RESUMO
Metallo-ß-lactamases (MBLs), such as New Delhi metallo-ß-lactamase (NDM-1) have spread world-wide and present a serious threat. Expression of MBLs confers resistance in Gram-negative bacteria to all classes of ß-lactam antibiotics, with the exception of monobactams, which are intrinsically stable to MBLs. However, existing first generation monobactam drugs like aztreonam have limited clinical utility against MBL-expressing strains because they are impacted by serine ß-lactamases (SBLs), which are often co-expressed in clinical isolates. Here, we optimized novel monobactams for stability against SBLs, which led to the identification of LYS228 (compound 31). LYS228 is potent in the presence of all classes of ß-lactamases and shows potent activity against carbapenem-resistant isolates of Enterobacteriaceae (CRE).
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Enterobacteriáceas Resistentes a Carbapenêmicos/efeitos dos fármacos , Monobactamas/farmacologia , Resistência beta-Lactâmica/efeitos dos fármacos , beta-Lactamases/metabolismo , Animais , Antibacterianos/efeitos adversos , Antibacterianos/química , Antibacterianos/metabolismo , Aztreonam/farmacologia , Células CHO , Cricetulus , Estabilidade de Medicamentos , Escherichia coli/efeitos dos fármacos , Feminino , Humanos , Meropeném , Camundongos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Monobactamas/efeitos adversos , Monobactamas/química , Monobactamas/metabolismo , Pseudomonas aeruginosa/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Convulsões/induzido quimicamente , Relação Estrutura-Atividade , Tienamicinas/farmacologiaRESUMO
Carbapenem-resistant Acinetobacter baumannii infections have limited treatment options. Synthesis, transport and placement of lipopolysaccharide or lipooligosaccharide (LOS) in the outer membrane of Gram-negative bacteria are important for bacterial virulence and survival. Here we describe the cerastecins, inhibitors of the A. baumannii transporter MsbA, an LOS flippase. These molecules are potent and bactericidal against A. baumannii, including clinical carbapenem-resistant Acinetobacter baumannii isolates. Using cryo-electron microscopy and biochemical analysis, we show that the cerastecins adopt a serpentine configuration in the central vault of the MsbA dimer, stalling the enzyme and uncoupling ATP hydrolysis from substrate flipping. A derivative with optimized potency and pharmacokinetic properties showed efficacy in murine models of bloodstream or pulmonary A. baumannii infection. While resistance development is inevitable, targeting a clinically unexploited mechanism avoids existing antibiotic resistance mechanisms. Although clinical validation of LOS transport remains undetermined, the cerastecins may open a path to narrow-spectrum treatment modalities for important nosocomial infections.
Assuntos
Infecções por Acinetobacter , Acinetobacter baumannii , Antibacterianos , Proteínas de Bactérias , Lipopolissacarídeos , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/metabolismo , Lipopolissacarídeos/metabolismo , Animais , Infecções por Acinetobacter/microbiologia , Infecções por Acinetobacter/tratamento farmacológico , Camundongos , Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Transporte Biológico , Testes de Sensibilidade Microbiana , Humanos , Microscopia Crioeletrônica , Carbapenêmicos/farmacologia , Carbapenêmicos/metabolismo , Modelos Animais de Doenças , Feminino , Transportadores de Cassetes de Ligação de ATPRESUMO
Acinetobacter baumannii, a commonly multidrug-resistant Gram-negative bacterium responsible for large numbers of bloodstream and lung infections worldwide, is increasingly difficult to treat and constitutes a growing threat to human health. Structurally novel antibacterial chemical matter that can evade existing resistance mechanisms is essential for addressing this critical medical need. Herein, we describe our efforts to inhibit the essential A. baumannii lipooligosaccharide (LOS) ATP-binding cassette (ABC) transporter MsbA. An unexpected impurity from a phenotypic screening was optimized as a series of dimeric compounds, culminating with 1 (cerastecin D), which exhibited antibacterial activity in the presence of human serum and a pharmacokinetic profile sufficient to achieve efficacy against A. baumannii in murine septicemia and lung infection models.
RESUMO
LFF571 is a novel semisynthetic thiopeptide antibiotic with potent activity against a variety of Gram-positive pathogens, including Clostridium difficile. In vivo efficacy of LFF571 was compared to vancomycin in a hamster model of C. difficile infection (CDI). Infection was induced in Golden Syrian hamsters using a toxigenic strain of C. difficile. Treatment started 24 h postinfection and consisted of saline, vancomycin, or LFF571. Cox regression was used to analyze survival data from a cohort of animals evaluated across seven serial experimental groups treated with vancomycin at 20 mg/kg, LFF571 at 5 mg/kg, or vehicle alone. Survival was right censored; animals were not observed beyond day 21. At death or end of study, cecal contents were tested for C. difficile toxins A and B. In summary, the data showed that 5 mg/kg LFF571 decreased the risk of death by 79% (P < 0.0001) and 69% (P = 0.0022) compared with saline and 20 mg/kg vancomycin, respectively. Further analysis of the pooled data indicated that the survival benefit of LFF571 treatment at 5 mg/kg compared to vancomycin at 20 mg/kg was due primarily to a decrease in the risk of recurrence after end of treatment. Animals successfully treated with LFF571 or vancomycin had no detectable C. difficile toxin. Overall, LFF571 was more efficacious at the end of the study, at a lower dose, and with fewer recurrences, than vancomycin in the hamster model of CDI. LFF571 is being assessed in humans for safety and efficacy in the treatment of C. difficile infections.
Assuntos
Antibacterianos/uso terapêutico , Clostridioides difficile/efeitos dos fármacos , Enterocolite Pseudomembranosa/tratamento farmacológico , Tiazóis/uso terapêutico , Vancomicina/uso terapêutico , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/análise , Toxinas Bacterianas/análise , Cricetinae , Enterotoxinas/análise , Masculino , Mesocricetus , Recidiva , Tiazóis/farmacologia , Vancomicina/farmacologiaRESUMO
Herein, we describe the discovery and optimization of a novel series that inhibits bacterial DNA gyrase and topoisomerase IV via binding to, and stabilization of, DNA cleavage complexes. Optimization of this series led to the identification of compound 25, which has potent activity against Gram-positive bacteria, a favorable in vitro safety profile, and excellent in vivo pharmacokinetic properties. Compound 25 was found to be efficacious against fluoroquinolone-sensitive Staphylococcus aureus infection in a mouse thigh model at lower doses than moxifloxacin. An X-ray crystal structure of the ternary complex formed by topoisomerase IV from Klebsiella pneumoniae, compound 25, and cleaved DNA indicates that this compound does not engage in a water-metal ion bridge interaction and forms no direct contacts with residues in the quinolone resistance determining region (QRDR). This suggests a structural basis for the reduced impact of QRDR mutations on antibacterial activity of 25 compared to fluoroquinolones.
Assuntos
Antibacterianos/farmacologia , DNA Girase/metabolismo , DNA Topoisomerase IV/antagonistas & inibidores , Desenho de Fármacos , Fluoroquinolonas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Inibidores da Topoisomerase II/farmacologia , Animais , Antibacterianos/química , Farmacorresistência Bacteriana/efeitos dos fármacos , Camundongos , Inibidores da Topoisomerase II/químicaRESUMO
Transcriptional profiling data accumulated in recent years for the clinically relevant pathogen Staphylococcus aureus have established a cell wall stress stimulon, which comprises a coordinately regulated set of genes that are upregulated in response to blockage of cell wall biogenesis. In particular, the expression of cwrA (SA2343, N315 notation), which encodes a putative 63 amino acid polypeptide of unknown biological function, increases over 100-fold in response to cell wall inhibition. Herein, we seek to understand the biological role that this gene plays in S. aureus. cwrA was found to be robustly induced by all cell wall-targeting antibiotics tested - vancomycin, oxacillin, penicillin G, phosphomycin, imipenem, hymeglusin and bacitracin - but not by antibiotics with other mechanisms of action, including ciprofloxacin, erythromycin, chloramphenicol, triclosan, rifampicin, novobiocin and carbonyl cyanide 3-chlorophenylhydrazone. Although a DeltacwrA S. aureus strain had no appreciable shift in MICs for cell wall-targeting antibiotics, the knockout was shown to have reduced cell wall integrity in a variety of other assays. Additionally, the gene was shown to be important for virulence in a mouse sepsis model of infection.
Assuntos
Proteínas de Bactérias/fisiologia , Parede Celular/fisiologia , Staphylococcus aureus/genética , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Bacteriólise , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Perfilação da Expressão Gênica , Técnicas de Inativação de Genes , Genes Reporter , Lisostafina/farmacologia , Camundongos , Testes de Sensibilidade Microbiana , Sepse/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia , Staphylococcus aureus/ultraestrutura , VirulênciaRESUMO
Since their discovery over 5 decades ago, quinolone antibiotics have found enormous success as broad spectrum agents that exert their activity through dual inhibition of bacterial DNA gyrase and topoisomerase IV. Increasing rates of resistance, driven largely by target-based mutations in the GyrA/ParC quinolone resistance determining region, have eroded the utility and threaten the future use of this vital class of antibiotics. Herein we describe the discovery and optimization of a series of 4-(aminomethyl)quinolin-2(1H)-ones, exemplified by 34, that inhibit bacterial DNA gyrase and topoisomerase IV and display potent activity against ciprofloxacin-resistant Gram-negative pathogens. X-ray crystallography reveals that 34 occupies the classical quinolone binding site in the topoisomerase IV-DNA cleavage complex but does not form significant contacts with residues in the quinolone resistance determining region.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Fluoroquinolonas/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Inibidores da Topoisomerase II/farmacologia , Antibacterianos/síntese química , Antibacterianos/metabolismo , Antibacterianos/toxicidade , Sítios de Ligação , Linhagem Celular Tumoral , DNA Girase/metabolismo , DNA Topoisomerase IV/antagonistas & inibidores , DNA Topoisomerase IV/química , Fluoroquinolonas/síntese química , Fluoroquinolonas/metabolismo , Fluoroquinolonas/toxicidade , Bactérias Gram-Negativas/enzimologia , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade , Inibidores da Topoisomerase II/síntese química , Inibidores da Topoisomerase II/metabolismo , Inibidores da Topoisomerase II/toxicidadeRESUMO
This report summarizes the identification and synthesis of novel LpxC inhibitors aided by computational methods that leveraged numerous crystal structures. This effort led to the identification of oxazolidinone and isoxazoline inhibitors with potent in vitro activity against P. aeruginosa and other Gram-negative bacteria. Representative compound 13f demonstrated efficacy against P. aeruginosa in a mouse neutropenic thigh infection model. The antibacterial activity against K. pneumoniae could be potentiated by Gram-positive antibiotics rifampicin (RIF) and vancomycin (VAN) in both in vitro and in vivo models.
Assuntos
Amidoidrolases/antagonistas & inibidores , Isoxazóis/química , Isoxazóis/farmacologia , Oxazolidinonas/química , Oxazolidinonas/farmacologia , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Camundongos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Conformação MolecularRESUMO
Over the past several decades, the frequency of antibacterial resistance in hospitals, including multidrug resistance (MDR) and its association with serious infectious diseases, has increased at alarming rates. Pseudomonas aeruginosa is a leading cause of nosocomial infections, and resistance to virtually all approved antibacterial agents is emerging in this pathogen. To address the need for new agents to treat MDR P. aeruginosa, we focused on inhibiting the first committed step in the biosynthesis of lipid A, the deacetylation of uridyldiphospho-3-O-(R-hydroxydecanoyl)-N-acetylglucosamine by the enzyme LpxC. We approached this through the design, synthesis, and biological evaluation of novel hydroxamic acid LpxC inhibitors, exemplified by 1, where cytotoxicity against mammalian cell lines was reduced, solubility and plasma-protein binding were improved while retaining potent anti-pseudomonal activity in vitro and in vivo.
Assuntos
Amidoidrolases/antagonistas & inibidores , Antibacterianos/química , Antibacterianos/farmacologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Amidoidrolases/química , Animais , Antibacterianos/síntese química , Técnicas de Química Sintética , Cristalografia por Raios X , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos/métodos , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Inibidores Enzimáticos/síntese química , Feminino , Células Hep G2/efeitos dos fármacos , Humanos , Células K562/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/enzimologia , Relação Estrutura-AtividadeRESUMO
Synthetic studies of the antimicrobial secondary metabolite thiomuracin A (1) provided access to analogues in the Northern region (C2-C10). Selective hydrolysis of the C10 amide of lead compound 2 and subsequent derivatization led to novel carbon- and nitrogen-linked analogues (e.g., 3) which improved antibacterial potency across a panel of Gram-positive organisms. In addition, congeners with improved physicochemical properties were identified which proved efficacious in murine sepsis and hamster C. difficile models of disease. Optimal efficacy in the hamster model of C. difficile was achieved with compounds that possessed both potent antibacterial activity and high aqueous solubility.
Assuntos
Antibacterianos/farmacologia , Clostridioides difficile/efeitos dos fármacos , Infecções por Clostridium/tratamento farmacológico , Peptídeos Cíclicos/farmacologia , Tiazóis/farmacologia , Animais , Antibacterianos/síntese química , Antibacterianos/química , Cricetinae , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Camundongos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Peptídeos Cíclicos/síntese química , Peptídeos Cíclicos/química , Solubilidade , Relação Estrutura-Atividade , Tiazóis/síntese química , Tiazóis/químicaRESUMO
Clostridium difficile (C. difficile) is a Gram positive, anaerobic bacterium that infects the lumen of the large intestine and produces toxins. This results in a range of syndromes from mild diarrhea to severe toxic megacolon and death. Alarmingly, the prevalence and severity of C. difficile infection are increasing; thus, associated morbidity and mortality rates are rising. 4-Aminothiazolyl analogues of the antibiotic natural product GE2270 A (1) were designed, synthesized, and optimized for the treatment of C. difficile infection. The medicinal chemistry effort focused on enhancing aqueous solubility relative to that of the natural product and previous development candidates (2, 3) and improving antibacterial activity. Structure-activity relationships, cocrystallographic interactions, pharmacokinetics, and efficacy in animal models of infection were characterized. These studies identified a series of dicarboxylic acid derivatives, which enhanced solubility/efficacy profile by several orders of magnitude compared to previously studied compounds and led to the selection of LFF571 (4) as an investigational new drug for treating C. difficile infection.
Assuntos
Antibacterianos/síntese química , Clostridioides difficile/efeitos dos fármacos , Enterocolite Pseudomembranosa/tratamento farmacológico , Tiazóis/síntese química , Animais , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Cricetinae , Cristalografia por Raios X , Enterococcus/efeitos dos fármacos , Proteínas de Escherichia coli/antagonistas & inibidores , Proteínas de Escherichia coli/química , Feminino , Masculino , Mesocricetus , Camundongos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Fator Tu de Elongação de Peptídeos/antagonistas & inibidores , Fator Tu de Elongação de Peptídeos/química , Ratos , Ratos Sprague-Dawley , Solubilidade , Staphylococcus aureus/efeitos dos fármacos , Streptococcus pyogenes/efeitos dos fármacos , Relação Estrutura-Atividade , Tiazóis/farmacocinética , ÁguaRESUMO
MarA, SoxS and Rob are transcription factors belonging to the AraC family. While these proteins have been associated historically with control of multiple antibiotic resistance, and tolerance to oxidative stress agents and organic solvents, only a paucity of experimental data support a role in regulating virulence. Clinical Escherichia coli isolates, and isogenic strains lacking marA, soxS and rob, were studied in a murine model of ascending pyelonephritis, which is a clinically relevant model of urinary tract infection. Organisms lacking all three transcription factors (triple knockouts) were significantly less virulent than parental strains, and complementation studies demonstrated that the addition of marA, soxS and rob individually restored wild-type virulence in the triple-knockout strain. Deletion of soxS or rob alone was more detrimental than the removal of marA. Thus, all three proteins contribute to virulence in vivo.