arms had rapid resistance emergence. MER 0.5 gm alone had resistance emerge at Day1. FOS 4 g + MER 0.5 g allowed resistance to both agents as did FOS 6g + MER 0.5 g. FOS 6 g + MER 1 g allowed MER resistance, but not FOS. All other combination regimens fully suppressed all resistant mutants. The effect of combination therapy is shown in Figures 1–3. MIC’s for MER-resistant isolates were 2 mg/L early and up to 16 mg/L late (day4 and after). FOS-resistant isolates generally had MIC values between 128 and >1024 mg/L.
Conclusion
The combination of FOS + MER is promising for therapy of a wild-type PA. Doses of FOS of 6 and 8 g Q8 tended to suppress resistance emergence to either agent when combined with 1 or 2 g Q8 of MER. We intend on examining the impact of resistance mutations to MER (oprD downregulated and MexAB upregulated) with this combination to identify any potential therapeutic advantage of this combination regimen
Disclosures
G. L. Drusano, Zavante: Scientific Advisor, Consulting fee
A high-throughput screen of the NIH’s MLSMR collection of ∼340000 compounds was undertaken to identify compounds that inhibit Plasmodium falciparum glucose-6-phosphate dehydrogenase (PfG6PD). PfG6PD ...is important for proliferating and propagating P. falciparum and differs structurally and mechanistically from the human orthologue. The reaction catalyzed by glucose-6-phosphate dehydrogenase (G6PD) is the first, rate-limiting step in the pentose phosphate pathway (PPP), a key metabolic pathway sustaining anabolic needs in reductive equivalents and synthetic materials in fast-growing cells. In P. falciparum, the bifunctional enzyme glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase (PfGluPho) catalyzes the first two steps of the PPP. Because P. falciparum and infected host red blood cells rely on accelerated glucose flux, they depend on the G6PD activity of PfGluPho. The lead compound identified from this effort, (R,Z)-N-((1-ethylpyrrolidin-2-yl)methyl)-2-(2-fluorobenzylidene)-3-oxo-3,4-dihydro-2H-benzob1,4thiazine-6-carboxamide, 11 (ML276), is a submicromolar inhibitor of PfG6PD (IC50 = 889 nM). It is completely selective for the enzyme’s human isoform, displays micromolar potency (IC50 = 2.6 μM) against P. falciparum in culture, and has good drug-like properties, including high solubility and moderate microsomal stability. Studies testing the potential advantage of inhibiting PfG6PD in vivo are in progress.
A scaffold-hop program seeking full agonists of the neurotensin-1 (NTR1) receptor identified the probe molecule ML301 (1) and associated analogs, including its naphthyl analog (14) which exhibited ...similar properties. Compound 1 showed full agonist behavior (79-93%) with an EC50 of 2.0-4.1μM against NTR1. Compound 1 also showed good activity in a Ca mobilization FLIPR assay (93% efficacy at 298nM), consistent with it functioning via the Gq coupled pathway, and good selectivity relative to NTR2 and GPR35. In further profiling, 1 showed low potential for promiscuity and good overall pharmacological data. This report describes the discovery, synthesis, and SAR of 1 and associated analogs. Initial in vitro pharmacologic characterization is also presented.
NOD1 (nucleotide-binding oligomerization domain 1) protein is a member of the NLR (NACHT and leucine rich repeat domain containing proteins) protein family, which plays a key role in innate immunity ...as a sensor of specific microbial components derived from bacterial peptidoglycans and induction of inflammatory responses. Mutations in NOD proteins have been associated with various inflammatory diseases that affect NF-κB (nuclear factor κB) activity, a major signaling pathway involved in apoptosis, inflammation, and immune response. A luciferase-based reporter gene assay was utilized in a high-throughput screening program conducted under the NIH-sponsored Molecular Libraries Probe Production Center Network program to identify the active scaffolds. Herein, we report the chemical synthesis, structure–activity relationship studies, downstream counterscreens, secondary assay data, and pharmacological profiling of the 2-aminobenzimidazole lead (compound 1c, ML130) as a potent and selective inhibitor of NOD1-induced NF-κB activation.
PDF
