Class Of Antibacterial Agents Research Articles

Partitioning of Seven Different Classes of Antibiotics into LPS Monolayers Supports Three Different Permeation Mechanisms through the Outer Bacterial Membrane.

The outer membrane (OM) of Gram-negative (G-) bacteria presents a barrier for many classes of antibacterial agents. Lipopolysaccharide (LPS), present in the outer leaflet of the OM, is stabilized by divalent cations and is considered to be the major impediment for antibacterial agent permeation. However, the actual affinities of major antibiotic classes toward LPS have not yet been determined. In the present work, we use Langmuir monolayers formed from E. coli Re and Rd types of LPS to record pressure-area isotherms in the presence of antimicrobial agents. Our observations suggest three general types of interactions. First, some antimicrobials demonstrated no measurable interactions with LPS. This lack of interaction in the case of cefsulodin, a third-generation cephalosporin antibiotic, correlates with its low efficacy against G- bacteria. Ampicillin and ciprofloxacin also show no interactions with LPS, but in contrast to cefsulodin, both exhibit good efficacy against G- bacteria, indicating permeation through common porins. Second, we observe substantial intercalation of the more hydrophobic antibiotics, novobiocin, rifampicin, azithromycin, and telithromycin, into relaxed LPS monolayers. These largely repartition back to the subphase with monolayer compression. We find that the hydrophobic area, charge, and dipole all show correlations with both the mole fraction of antibiotic retained in the monolayer at the monolayer-bilayer equivalence pressure and the efficacies of these antibiotics against G- bacteria. Third, amine-rich gentamicin and the cationic antimicrobial peptides polymyxin B and colistin show no hydrophobic insertion but are instead strongly driven into the polar LPS layer by electrostatic interactions in a pressure-independent manner. Their intercalation stably increases the area per molecule (by up to 20%), which indicates massive formation of defects in the LPS layer. These defects support a self-promoted permeation mechanism of these antibiotics through the OM, which explains the high efficacy and specificity of these antimicrobials against G- bacteria.

A high-throughput cell-based assay pipeline for the preclinical development of bacterial DsbA inhibitors as antivirulence therapeutics

Antibiotics are failing fast, and the development pipeline remains alarmingly dry. New drug research and development is being urged by world health officials, with new antibacterials against multidrug-resistant Gram-negative pathogens as the highest priority. Antivirulence drugs, which inhibit bacterial pathogenicity factors, are a class of promising antibacterials, however, their development is stifled by lack of standardised preclinical testing akin to what guides antibiotic development. The lack of established target-specific microbiological assays amenable to high-throughput, often means that cell-based testing of virulence inhibitors is absent from the discovery (hit-to-lead) phase, only to be employed at later-stages of lead optimization. Here, we address this by establishing a pipeline of bacterial cell-based assays developed for the identification and early preclinical evaluation of DsbA inhibitors, previously identified by biophysical and biochemical assays. Inhibitors of DsbA block oxidative protein folding required for virulence factor folding in pathogens. Here we use existing Escherichia coli DsbA inhibitors and uropathogenic E. coli (UPEC) as a model pathogen, to demonstrate that the combination of a cell-based sulfotransferase assay and a motility assay (both DsbA reporter assays), modified for a higher throughput format, can provide a robust and target-specific platform for the identification and evaluation of DsbA inhibitors.

QcrB in Mycobacterium tuberculosis: The new drug target of antitubercular agents

Drug-resistance in mycobacterial infections is a major global health problem that leads to high mortality and socioeconomic pressure in developing countries around the world. From finding new targets to discovering novel chemical scaffolds, there is an urgent need for the development of better approaches for the cure of tuberculosis. Recently, energy metabolism in mycobacteria, particularly the oxidative phosphorylation pathway of cellular respiration, has emerged as a novel target pathway in drug discovery. New classes of antibacterials which target oxidative phosphorylation pathway either by interacting with a protein or any step in the pathway of oxidative phosphorylation can combat dormant mycobacterial infections leading to shortening of tuberculosis chemotherapy. Adenosine triphosphate synthase is one such recently discovered target of the newly approved antitubercular drug bedaquiline. Cytochrome bcc is another new target of the antitubercular drug candidate Q203, currently in phase II clinical trial. Research suggests that b subunit of cytochrome bcc, QcrB, is the target of Q203. The review article describes the structure, function, and importance of targeting QcrB throwing light on all chemical classes of QcrB inhibitors discovered to date. An understanding of the structure and function of validated targets and their inhibitors would enable the development of new chemical entities.

Broad Spectrum Antibacterial Ocotillol-Type Derivatives: Semi-Synthesis, Structure-Activity Relationship, and Membrane-Active Mode of Action

A series of 3-amino substituted ocotillol-type derivatives were designed and synthesized for the first time. The in vitro antibacterial activity tests showed that some of the new compounds exhibited excellent antibacterial activity. Compound 13d, which was the most active one, displayed particularly strong antibacterial activity against S. aureus, B. subtilis, MRSA (methicillin-resistant S. aureus) and E. coli with minimum inhibitory concentration (MIC) values of 1-4 μg mL-1. Further research also suggested that 13d showed low cytotoxicity to human normal cells HEK-293 and L02, strong synergistic effects with kanamycin or chloramphenicol and a broad antibacterial spectrum including against multidrug-resistant strains. This active molecule 13d also induced bacterial resistance more slowly than norfloxacin and colistin. Furthermore, the research results demonstrated that this type of compounds could disperse the established bacterial biofilms, thus suppressing or delaying the development of drug resistance. Mechanism studies have shown that compound 13d could damage the integrity of cell membranes, which in turn facilitated the antibacterial agents binding to deoxyribonucleic acid (DNA), leading to cell death. Therefore, these results indicated that the membrane active ocotillol-type derivatives are a promising class of antibacterial agents to fight against super bacteria and deserve further attention.

214. Antibiotic Use for Common Infections in British Columbia: A Review of Outpatient Prescribing from 2000 - 2018

BackgroundAntimicrobial resistance continues to jeopardize the future of modern medicine; as 92% of all antibiotics are used in the community, it is imperative to parse outpatient prescribing. In British Columbia (BC), efforts to curb the use of these essential medications have included: stewardship campaigns, practitioner guidelines, and vaccine scheduling amendments. This study reviews the trends in antibiotic use over the past two decades to identify new targets for Provincial stewardship and intervention.MethodsAntibiotic prescription information was extracted from PharmaNet, a centralized data system that links all pharmacies with prescriptions dispensed in the community setting. The Medical Service Plan records reimbursement claims submitted by physicians for services provided, including diagnostic codes. Antibiotic prescriptions were extracted from PharmaNet and then matched to the billing system using anonymized patient identifiers. Prescription rates were calculated, and trends were examined by major anatomical therapeutic chemical (ATC) classification.ResultsOur study included 3,564,258 individuals over an 18-year period, with a total of 26,108,576 antibiotic prescriptions issued, for common infections. Overall antibiotic utilization decreased 18% (from 228 to 187 prescriptions per 1000 population) over the course of the study period. This trend was reflected in both Beta-Lactam (-37%) and Macrolide (-50%) antibiotics; two of the most common classes prescribed in the outpatient setting. A significant outlier was the J01X class of Other Antibacterials, which increased by a staggering 218%, by 2018. Further analyses are currently underway to stratify these changes in magnitude by demographic variables to identify specific, new targets for stewardship.Rates of outpatient antibiotic prescriptions, for common infections, per 1000 population, by major ATC class, over time. ConclusionOutpatient antibiotic prescribing has decreased steadily since 2000. These promising results can be ascribed to the various Provincial initiatives to quell the misuse of these medications. However, many of the indications tied to these prescriptions do not warrant the use of antibiotics, and further analyses are necessary to evaluate prescribing quality to fully delineate the state of antibiotic use in BC. Next steps also include comparing BC rates with Ontario, another large province of Canada.Disclosures All Authors: No reported disclosures

Recent Advances in 1,3,5-Triazine Derivatives as Antibacterial Agents

Triazine, one of the nitrogen containing heterocyclic compounds has attracted the considerable interest of researchers due to the vast array of biological properties such as anti-viral, antitumor, anti-convulsant, analgesic, antioxidant, anti-depressant, herbicidal, insecticidal, fungicidal, antibacterial and anti-inflammatory activities offered by it. Various antibacterial agents have been synthesized by researchers to curb bacterial diseases but due to rapid development in drug resistance, tolerance and side effects, there had always been a need for the synthesis of a new class of antibacterial agents that would exhibit improved pharmacological action. Therefore, this review mainly focuses on the various methods for the synthesis of triazine derivatives and their antibacterial activity.

Use of mucolytics in COPD: A Delphi consensus study

BackgroundInternational guidelines recommend mucolytic agents as add-on therapy in selected patients with COPD because they may reduce exacerbations and improve health status. As the evidence varies among mucolytic agents, we used the Delphi method to assess consensus amongst an international panel of COPD experts on mucolytics use in COPD. Methods53 COPD experts from 12 countries were asked to complete an online questionnaire and rate their agreement with 15 statements using a 5-point scale. The mucolytic agents evaluated were carbocysteine, erdosteine and N-acetylcysteine (NAC). Data were collected anonymously and consensus presented using descriptive statistics. ResultsThe 47 respondents reached consensus on the statements. They agreed that regular treatment with mucolytic agents effectively reduces the frequency of exacerbations, reduces the duration of mild-to-moderate exacerbations, and can increase the time to first exacerbation and symptom-free time in COPD patients. Consensus was consistently highest for erdosteine. The experts agreed that all three mucolytics display antioxidant and anti-inflammatory activity. Erdosteine and NAC were thought to improve the efficacy of some classes of antibacterial drugs. All three mucolytics were considered effective for the short-term treatment of symptoms of acute exacerbations when added to other drugs. The panel agreed that approved doses of mucolytic agents have favorable side-effect profiles and can be recommended for regular use in patients with a bronchitic phenotype. ConclusionsConsensus findings support the wider use of mucolytic agents as add-on therapy for COPD. However, the differences in pharmacological actions and clinical effectiveness must be considered when deciding which mucolytic to use.

Inhibitors of β-Lactamases. New Life of β-Lactam Antibiotics.

β-Lactam antibiotics account for about 60% of all produced antibiotics. Due to a high activity and minimal side effects, they are the most commonly used class of antibacterial drugs for the treatment of various infectious diseases of humans and animals, including severe hospital infections. However, the emergence of bacteria resistant to β-lactams has led to the clinical inefficiency of these antibiotics, and as a result, their use in medicine has been limited. The search for new effective ways for overcoming the resistance to β-lactam antibiotics is an essential task. The major mechanism of bacterial resistance is the synthesis of β-lactamases (BLs) that break the antibiotic β-lactam ring. Here, we review specific inhibitors of serine β-lactamases and metallo-β-lactamases and discuss approaches for creating new inhibitors that would prolong the "life" of β-lactams.

Electropolymerizations of two novelEDOT‐BODIPYzincoxide nanocomposites andevaluation of their in vitro antibacterial activities

Boron containing materials as novel classes of antibacterial agents have been widely used in coating or medical applications due to their excellent functionality against microorganisms. In this study, two different boron dipyrromethene (BODIPY)/zinc oxide based P(M1‐co‐Edot)/ZnO and P(M2‐co‐Edot)/ZnO nanocomposite copolymer materials were prepared. The BODIPY/ZnO nanocomposite films were synthesized using potentiostat. ZnO nanoparticles were used to increase the strength and conductivity of the obtained semiconducting materials. Spectroelectrochemical analysis show that the copolymers, P(M1‐co‐Edot)/ZnO and P(M2‐co‐Edot)/ZnO, have electronic band gaps at 1.56 and 2.51 eV and optical band gaps at 2.11 and 2.00 eV, respectively. The synthesized nanocomposite films were characterized by Raman, nuclear magnetic resonance (NMR) and FT‐IR spectroscopies. The optical properties of the synthesized monomers and their nanocomposite copolymers were demonstrated using UV‐Vis and fluorescence spectroscopy. SEM and AFM images show the surface morphologies of nanocomposite copolymer films and surface roughness of P(M1‐co‐Edot)/ZnO and P(M2‐co‐Edot)/ZnO were calculated as Ra = 84.6 nm Rq = 106 nm and 120 nm, respectively. Antibacterial activities of the obtained nanocomposite films prepared in ultrapure water with different concentrations (2.5‐0.25 mg/mL) were discovered against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria by using disc diffusion method. The antibacterial activities of obtained films were found to be higher against Gram negative bacteria compared to that of Gram positives. Obtained results show that synthesized nanocomposites with easy production and nontoxic properties can be used as functional bioengineering materials for antibacterial electrochromical materials.

Distribution of aminoglycoside resistance genes in clinical isolates of Pseudomonas aeruginosa in north of Iran

BackgroundP. aeruginosa is a nosocomial pathogen of global concern due to its hospital-acquired infections and antibacterial resistance. Aminoglycoside is a common treatment alternative for infections caused by this bacterium. This study investigated the distribution of aminoglycoside modifying enzymes (AMEs) and 16S rRNA methylase in P. aeroginosa isolated from Guilan province, Iran. Materials and methodsDuring the eight months of study, 122 isolates of P. aeruginosa were collected from clinical specimens. Three common aminoglycoside susceptibility tests were performed and minimum inhibitory concentration (MIC) was determined using disk diffusion method and broth-microdilution testing. AMEs and 16S rRNA methylase variants in test bacteria were detected by PCR assay. ResultsIn this study, 51 (41.8%) P. aeruginosa isolates were pan aminoglycoside resistant and according to MIC level, 40 (32.8%) isolates showed high levels of resistance. The most prevalent aminoglycoside resistance genes in test isolates were ant(2″)-Ia and aac(6′)-Ib, which were detected in 85% and 71.2% of the resistant isolates, respectively. rmtC and ant(4′)Ia were not detected in any isolates. All high-level aminoglycoside-resistant isolates, multiple modifying enzyme genes, were investigated with 23 different gene combinations comprised of 2–5 AMEs and 16S rRNA methyltransferases. ConclusionHigh-level carriage of different aminoglycoside resistance genes in P. aeruginosa isolates indicates the reduced effectiveness of this class of antibacterials, hence the necessity of producing effective antibacterial agents stable in the presence of these resistance genes.

Phytochemical conjugation as a potential semisynthetic approach toward reactive and reuse of obsolete sulfonamides against pathogenic bacteria.

The emergence and reemergence of multidrug-resistant (MDR) bacteria and mycobacteria in community and hospital periphery have directly enhanced the hospitalization costs, morbidity and mortality, globally. The appearance of MDR pathogens, the currently used antibiotics, remains insufficient, and the development of potent antibacterial(s) is merely slow. Thus, the development of active antibacterials is the call of the day. The sulfonamides class of antibacterials was the most successful synthesized drug in the 19th century. Mechanically, sulfonamides were targeting bacterial folic acid biosynthesis and today, those are obsolete or clinically inactive. Nevertheless, the magic sulfonamide pharmacophore has been used continuously in several mainstream antibacterial, antidiabetic, antiviral drugs. Concomitantly, thousands of phytochemicals with antimicrobial potencies have been recorded and were commanded as alternate antibacterials toward control of MDR pathogens. However, none/very few isolated phytochemicals have gone up to the pure-drug stage due to the lack of the desired drug-likeness values and the required pharmacokinetic properties. Thus, chemical modification of parent drug remains as the versatile approach in antibacterial drug development. Improvement of clinically inactive sulfa drugs with suitable phytochemicals to develop active, low-toxic drug molecules followed by medicinal chemistry could be prudent. This review highlights such "sulfonamide-phytochemical" hybrid drug development research works for utilizing inactive sulfonamides and phytochemicals; the ingenious cost-effective and resource-saving hybrid drug concept could be a new trend in current antibacterial drug discovery to reactive the obsolete antibacterials.

Antibacterial and antibiofilm efficacy of synthetic polymyxin‐mimetic lipopeptides

AbstractThe increasing emergence of multidrug‐resistant bacteria is a huge problem to society providing significant risks to public health. This has been further escalated by a decline in the clinical translation of new antibacterial drug classes since the 1980s. In this article, we describe the synthesis, antibacterial/antibiofilm activity and in vitro toxicity of synthetic low molecular weight lipopeptides mimetics of polymyxin. C12‐KTKCKFLKKC‐NH2 and C14‐KTKCKFLKKC‐NH2 lipopeptides demonstrated activity against both planktonic and biofilm forms of Staphylococcus epidermidis, Staphylococcus aureus, MRSA, Escherichia coli, and Acinetobacter baumannii. Peptide‐outer membrane interaction was studied using lipopolysaccharide neutralization and N‐phenyl‐1‐napthylamine assays. C12‐conjugated peptide significantly neutralized lipopolysaccharide at concentrations lower than minimum inhibitory concentration values against Gram‐negative E coli, by an average of 90% and demonstrated up to double the outer membrane permeabilization ability of 10 mg/mL polymyxin B. Polymyxin‐mimetic lipopeptides have the potential to undergo further in vitro and in vivo study to enable clinical translation and help alleviate the current antimicrobial crisis.

Antibacterial Spiropyrimidinetriones with N-Linked Azole Substituents on a Benzisoxazole Scaffold Targeting DNA Gyrase.

Herein, we report spiropyrimidinetriones (SPTs) incorporating N-linked azole substituents on a benzisoxazole scaffold with improved Gram-positive antibacterial activity relative to previously described analogues. SPTs have an unusual spirocyclic architecture and represent a new antibacterial class of bacterial DNA gyrase and topoisomerase IV inhibitors. They are not cross-resistant to fluoroquinolones and other DNA gyrase/topoisomerase IV inhibitors used clinically. The activity of the SPTs was assessed for DNA gyrase inhibition, and the antibacterial activity across Gram-positive and Gram-negative pathogens with N-linked 1,2,4-triazoles substituted on the 5-position provides the most worthwhile profile. Directed nucleophilic and electrophilic chemistry was developed to vary this 5-position with carbon, nitrogen, or oxygen substituents and explore structure-activity relationships including those around a target binding model. Compounds with favorable pharmacokinetic parameters were identified, and two compounds demonstrated cidality in a mouse model of Staphylococcus aureus infection.

From Antibacterial to Antitumour Agents: A Brief Review on The Chemical and Medicinal Aspects of Sulfonamides.

Sulfonamides have been in clinical use for many years, and the development of bioactive substances containing the sulfonamide subunit has grown steadily in view of their important biological properties such as antibacterial, antifungal, antiparasitic, antioxidant, and antitumour properties. This review addresses the medicinal chemistry aspects of sulfonamides; covering their discovery, the structure- activity relationship and the mechanism of action of the antibacterial sulfonamide class, as well as the physico-chemical and pharmacological properties associated with this class. It also provides an overview of the various biological activities inherent to sulfonamides, reporting research that emphasises the importance of this group in the planning and development of bioactive substances, with a special focus on potential antitumour properties. The synthesis of sulfonamides is considered to be simple and provides a diversity of derivatives from a wide variety of amines and sulfonyl chlorides. The sulfonamide group is a non-classical bioisostere of carboxyl groups, phenolic hydroxyl groups and amide groups. This review highlights that most of the bioactive substances have the sulfonamide group, or a related group such as sulfonylurea, in an orientation towards other functional groups. This structural characteristic was observed in molecules with distinct antibacterial activities, demonstrating a clear structure-activity relationship of sulfonamides. This short review sought to contextualise the discovery of classic antibacterial sulfonamides and their physico-chemical and pharmacological properties. The importance of the sulfonamide subunit in Medicinal Chemistry has been highlighted and emphasised, in order to promote its inclusion in the planning and synthesis of future drugs.

Analogs of nitrofuran antibiotics are potent GroEL/ES inhibitor pro-drugs

In two previous studies, we identified compound 1 as a moderate GroEL/ES inhibitor with weak to moderate antibacterial activity against Gram-positive and Gram-negative bacteria including Bacillus subtilis, methicillin-resistant Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumannii, and SM101 Escherichia coli (which has a compromised lipopolysaccharide biosynthetic pathway making bacteria more permeable to drugs). Extending from those studies, we developed two series of analogs with key substructures resembling those of known antibacterials, nitroxoline (hydroxyquinoline moiety) and nifuroxazide/nitrofurantoin (bis-cyclic-N-acylhydrazone scaffolds). Through biochemical and cell-based assays, we identified potent GroEL/ES inhibitors that selectively blocked E. faecium, S. aureus, and E. coli proliferation with low cytotoxicity to human colon and intestine cells in vitro. Initially, only the hydroxyquinoline-bearing analogs were found to be potent inhibitors in our GroEL/ES-mediated substrate refolding assays; however, subsequent testing in the presence of an E. coli nitroreductase (NfsB) in situ indicated that metabolites of the nitrofuran-bearing analogs were potent GroEL/ES inhibitor pro-drugs. Consequently, this study has identified a new target of nitrofuran-containing drugs, and is the first reported instance of such a unique class of GroEL/ES chaperonin inhibitors. The intriguing results presented herein provide impetus for expanded studies to validate inhibitor mechanisms and optimize this antibacterial class using the respective GroEL/ES chaperonin systems and nitroreductases from E. coli and the ESKAPE bacteria.

1,2,3-Triazole-containing hybrids with potential antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA), as a classic reason for genuine skin and flimsy tissues diseases, is a worldwide general wellbeing risk and has already tormented humanity for a long history, creating a critical need for the development of new classes of antibacterials. 1,2,3-Triazole moiety, readily interact with diverse enzymes and receptors in organisms through weak bond interaction, is among the most common frameworks present in the bioactive molecules. 1,2,3-Triazole derivatives, especially 1,2,3-triazole-containing hybrids, possess broad-spectrum activity against a panel of clinically important bacteria including drug-resistant pathogens, so rational design of 1,2,3-triazole derivatives may open a door for the opportunities on the development of novel anti-MRSA agents. This review is an endeavour to highlight the current scenario of 1,2,3-triazole-containing hybrids with potential anti-MRSA activity, covering articles published between 2010 and 2020.

Exploitation of Pare Topoisomerase IV as Drug Target for the Treatment of Multidrug-Resistant Bacteria: A Review

The antibacterial resistance (ABR) is a growing phenomenon and global threat to mankind. To circumvent the ABR, many approaches have been put forth, but none of them meet the pre-requisites associated with the resistance mechanisms. In this review, we focused on the importance of unexploited enzyme, ParE, a topoisomerase responsible for the bacterial survival. The bacterial topoisomerases maintain the topological state of DNA. The gyrases and topoisomerases IV are validated targets for the antibacterial activity. Both these enzymes are structurally similar and possess high degree conservation in the catalytic domain of the N-terminal region, which make them appealing targets for broad spectrum antibacterial activity. Despite being an attractive target for the development of new antibacterials, there are currently no antibiotics targeting gyrases and topoisomerase (topo) IV in the market. Availability of the high-resolution crystal structure data for ParE made it possible to design new classes of antibacterials. Here, we discuss the importance of targeting topo IV enzyme as it is less prone to bacterial resistance which has been disclosed in the literature.

Exploring Endolysin-Loaded Alginate-Chitosan Nanoparticles as Future Remedy for Staphylococcal Infections.

Endolysins are a novel class of antibacterials with proven efficacy in combating various bacterial infections, in vitro and in vivo. LysMR-5, an endolysin derived from phage MR-5, demonstrated high lytic activity in our laboratory against multidrug-resistant S. aureus (MRSA) and S. epidermidis strains. However, endolysin and proteins in general are associated with instability and short in vivo half-life, consequently limiting their usage as pharmaceutical preparation to treat bacterial infections. Nanoencapsulation of endolysins could help to achieve better therapeutic outcome, by protecting the proteins from degradation, providing sustained release, thus could increase their stability, shelf life, and therapeutic efficacy. Hence, in this study, the feasibility of alginate-chitosan nanoparticles (Alg-Chi NPs) to serve as drug delivery platform for LysMR-5 was evaluated. LysMR-5-loaded nanoparticles were prepared by calcium ion-induced pre-gelation of alginate core and its complexation with chitosan. The formation of nanoparticles was confirmed on the basis of DLS, zeta potential, and electron microscopy imaging. The LysMR-5-loaded nanoparticles presented a hydrodynamic diameter of 276.5 ± 42, a PDI of 0.342 ± 0.02, a zeta potential - 25mV, and an entrapment efficiency of 62 ± 3.1%. The potential ionic interaction between alginate, chitosan, and LysMR-5 was investigated by FT-IR and SEM-EDX analysis. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nano-sized particles with characteristic morphology were seen. Different antibacterial assays and SDS-PAGE analysis showed no change in endolysin's structural integrity and bioactivity after entrapment. A direct antibacterial effect of blank Alg-Chi Nps, showing enhanced bactericidal activity upon LysMR-5 loading, was observed against S. aureus. At physiological pH (7.2), the release profile of LysMR-5 from Alg-Chi NPs showed a biphasic release and followed a non-Fickian release mechanism. The biocompatible nature as revealed by cytocompatibility and hemocompatibility studies endorsed their use as drug delivery system for in vivo studies. Collectively, these results demonstrate the potential of Alg-Chi NPs as nano-delivery vehicle for endolysin LysMR-5 and other therapeutic proteins for their use in various biomedical applications.

Determination of Pharmacokinetic Parameters of a Four-Armed, Guanidinium-Rich Structurally Nanoengineered Antimicrobial Peptide Polymer: A Research Protocol

Introduction: Antibacterial resistance has accentuated the need for the development of novel, efficacious pharmaceuticals. Structurally nanoengineered antimicrobial polypeptide polymers (SNAPPs) have shown promise as a candidate for a new antibacterial pharmaceutical class which may help overcome the problem of antibacterial resistance in humans or animals. Particularly, the SNAPP with a chemical formula (RGRGRGRGRGRG)4K2K-NH2 (4R6G6) has been shown to exhibit negligible hemolysis while retaining low minimal inhibitory concentrations against bacteria. An important consideration in drug development is pharmacokinetic studies, however, there have been no prior pharmacokinetic studies involving SNAPPs. Therefore, the objective of this study is to determine the pharmacokinetic parameters of 4R6G6. Methods: 4R6G6 will be synthesized and purified according to previously reported methods. 4R6G6 will be administered to BALB/c mice intravenously, serial blood samples will be taken from 0-48 hours after SNAPP administration and serum 4R6G6 concentrations will be quantified over time by liquid chromatography mass spectrometry. This information will be used to calculate key pharmacokinetic parameters using Pmetrics. Results: We expect that the half-life of elimination will be on the order of hours and will exceed 3 hours, while the volume of distribution will be equal to the plasma volume of a mouse (1.2 mL/mouse) Discussion: The half-life of elimination of 4R6G6 will influence its desirability as a future drug target. Additionally, the volume of distribution is expected to indicate a distribution into plasma, and can be used to calculate the desired dose for a certain plasma concentration in future studies. Conclusion: Given the expected half-life of elimination on the order of hours, we expect 4R6G6 to be a strong candidate for further translational study in the race to combat antibacterial resistance. Future directions include the quantification of the safety of the drug by determining the therapeutic index in vivo.

A VersaTile-driven platform for rapid hit-to-lead development of engineered lysins.

Health care authorities are calling for new antibacterial therapies to cope with the global emergence of antibiotic-resistant bacteria. Bacteriophage-encoded lysins are a unique class of antibacterials with promising (pre)clinical progress. Custom engineering of lysins allows for the creation of variants against potentially any bacterial pathogen. We here present a high-throughput hit-to-lead development platform for engineered lysins. The platform is driven by VersaTile, a new DNA assembly method for the rapid construction of combinatorial libraries of engineered lysins. We constructed approximately 10,000 lysin variants. Using an iterative screening procedure, we identified a lead variant with high antibacterial activity against Acinetobacter baumannii in human serum and an ex vivo pig burn wound model. This generic platform could offer new opportunities to populate the preclinical pipeline with engineered lysins for diverse (therapeutic) applications.