RESUMO
The prevalence of antimicrobial resistance in Gram-negative bacteria poses a greater challenge due to their intrinsic resistance to many antibiotics. Recently, darobactins have emerged as a novel class of antibiotics originating from previously unexplored Gram-negative bacterial species such as Photorhabdus, Vibrio, Pseudoalteromonas and Yersinia. Darobactins belong to the ribosomally synthesized and post-translationally modified peptide (RiPP) class of antibiotics, exhibiting selective activity against Gram-negative bacteria. They target the ß-barrel assembly machinery (BAM), which is crucial for the maturation and insertion of outer membrane proteins in Gram-negative bacteria. The dar operon in the producer's genome encodes for the synthesis of darobactins, which are characterized by a fused ring system connected via an alkyl-aryl ether linkage (C-O-C) and a C-C cross-link. The enzyme DarE, using the radical S-adenosyl-l-methionine (rSAM), facilitates the formation of these bonds. Biosynthetic manipulation of the darobactin gene cluster, along with its expression in a surrogate host, has enabled access to diverse darobactin analogues with variable antibiotic activities. Recently, two independent research groups successfully achieved the total synthesis of darobactin, employing Larock heteroannulation to construct the bicyclic structure. This paper presents a comprehensive review of darobactins, encompassing their discovery through to the most recent advancements.
Assuntos
Antibacterianos , Antibacterianos/farmacologia , Antibacterianos/química , Bactérias Gram-Negativas/efeitos dos fármacos , Descoberta de Drogas , Família Multigênica , Photorhabdus/genética , Photorhabdus/metabolismo , Testes de Sensibilidade Microbiana , Pseudoalteromonas/genética , Pseudoalteromonas/metabolismoRESUMO
Increasing multidrug resistance in Neisseria gonorrheae is a growing public health crisis. Resistance to the last line therapies, cephalosporins and azithromycin, are of particular concern, fueling the need to discover new treatments. Here, we identified the phosphoglycolipid moenomycin from a screen of microbial natural products against drug-resistant N. gonorrheae as a potent antigonococcal agent. Moenomycin demonstrates excellent activity (MIC = 0.004-0.03 µg/mL) against a variety of multidrug-resistant N. gonorrheae. Importantly, moenomycin, thought to be a Gram-positive specific antibiotic, penetrates the Gram-negative gonococcal outer membrane. Moenomycin causes intracellular accumulation of peptidoglycan precursors, cell blebbing, and rupture of the cell envelope, all consistent with cell wall biosynthesis inhibition. Serial bacterial exposure to moenomycin for 14 days revealed slow development of resistance (MICDay14 = 0.03-0.06 µg/mL), unlike the clinically used drug azithromycin. Our results offer the potential utility of moenomycin as a lead for antigonococcal therapeutic candidates and warrant further investigation.
Assuntos
Bambermicinas , Produtos Biológicos , Antibacterianos/farmacologia , Produtos Biológicos/farmacologia , Peptidoglicano , Extratos VegetaisRESUMO
The rise of bacterial antibiotic resistance coupled with a diminished antibiotic drug pipeline underlines the importance of developing rational strategies to discover new antimicrobials. Microbially derived natural products are the basis for most of the antibiotic arsenal available to modern medicine. Here, we demonstrate a resistance-based approach to identify producers of elfamycins, an under-explored class of natural product antibiotics that target the essential translation factor EF-Tu. Antibiotic producers carry self-resistance genes to avoid suicide. These genes are often found within the same biosynthetic gene cluster (BGC) responsible for making the antibiotic, and we exploited this trait to identify members of the kirromycin class of elfamycin producers. Genome mining of Streptomyces spp. led to the identification of three isolates that harbor kirromycin-resistant EF-Tu (EF-TuKirR) within predicted natural product BGCs. Activity-guided purification on extracts of one of the Streptomyces isolates, which was not known to produce an elfamycin, identified it as a producer of phenelfamycin B, a linear polyketide. Phenelfamycin B demonstrates impressive antibacterial activity (MIC â¼ 1 µg/mL) against multidrug-resistant Neisseria gonorrhoeae, a clinically important Gram negative pathogen. The antigonococcal activity of phenelfamycin was shown to be the result of inhibition of protein biosynthesis by binding to EF-Tu. These results indicate that a resistance-based approach of identifying elfamycin producers is translatable to other antibiotic classes that can identify new and overlooked antibiotics necessary to address the antibiotic crisis.
Assuntos
Antibacterianos , Farmacorresistência Bacteriana , Streptomyces , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , Fator Tu de Elongação de Peptídeos/genética , Fator Tu de Elongação de Peptídeos/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , Streptomyces/genéticaRESUMO
Despite the remarkable advances due to the discovery and development of antimicrobials agents, infectious diseases remain the second leading cause of death worldwide. This fact underlines the importance of developing new therapeutic strategies to address the widespread antibiotic resistance, which is the major contributing factor for clinical failures of the current therapeutics. In a screen for antibiotic adjuvants, we identified a natural product from actinomycetes, venturicidin A (VentA), that potentiates the aminoglycoside antibiotic gentamicin against multidrug-resistant clinical isolates of Staphylococcus, Enterococcus, and Pseudomonas aeruginosa. Furthermore, the combination of gentamicin and VentA was bactericidal and rapidly eradicated methicillin-resistant S. aureus (MRSA). The molecular mechanism of gentamicin potentiation activity is attributed to uncoupling of ATP synthesis by VentA from electron transport presumably by blocking the proton flow through ATP synthase, which results in an elevated concentration of extracellular protons and subsequent anticipated raise in gentamicin uptake. The disruption of the proton flux was characterized by perturbed membrane potential in MRSA. These results demonstrate that inhibition of ATP synthase along with the subsequent membrane dysregulation, as shown here with VentA, complements aminoglycoside antibiotics against MDR bacteria, and that this approach may be employed to combat bacterial resistance.
Assuntos
Complexos de ATP Sintetase/antagonistas & inibidores , Actinobacteria/química , Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Venturicidinas/farmacologia , Complexos de ATP Sintetase/genética , Complexos de ATP Sintetase/metabolismo , Trifosfato de Adenosina/metabolismo , Aminoglicosídeos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/enzimologia , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/genéticaRESUMO
Vancomycin is a standard drug for the treatment of multidrug-resistant Gram-positive bacterial infections. Albeit, development of resistance (VRE, VRSA) and its inefficacy against persistent infections is a demerit. It is also intrinsically inactive against Gram-negative bacteria. Herein, we report a vancomycin derivative, VanQAmC10, that addresses these challenges. VanQAmC10 was rapidly bactericidal against carbapenem-resistant A. baumannii (6 log10 CFU/mL reduction in 6 h), disrupted A. baumannii biofilms, and eradicated their stationary phase cells. In MRSA infected macrophages, the compound reduced the bacterial burden by 1.3 log10 CFU/mL while vancomycin exhibited a static effect. Further investigation indicated that the compound, unlike vancomycin, promoted the intracellular degradative mechanism, autophagy, in mammalian cells, which may have contributed to its intracellular activity. The findings of the work provide new perspectives on the field of glycopeptide antibiotics.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Autofagia/efeitos dos fármacos , Vancomicina/análogos & derivados , Vancomicina/farmacologia , Acinetobacter baumannii/fisiologia , Animais , Antibacterianos/síntese química , Antibacterianos/toxicidade , Biofilmes/efeitos dos fármacos , Feminino , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Vancomicina/toxicidade , Resistência beta-Lactâmica/efeitos dos fármacosRESUMO
In this issue of Cell Chemical Biology, Radlinski et al. (2019) identify Pseudomonas-derived rhamnolipids that potentiate aminoglycoside antibiotics in the eradication of antibiotic-tolerant bacterial phenotypes. Microbial physiological and mechanistic studies indicate that rhamnolipids permeabilize S. aureus membrane and drive the uptake of aminoglycosides that is independent of proton-motive force.
Assuntos
Antibacterianos , Staphylococcus aureus , Aminoglicosídeos , Glicolipídeos , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosaRESUMO
New Delhi metallo-ß-lactamase-1 (NDM-1) is the major contributor to the emergence of carbapenem resistance in Gram-negative pathogens (GNPs) and has caused many clinically available ß-lactam antibiotics to become obsolete. A clinically approved inhibitor of metallo-ß-lactamase (MBL) that could restore the activity of carbapenems against resistant GNPs has not yet been found, making NDM-1 a serious threat to human health. Here, we have rationally developed an inhibitor for the NDM-1 enzyme, which has the ability to penetrate the outer membrane of GNPs and inactivate the enzyme by depleting the metal ion (Zn2+) from the active site. The inhibitor reinstated the activity of meropenem against NDM-1 producing clinical isolates of GNPs like Klebsiella pneumoniae and Escherichia coli. Further, the inhibitor efficiently restored meropenem activity against NDM-1 producing K. pneumoniae in a murine sepsis infection model. These findings demonstrate that a combination of the present inhibitor and meropenem has high potential to be translated clinically to combat carbapenem-resistant GNPs.
Assuntos
Antibacterianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/metabolismo , Meropeném/farmacologia , Vancomicina/farmacologia , beta-Lactamases/metabolismo , Animais , Permeabilidade da Membrana Celular , Sinergismo Farmacológico , Ativação Enzimática/efeitos dos fármacos , Feminino , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Bactérias Gram-Negativas/genética , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/metabolismo , Camundongos , Estrutura Molecular , Vancomicina/análogos & derivados , Vancomicina/síntese química , Resistência beta-Lactâmica , beta-Lactamases/genéticaRESUMO
Cell wall biosynthesis inhibitors (CBIs) have historically been one of the most effective classes of antibiotics. They are the most extensively used class of antibiotics and their importance is exemplified by the ß-lactams and glycopeptide antibiotics. However, this class of antibiotics has not received impunity from resistance development. In the wake of this predicament, this review presents the progress of CBIs, especially glycopeptide derivatives as antibiotics to confront antibacterial resistance. The various strategies used for the development of CBIs, their clinical status and possible directions in which this field can evolve have also been discussed.
RESUMO
The emergence of drug resistance along with a declining pipeline of clinically useful antibiotics has made it vital to develop more effective antimicrobial therapeutics, particularly against difficult-to-treat Gram-negative pathogens (GNPs). Many antibacterial agents, including glycopeptide antibiotics such as vancomycin, are inherently inactive toward GNPs because of their inability to cross the outer membrane of these pathogens. Here, we demonstrate, for the first time, lipophilic cationic (permanent positive charge) vancomycin analogues were able to permeabilize the outer membrane of GNPs and overcome the inherent resistance of GNPs toward glycopeptides. Unlike vancomycin, these analogues were shown to have a high activity against a variety of multidrug-resistant clinical isolates such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. In the murine model of carbapenem-resistant A. baumannii infection, the optimized compound showed potent activity with no observed toxicity. The notable activity of these compounds is attributed to the incorporation of new membrane disruption mechanisms (cytoplasmic membrane depolarization along with outer and inner (cytoplasmic) membrane permeabilization) into vancomycin. Therefore, our results indicate the potential of the present vancomycin analogues to be used against drug-resistant GNPs, thus strengthening the antibiotic arsenal for combating Gram-negative bacterial infections.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/microbiologia , Vancomicina/farmacologia , Acinetobacter baumannii/efeitos dos fármacos , Animais , Membrana Celular/efeitos dos fármacos , Membrana Celular/microbiologia , Modelos Animais de Doenças , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Relação Estrutura-Atividade , Vancomicina/análogos & derivadosRESUMO
Staphylococcus aureus is a facultative intracellular pathogen and there are limited options for the treatment of severe intracellular bacterial infections. The membrane-active glycopeptide antibiotic Van-QC8 is a permanent positively charged lipophilic vancomycin analogue that demonstrates high activity against clinically relevant drug-resistant Gram-positive bacteria both in vitro and in vivo. In this study, the intracellular activity of Van-QC8 was evaluated against meticillin-resistant S. aureus (MRSA) infection in RAW macrophages. Furthermore, the mechanism of intracellular uptake of Van-QC8 was investigated. Van-QC8 showed time- and concentration-dependent bactericidal activity against intracellular MRSA. Van-QC8 displayed significantly higher intracellular activity compared with vancomycin and linezolid. Cellular uptake of Van-QC8 was found to be through clathrin-dependent and -independent and caveolin-dependent and -independent endocytic pathways. The findings of this study suggest that Van-QC8 could be translated clinically for the treatment of intracellular infections due to MRSA.
Assuntos
Antibacterianos/farmacologia , Glicopeptídeos/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Vancomicina/análogos & derivados , Animais , Camundongos , Células RAW 264.7RESUMO
Vancomycin, the drug of last resort for Gram-positive bacterial infections, has also been rendered ineffective by the emergence of resistance in such bacteria. To combat the threat of vancomycin-resistant bacteria (VRB), we report the development of a dipicolyl-vancomycin conjugate (Dipi-van), which leads to enhanced inhibition of cell-wall biosynthesis in VRB and displays inâ vitro activity that is more than two orders of magnitude higher than that of vancomycin. Conjugation of the dipicolyl moiety, which is a zinc-binding ligand, endowed the parent drug with the ability to bind to pyrophosphate groups of cell-wall lipids while maintaining the inherent binding affinity for pentapeptide termini of cell-wall precursors. Furthermore, no detectable resistance was observed after several serial passages, and the compound reduced the bacterial burden by a factor of 5â logs at 12â mg kg(-1) in a murine model of VRB kidney infection. The findings presented in this report stress the potential of our strategy to combat VRB infections.
Assuntos
Antibacterianos/química , Difosfatos/química , Vancomicina/análogos & derivados , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Diaminas/química , Eritrócitos/citologia , Eritrócitos/efeitos dos fármacos , Eritrócitos/metabolismo , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/microbiologia , Infecções por Bactérias Gram-Positivas/veterinária , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Vancomicina/farmacologia , Vancomicina/uso terapêutico , Resistência a Vancomicina/efeitos dos fármacos , Zinco/químicaRESUMO
Antibiotic-resistant superbugs such as vancomycin-resistant Enterococci (VRE) and Staphylococci have become a major global health hazard. To address this issue, we synthesized vancomycin aglycon dimers to systematically probe the impact of a linker on biological activity. A dimer having a pendant lipophilic moiety in the linker showed â¼300-fold more activity than vancomycin against VRE. The high activity of the compound is attributed to its enhanced binding affinity to target peptides which resulted in improved peptidoglycan (cell wall) biosynthesis inhibition. Therefore, our studies suggest that these compounds, prepared by using facile synthetic methodology, can be used to combat vancomycin-resistant bacterial infections.
Assuntos
Antibacterianos/química , Bactérias/efeitos dos fármacos , Doxorrubicina/análogos & derivados , Farmacorresistência Bacteriana/efeitos dos fármacos , Vancomicina/química , Antibacterianos/farmacologia , Dimerização , Doxorrubicina/química , Lipídeos/química , Testes de Sensibilidade Microbiana , SolubilidadeRESUMO
Resistance to glycopeptide antibiotics, the drugs of choice for life-threatening bacterial infections, is on the rise. In order to counter the threat of glycopeptide-resistant bacteria, we report development of a new class of semi-synthetic glycopeptide antibiotics, which not only target the bacterial membrane but also display enhanced inhibition of cell-wall biosynthesis through increased binding affinity to their target peptides. The combined effect of these two mechanisms resulted in improved inâ vitro activity of two to three orders of magnitude over vancomycin and no propensity to trigger drug resistance in bacteria. In murine model of kidney infection, the optimized compound was able to bring bacterial burden down by about 6 logs at 12â mg kg(-1) with no observed toxicity. The results furnished in this report emphasize the potential of this class of compounds as future antibiotics for drug-resistant Gram-positive infections.
Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Glicopeptídeos/farmacologia , Resistência a Vancomicina/efeitos dos fármacos , Animais , Antibacterianos/síntese química , Antibacterianos/química , Bactérias/citologia , Membrana Celular/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Glicopeptídeos/síntese química , Glicopeptídeos/química , Camundongos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade , Vancomicina/farmacologiaRESUMO
Infections caused by vancomycin-intermediate Staphylococcus aureus (VISA) are associated with high rates of vancomycin treatment failure. The lipophilic vancomycin-carbohydrate conjugate YV4465 is a new glycopeptide antibiotic that is active against a variety of clinically relevant multidrug-resistant Gram-positive pathogens in vitro. YV4465 was 50- and 1000-fold more effective than vancomycin against VISA and vancomycin-resistant enterococci, respectively. This study evaluated the in vivo efficacy against VISA as well as the pharmacokinetics and toxicology of YV4465. A neutropenic mouse thigh infection model was used for the determination of efficacy and pharmacodynamic properties against VISA. YV4465 produced a dose-dependent reduction in VISA titres in thigh muscle; bacterial titres were reduced by up to ca. 2log(10)CFU/g from the pre-treatment titre at a dosage of 8 mg/kg. Single-dose pharmacokinetic studies demonstrated an increase in drug exposure to the animal following linear kinetics with a prolonged half-life (t(1/2)) compared with vancomycin. The peak plasma concentration (C(max)) following an intravenous dose of 12 mg/kg was 703 µg/mL. Acute toxicology studies revealed that YV4465 did not cause any significant alterations in biochemical parameters related to major organs such as the liver and kidneys at its pharmacodynamic endpoint (>ED(2-log kill)). These studies demonstrate that YV4465 has the potential to be developed as a next-generation glycopeptide antibiotic for the treatment of infections caused by VISA.
Assuntos
Antibacterianos/administração & dosagem , Antibacterianos/farmacocinética , Glicopeptídeos/administração & dosagem , Glicopeptídeos/farmacocinética , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Resistência a Vancomicina , Administração Intravenosa , Animais , Carga Bacteriana , Modelos Animais de Doenças , Feminino , Camundongos , Plasma/química , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/isolamento & purificação , Coxa da Perna/microbiologia , Resultado do TratamentoRESUMO
Treating bacterial biofilms with conventional antibiotics is limited due to ineffectiveness of the drugs and higher propensity to develop bacterial resistance. Development of new classes of antibacterial therapeutics with alternative mechanisms of action has become imperative. Herein, we report the design, synthesis, and biological evaluations of novel membrane-active small molecules featuring two positive charges, four nonpeptidic amide groups, and variable hydrophobic/hydrophilic (amphiphilic) character. The biocides synthesized via a facile methodology not only displayed good antibacterial activity against wild-type bacteria but also showed high activity against various drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and ß-lactam-resistant Klebsiella pneumoniae. Further, these biocides not only inhibited the formation of biofilms but also disrupted the established S. aureus and E. coli biofilms. The membrane-active biocides hindered the propensity to develop bacterial resistance. Moreover, the biocides showed negligible toxicity against mammalian cells and thus bear potential to be used as therapeutic agents.
Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia , Antibacterianos/toxicidade , Bactérias/citologia , Bactérias/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Células HEK293 , Hemólise/efeitos dos fármacos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/metabolismo , Cinética , Potenciais da Membrana/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Permeabilidade/efeitos dos fármacos , Potássio/metabolismo , Bibliotecas de Moléculas Pequenas/toxicidade , Relação Estrutura-AtividadeRESUMO
Gram-negative 'superbugs' such as New Delhi metallo-beta-lactamase-1 (blaNDM-1) producing pathogens have become world's major public health threats. Development of molecular strategies that can rehabilitate the 'old antibiotics' and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMs)that restore the antibacterial efficacy (enhancement by >80-1250 fold) of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates.Organismic studies showed that bacteria had an increased and faster uptake of tetracyclinein the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover,bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs.
Assuntos
Membrana Celular/metabolismo , Farmacorresistência Bacteriana/efeitos dos fármacos , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Klebsiella/tratamento farmacológico , Tetraciclina/administração & dosagem , beta-Lactamases/metabolismo , Animais , Antibacterianos/administração & dosagem , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/isolamento & purificação , CamundongosRESUMO
The membrane-active glycopeptide antibiotic YV11455 is a lipophilic cationic vancomycin analogue that demonstrates rapid and concentration-dependent killing of clinically relevant multidrug-resistant (MDR) Gram-positive bacteria in vitro. YV11455 was 2-fold and 54-270-fold more effective than vancomycin against clinical isolates of vancomycin-sensitive and vancomycin-resistant bacteria, respectively. In this study, the in vivo efficacy, pharmacodynamics, pharmacokinetics and acute toxicology of YV11455 were investigated. In vivo activity and pharmacodynamics were determined in the neutropenic mouse thigh infection model against meticillin-resistant Staphylococcus aureus (MRSA). YV11455 produced dose-dependent reductions in MRSA titres in thigh muscle. When administered intravenously, the 50% effective dose (ED(50)) for YV11455 against MRSA was found to be 3.3 mg/kg body weight, and titres were reduced by up to ca. 3log(10)CFU/g from pre-treatment values at a dosage of 12 mg/kg with single treatment. Single-dose pharmacokinetic studies demonstrated linear kinetics and a prolonged half-life, with an increase in drug exposure (area under the concentration-time curve) compared with vancomycin. The peak plasma concentration following an intravenous dose of 12 mg/kg was 543.5 µg/mL. Acute toxicology studies revealed that YV11455 did not cause any significant alterations in biochemical parameters or histological pictures related to major organs such as the liver and kidney at its pharmacodynamic endpoint (ED(3-log kill)). These findings collectively suggest that YV11455 could be used clinically for the treatment of infections caused by MDR Gram-positive bacteria.
Assuntos
Antibacterianos/farmacologia , Antibacterianos/farmacocinética , Glicopeptídeos/farmacologia , Glicopeptídeos/farmacocinética , Infecções Estafilocócicas/tratamento farmacológico , Vancomicina/farmacologia , Vancomicina/farmacocinética , Animais , Antibacterianos/administração & dosagem , Antibacterianos/efeitos adversos , Carga Bacteriana , Modelos Animais de Doenças , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/patologia , Feminino , Glicopeptídeos/administração & dosagem , Glicopeptídeos/efeitos adversos , Testes de Função Renal , Testes de Função Hepática , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Camundongos , Músculos/microbiologia , Infecções Estafilocócicas/microbiologia , Vancomicina/administração & dosagem , Vancomicina/efeitos adversosRESUMO
Gram-negative 'superbugs' such as New Delhi metallo-beta-lactamase-1 (blaNDM-1) producing pathogens have become world's major public health threats. Development of molecular strategies that can rehabilitate the 'old antibiotics' and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMs) that restore the antibacterial efficacy (enhancement by >80-1250 fold) of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates. Organismic studies showed that bacteria had an increased and faster uptake of tetracycline in the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover, bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs.
Assuntos
Sinergismo Farmacológico , Infecções por Klebsiella/tratamento farmacológico , Maleimidas/administração & dosagem , Tetraciclina/administração & dosagem , Animais , Membrana Celular/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Maleimidas/química , Potenciais da Membrana/efeitos dos fármacos , Camundongos , beta-Lactamases/metabolismoRESUMO
Microbial attachment and subsequent colonization onto surfaces lead to the spread of deadly community-acquired and hospital-acquired (nosocomial) infections. Noncovalent immobilization of water insoluble and organo-soluble cationic polymers onto a surface is a facile approach to prevent microbial contamination. In the present study, we described the synthesis of water insoluble and organo-soluble polymeric materials and demonstrated their structure-activity relationship against various human pathogenic bacteria including drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and beta lactam-resistant Klebsiella pneumoniae as well as pathogenic fungi such as Candida spp. and Cryptococcus spp. The polymer coated surfaces completely inactivated both bacteria and fungi upon contact (5 log reduction with respect to control). Linear polymers were more active and found to have a higher killing rate than the branched polymers. The polymer coated surfaces also exhibited significant activity in various complex mammalian fluids such as serum, plasma, and blood and showed negligible hemolysis at an amount much higher than minimum inhibitory amounts (MIAs). These polymers were found to have excellent compatibility with other medically relevant polymers (polylactic acid, PLA) and commercial paint. The cationic hydrophobic polymer coatings disrupted the lipid membrane of both bacteria and fungi and thus showed a membrane-active mode of action. Further, bacteria did not develop resistance against these membrane-active polymers in sharp contrast to conventional antibiotics and lipopeptides, thus the polymers hold great promise to be used as coating materials for developing permanent antimicrobial paint.
Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Antifúngicos/síntese química , Antifúngicos/farmacologia , Membrana Celular/efeitos dos fármacos , Pintura/análise , Polímeros/síntese química , Polímeros/farmacologia , Antibacterianos/química , Antifúngicos/química , Bactérias/efeitos dos fármacos , Infecção Hospitalar/microbiologia , Humanos , Pintura/microbiologia , Polímeros/químicaRESUMO
Vancomycin, a glycopeptide antibiotic, has long been a drug of choice for life-threatening Gram-positive bacterial infections. Vancomycin confers its antibacterial activity by inhibiting bacterial cell wall biosynthesis. However, over the time, vancomycin has also been rendered ineffective by vancomycin-resistant bacteria (VRB). These bacteria developed resistance to it by alteration of cell wall precursor from D-Ala-D-Ala to D-Ala-D-Lac (vancomycin-resistant Enterococci, VRE), which leads to manifold reduction in the binding constant and results in the loss of antibacterial activity. Herein, we report various vancomycin-sugar analogs, based on a simple design rationale, which exhibit increased binding affinity to VRB, thereby resensitizing VRB to vancomycin. Optimized vancomycin-sugar conjugate exhibited 150-fold increase in affinity for N,N'-diacetyl-Lys-D-Ala-D-Lac compared with vancomycin. This improved binding affinity was also reflected in its antibacterial activity, wherein the MIC value was brought down from 750 to 36 µM against VRE (VanA phenotype). To further sensitize against VRE, we appended lipophilic alkyl chain to optimized vancomycin-sugar conjugate. This lipophilic-vancomycin-sugar conjugate was >1000-fold (MIC=0.7 µM) and 250-fold (MIC=1 µM) more effective against VanA and VanB strains of VRE, respectively, compared with vancomycin. Therefore, this synthetically simple approach could lead to the development of new generation of glycopeptide antibiotics, which can be clinically used to tackle VRB infections.