RESUMEN
There is an increasingly urgent and unmet medical need for novel antibiotic drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. Novel bacterial type II topoisomerase inhibitors (NBTIs) are of high interest due to limited cross-resistance with fluoroquinolones, however analogues with Gram-negative activity often suffer from hERG channel inhibition. A novel series of bicyclic-oxazolidinone inhibitors of bacterial type II topoisomerase were identified which display potent broad-spectrum anti-bacterial activity, including against MDR strains, along with an encouraging in vitro safety profile. In vivo proof of concept was achieved in a A. baumannii mouse thigh infection model.
Asunto(s)
Oxazolidinonas , Inhibidores de Topoisomerasa , Animales , Antibacterianos/farmacología , Girasa de ADN/metabolismo , Fluoroquinolonas/farmacología , Ratones , Pruebas de Sensibilidad Microbiana , Oxazolidinonas/farmacología , Relación Estructura-Actividad , Inhibidores de Topoisomerasa II/farmacología , Inhibidores de Topoisomerasa/farmacologíaRESUMEN
OBJECTIVES: To evaluate the efficacy of two novel compounds against mycobacteria and determine the molecular basis of their action on DNA gyrase using structural and mechanistic approaches. METHODS: Redx03863 and Redx04739 were tested in antibacterial assays, and also against their target, DNA gyrase, using DNA supercoiling and ATPase assays. X-ray crystallography was used to determine the structure of the gyrase B protein ATPase sub-domain from Mycobacterium smegmatis complexed with the aminocoumarin drug novobiocin, and structures of the same domain from Mycobacterium thermoresistibile complexed with novobiocin, and also with Redx03863. RESULTS: Both compounds, Redx03863 and Redx04739, were active against selected Gram-positive and Gram-negative species, with Redx03863 being the more potent, and Redx04739 showing selectivity against M. smegmatis. Both compounds were potent inhibitors of the supercoiling and ATPase reactions of DNA gyrase, but did not appreciably affect the ATP-independent relaxation reaction. The structure of Redx03863 bound to the gyrase B protein ATPase sub-domain from M. thermoresistibile shows that it binds at a site adjacent to the ATP- and novobiocin-binding sites. We found that most of the mutations that we made in the Redx03863-binding pocket, based on the structure, rendered gyrase inactive. CONCLUSIONS: Redx03863 and Redx04739 inhibit gyrase by preventing the binding of ATP. The fact that the Redx03863-binding pocket is distinct from that of novobiocin, coupled with the lack of activity of resistant mutants, suggests that such compounds could have potential to be further exploited as antibiotics.
Asunto(s)
Adenosina Trifosfatasas , Girasa de ADN , Mycobacterium , Adenosina Trifosfatasas/efectos de los fármacos , Mycobacteriaceae , Novobiocina/farmacología , Inhibidores de Topoisomerasa II/farmacologíaRESUMEN
Third-generation cephalosporin (3GC)-resistant Enterobacteriaceae are classified as critical priority pathogens, with extended-spectrum ß-lactamases (ESBLs) as principal resistance determinants. Enmetazobactam (formerly AAI101) is a novel ESBL inhibitor developed in combination with cefepime for empirical treatment of serious Gram-negative infections in settings where ESBLs are prevalent. Cefepime-enmetazobactam has been investigated in a phase 3 trial in patients with complicated urinary tract infections or acute pyelonephritis. This study examined pharmacokinetic-pharmacodynamic (PK-PD) relationships of enmetazobactam, in combination with cefepime, for ESBL-producing isolates of Klebsiella pneumoniae in 26-h murine neutropenic thigh infection models. Enmetazobactam dose fractionation identified the time above a free threshold concentration (fT > CT ) as the PK-PD index predictive of efficacy. Nine ESBL-producing isolates of K. pneumoniae, resistant to cefepime and piperacillin-tazobactam, were included in enmetazobactam dose-ranging studies. The isolates encoded CTX-M-type, SHV-12, DHA-1, and OXA-48 ß-lactamases and covered a cefepime-enmetazobactam MIC range from 0.06 to 2 µg/ml. Enmetazobactam restored the efficacy of cefepime against all isolates tested. Sigmoid curve fitting across the combined set of isolates identified enmetazobactam PK-PD targets for stasis and for a 1-log10 bioburden reduction of 8% and 44% fT > 2 µg/ml, respectively, with a concomitant cefepime PK-PD target of 40 to 60% fT > cefepime-enmetazobactam MIC. These findings support clinical dose selection and breakpoint setting for cefepime-enmetazobactam.
Asunto(s)
Cefalosporinas , Muslo , Animales , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Compuestos de Azabiciclo , Cefepima , Humanos , Klebsiella pneumoniae , Ratones , Pruebas de Sensibilidad Microbiana , Triazoles , beta-Lactamasas/genéticaRESUMEN
Iclaprim is a novel diaminopyrimidine, which inhibits bacterial dihydrofolate reductase, and it is active against Gram-positive pathogens including emerging drug-resistant pathogens. In vitro activity of iclaprim and comparators against 1365 Gram-positive clinical isolates from patients with skin and skin structure infections (SSSI) from the United States, Asia Pacific, Latin America, Europe, Africa or Middle East collected between 2013 and 2017 were tested. Susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI criteria. MIC90 for all S.aureus, methicillin-susceptible S. aureus, methicillin-resistant S. aureus, Streptococcus pyogenes, S. agalactiae, S. anginosus, S. constellatus, S. dysgalactiae and S. intermedius were 0.12, 0.12, 0.5, 0.03, 0.5, ≤0.004, ≤0.004, 0.12, and 0.008⯵g/ml, respectively. The MIC for iclaprim was 8 to 32-fold lower than trimethoprim, the only FDA approved dihydrofolate reductase inhibitor, against all Gram-positive isolates including resistant phenotypes. Iclaprim demonstrated lower MICs than trimethoprim against a collection (2013-2017) of Gram-positive clinical isolates from patients with SSSI from the United States, Asia Pacific, Latin America, and Europe.
Asunto(s)
Antibacterianos/farmacología , Bacterias Grampositivas/efectos de los fármacos , Vigilancia de la Población , Pirimidinas/farmacología , Enfermedades Cutáneas Infecciosas/microbiología , Piel/microbiología , África/epidemiología , Asia/epidemiología , Europa (Continente)/epidemiología , Antagonistas del Ácido Fólico , Salud Global/estadística & datos numéricos , Bacterias Grampositivas/enzimología , Bacterias Grampositivas/patogenicidad , Infecciones por Bacterias Grampositivas/epidemiología , Infecciones por Bacterias Grampositivas/microbiología , Humanos , América Latina/epidemiología , Pruebas de Sensibilidad Microbiana , Medio Oriente/epidemiología , Enfermedades Cutáneas Infecciosas/epidemiología , Tetrahidrofolato Deshidrogenasa/metabolismo , Estados Unidos/epidemiologíaRESUMEN
The incidence and patient outcomes of Staphylococcus aureus isolates by iclaprim MIC was determined among patients from two phase 3 studies for the treatment of acute bacterial skin and skin structure infections (ABSSSI), REVIVE-1 and -2. Iclaprim MIC90 values were 0.12 µg ml-1 for S. aureus (0.12 µg ml-1 against methicillin-sensitive and 0.25 µg ml-1 against methicillin-resistant S. aureus). The incidence of culture confirmed S. aureus isolates among patients with ABSSSI with an iclaprim MIC > 8 µg ml-1 was 2.0 â% (16/790). The clinical outcomes varied by MICs for early clinical response (63-100 â%), end of therapy response (81-100 â%) and the test of cure response (75-100 â%). For microbiological outcomes of these infections, the end of therapy response was 80-100 â% and the test of cure response was 88-100 â%.
Asunto(s)
Antibacterianos/farmacología , Pirimidinas/farmacología , Infecciones Cutáneas Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/efectos de los fármacos , Enfermedad Aguda , Método Doble Ciego , Humanos , Incidencia , Meticilina/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Piel/microbiología , Infecciones Cutáneas Estafilocócicas/epidemiología , Infecciones Cutáneas Estafilocócicas/microbiología , Vancomicina/farmacologíaRESUMEN
According to the World Health Organization (WHO), approximately 1.7 million deaths per year are caused by tuberculosis infections. Furthermore, it has been predicted that, by 2050, antibacterial resistance will be the cause of approximately 10 million deaths annually if the issue is not tackled. As a result, novel approaches to treating broad-spectrum bacterial infections are of vital importance. During the course of our wider efforts to discover unique methods of targeting multidrug-resistant (MDR) pathogens, we identified a novel series of amide-linked pyrimido[4,5-b]indol-8-amine inhibitors of bacterial type II topoisomerases. Compounds from the series were highly potent against gram-positive bacteria and mycobacteria, with excellent potency being retained against a panel of relevant Mycobacterium tuberculosis drug-resistant clinical isolates.
Asunto(s)
Antibacterianos/farmacología , Girasa de ADN/metabolismo , Diseño de Fármacos , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Inhibidores de Topoisomerasa II/farmacología , Antibacterianos/síntesis química , Antibacterianos/química , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Bacterias Grampositivas/metabolismo , Células Hep G2 , Humanos , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Estructura Molecular , Relación Estructura-Actividad , Inhibidores de Topoisomerasa II/síntesis química , Inhibidores de Topoisomerasa II/químicaRESUMEN
The novel bacterial topoisomerase inhibitor class is an investigational type of antibacterial inhibitor of DNA gyrase and topoisomerase IV that does not have cross-resistance with the quinolones. Here, we report the evaluation of the in vitro properties of a new series of this type of small molecule. Exemplar compounds selectively and potently inhibited the catalytic activities of Escherichia coli DNA gyrase and topoisomerase IV but did not block the DNA breakage-reunion step. Compounds showed broad-spectrum inhibitory activity against a wide range of Gram-positive and Gram-negative pathogens, including biodefence microorganisms and Mycobacterium tuberculosis No cross-resistance with fluoroquinolone-resistant Staphylococcus aureus and E. coli isolates was observed. Measured MIC90 values were 4 and 8 µg/ml against a panel of contemporary multidrug-resistant isolates of Acinetobacter baumannii and E. coli, respectively. In addition, representative compounds exhibited greater antibacterial potency than the quinolones against obligate anaerobic species. Spontaneous mutation rates were low, with frequencies of resistance typically <10-8 against E. coli and A. baumannii at concentrations equivalent to 4-fold the MIC. Compound-resistant E. coli mutants that were isolated following serial passage were characterized by whole-genome sequencing and carried a single Arg38Leu amino acid substitution in the GyrA subunit of DNA gyrase. Preliminary in vitro safety data indicate that the series shows a promising therapeutic index and potential for low human ether-a-go-go-related gene (hERG) inhibition (50% inhibitory concentration [IC50], >100 µM). In summary, the compounds' distinct mechanism of action relative to the fluoroquinolones, whole-cell potency, low potential for resistance development, and favorable in vitro safety profile warrant their continued investigation as potential broad-spectrum antibacterial agents.
Asunto(s)
Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/farmacología , Topoisomerasa de ADN IV/antagonistas & inhibidores , Escherichia coli/efectos de los fármacos , Mycobacterium tuberculosis/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Inhibidores de Topoisomerasa II/farmacología , Ciprofloxacina/farmacología , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Humanos , Pruebas de Sensibilidad MicrobianaRESUMEN
There is an urgent and unmet medical need for new antibacterial drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. During the course of our wider efforts to discover and exploit novel mechanism of action antibacterials, we have identified a novel series of isothiazolone based inhibitors of bacterial type II topoisomerase. Compounds from the class displayed excellent activity against both Gram-positive and Gram-negative bacteria with encouraging activity against a panel of MDR clinical Escherichia coli isolates when compared to ciprofloxacin. Representative compounds also displayed a promising in vitro safety profile.
Asunto(s)
Antibacterianos/química , ADN-Topoisomerasas de Tipo II/metabolismo , Tiazoles/química , Tiazolidinas/química , Inhibidores de Topoisomerasa II/química , Antibacterianos/síntesis química , Antibacterianos/farmacología , Supervivencia Celular/efectos de los fármacos , ADN-Topoisomerasas de Tipo II/química , Evaluación Preclínica de Medicamentos , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Células Hep G2 , Humanos , Pruebas de Sensibilidad Microbiana , Mutación , Relación Estructura-Actividad , Tiazoles/síntesis química , Tiazoles/farmacología , Tiazolidinas/síntesis química , Tiazolidinas/farmacología , Inhibidores de Topoisomerasa II/síntesis química , Inhibidores de Topoisomerasa II/farmacologíaRESUMEN
There is an urgent need for new antibiotics to treat multidrug-resistant Neisseria gonorrhoeae In this report, the microbiology, in vivo pharmacokinetics, and efficacy of REDX05931, a representative novel tricyclic topoisomerase inhibitor, were evaluated. REDX05931 demonstrated high oral bioavailability in mice and reduced N. gonorrhoeae infection after a single dose in a mouse model of gonorrhea. These data support the potential of this series of small molecules as a new treatment for drug-resistant gonorrheal infections.
Asunto(s)
Antibacterianos/farmacología , Gonorrea/tratamiento farmacológico , Neisseria gonorrhoeae/efectos de los fármacos , Inhibidores de Topoisomerasa/farmacología , Animales , Modelos Animales de Enfermedad , Gonorrea/microbiología , Ratones , Pruebas de Sensibilidad MicrobianaRESUMEN
OBJECTIVES: To evaluate the in vitro biological properties of a novel class of isothiazolone inhibitors of the bacterial type II topoisomerases. METHODS: Inhibition of DNA gyrase and topoisomerase IV activity was assessed using DNA supercoiling and decatenation assays. MIC and MBC were determined according to CLSI guidelines. Antibacterial combinations were assessed using a two-dimensional chequerboard MIC method. Spontaneous frequency of resistance was measured at various multiples of the MIC. Resistant mutants were generated by serial passage at subinhibitory concentrations of antibacterials and genetic mutations were determined through whole genome sequencing. Mammalian cytotoxicity was evaluated using the HepG2 cell line. RESULTS: Representative isothiazolone compound REDX04957 and its enantiomers (REDX05967 and REDX05990) showed broad-spectrum bactericidal activity against the ESKAPE organisms, with the exception of Enterococcus spp., as well as against a variety of other human bacterial pathogens. Compounds retained activity against quinolone-resistant strains harbouring GyrA S83L and D87G mutations (MIC ≤4 mg/L). Compounds inhibited the supercoiling activity of wild-type DNA gyrase and the decatenation function of topoisomerase IV. Frequency of resistance of REDX04957 at 4× MIC was <9.1â×â10(-9). Against a panel of recent MDR isolates, REDX05967 demonstrated activity against Acinetobacter baumannii with MIC50 and MIC90 of 16 and 64 mg/L, respectively. Compounds showed a lack of cytotoxicity against HepG2 cells at 128 mg/L. CONCLUSIONS: Isothiazolone compounds show potent activity against Gram-positive and -negative pathogens with a dual targeting mechanism-of-action and a low potential for resistance development, meriting their continued investigation as broad-spectrum antibacterial agents.
Asunto(s)
Antibacterianos/farmacología , ADN-Topoisomerasas de Tipo II/metabolismo , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Tiazoles/farmacología , Inhibidores de Topoisomerasa II/farmacología , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/enzimología , Acinetobacter baumannii/genética , Técnicas de Tipificación Bacteriana , Girasa de ADN/metabolismo , Topoisomerasa de ADN IV/antagonistas & inhibidores , ADN Bacteriano/metabolismo , Enterococcus/efectos de los fármacos , Enterococcus/enzimología , Bacterias Gramnegativas/enzimología , Bacterias Grampositivas/enzimología , Células Hep G2 , Humanos , Pruebas de Sensibilidad Microbiana , Mutación , Tiazoles/química , Tiazoles/aislamiento & purificación , Tiazoles/metabolismo , Inhibidores de Topoisomerasa II/química , Inhibidores de Topoisomerasa II/aislamiento & purificaciónRESUMEN
OBJECTIVES: The objective of this study was to characterize the in vitro and in vivo biological properties of a novel series of small-molecule bacterial type IIA topoisomerase inhibitors. METHODS: Bacterial susceptibility testing was performed by broth microdilution. Resistance frequencies were determined by plating bacteria onto agar containing test compound and enumerating mutants. Bacteria were passaged using subinhibitory concentrations of antibacterials to generate resistance. Target enzyme inhibition was determined by exposure to antibacterials and DNA; topoisomers were visualized by gel electrophoresis. Oral and intravenous pharmacokinetic profiles were determined in mice. In vivo efficacy was determined using a mouse model of septicaemia and thigh infection with MSSA and MRSA, respectively. RESULTS: Representative compounds REDX04139, REDX05604 and REDX05931 demonstrated in vitro potency against a range of Gram-positive and fastidious Gram-negative pathogens. Clinical isolate testing revealed REDX04139 and REDX05931 had MIC90 values of 0.25 and 0.5 mg/L, respectively, for MRSA and MIC90 values of 2 mg/L for streptococci. REDX04139 was bactericidal in vitro against Staphylococcus aureus at 8× MIC over 6 h. Pharmacokinetic profiling of REDX04139 and REDX05604 in mice revealed low clearance and excellent bioavailability (≥71%). REDX04139 provided 100% survival against S. aureus in a mouse septicaemia model, while REDX05604 reduced bacterial load by up to 3.7 log units in the MRSA mouse thigh infection model. CONCLUSIONS: Redx Pharma has discovered a novel series of topoisomerase inhibitors that are being further developed for drug-resistant bacteria.
Asunto(s)
Antibacterianos/farmacología , Girasa de ADN/metabolismo , Topoisomerasa de ADN IV/antagonistas & inhibidores , Hidrocarburos Cíclicos/farmacología , Staphylococcus/efectos de los fármacos , Animales , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacocinética , Disponibilidad Biológica , Supervivencia Celular/efectos de los fármacos , Modelos Animales de Enfermedad , Células Hep G2 , Humanos , Hidrocarburos Cíclicos/aislamiento & purificación , Hidrocarburos Cíclicos/farmacocinética , Masculino , Ratones , Pruebas de Sensibilidad Microbiana , Sepsis/tratamiento farmacológico , Sepsis/microbiología , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/microbiología , Streptococcus/efectos de los fármacos , Análisis de SupervivenciaRESUMEN
BACKGROUND: There remains a critical need for more effective, safe, long-term treatments for cystic fibrosis (CF). Any successful therapeutic strategy designed to combat the respiratory pathology of this condition must address the altered lung physiology and recurrent, complex, polymicrobial infections and biofilms that affect the CF pulmonary tract. Cysteamine is a potential solution to these unmet medical needs and is described here for the first time as (Lynovex®) a single therapy with the potential to deliver mucoactive, antibiofilm and antibacterial properties; both in oral and inhaled delivery modes. Cysteamine is already established in clinical practice for an unrelated orphan condition, cystinosis, and is therefore being repurposed (in oral form) for cystic fibrosis from a platform of over twenty years of safety data and clinical experience. METHODS: The antibacterial and antibiofilm attributes of cysteamine were determined against type strain and clinical isolates of CF relevant pathogens using CLSI standard and adapted microbiological methods and a BioFlux microfluidic system. Assays were performed in standard nutrient media conditions, minimal media, to mimic the low metabolic activity of microbes/persister cells in the CF respiratory tract and in artificial sputum medium. In vivo antibacterial activity was determined in acute murine lung infection/cysteamine nebulisation models. The mucolytic potential of cysteamine was assessed against DNA and mucin in vitro by semi-quantitative macro-rheology. In all cases, the 'gold standard' therapeutic agents were employed as control/comparator compounds against which the efficacy of cysteamine was compared. RESULTS: Cysteamine demonstrated at least comparable mucolytic activity to currently available mucoactive agents. Cysteamine was rapidly bactericidal against both metabolically active and persister cells of Pseudomonas aeruginosa and also emerging CF pathogens; its activity was not sensitive to high ionic concentrations characteristic of the CF lung. Cysteamine prevented the formation of, and disrupted established P. aeruginosa biofilms. Cysteamine was synergistic with conventional CF antibiotics; reversing antibiotic resistance/insensitivity in CF bacterial pathogens. CONCLUSIONS: The novel mucolytic-antimicrobial activity of cysteamine (Lynovex®) provides potential for a much needed new therapeutic strategy in cystic fibrosis. The data we present here provides a platform for cysteamine's continued investigation as a novel treatment for this poorly served orphan disease.
Asunto(s)
Antiinfecciosos/farmacología , Biopelículas/efectos de los fármacos , Cisteamina/farmacología , Fibrosis Quística/microbiología , Expectorantes/farmacología , Mucinas/metabolismo , Animales , Antiinfecciosos/uso terapéutico , Biopelículas/crecimiento & desarrollo , Cisteamina/uso terapéutico , Fibrosis Quística/tratamiento farmacológico , Fibrosis Quística/metabolismo , Expectorantes/uso terapéutico , Humanos , Masculino , Ratones , Ratones Endogámicos ICR , Pruebas de Sensibilidad Microbiana/métodos , Porcinos , Resultado del TratamientoRESUMEN
Histone deacetylase inhibitors (HDACi) have shown promising antitumor effects on numerous cancer cells including malignant pleural mesothelioma (MPM) and lung adenocarcinoma (ADCA) cells. However, clinical trials using these compounds alone have shown limited efficacy against solid tumors. Therefore, new molecules are being developed and combinations with classical chemotherapeutic drugs are being tested. Here, we have evaluated on three MPM and three lung ADCA cell lines the antitumor potential of four new HDACi compounds, either alone or in combination with cisplatin. These effects were compared with those of vorinostat, an HDACi approved for cancer treatments. First, we characterized the HDAC mRNA expression profiles of tumor cells and showed an increase of the classI/classII HDAC ratio. We then treated cancer cells with these new HDACi and observed a cell-death induction and an increase of HDACi target genes and proteins expression. This was particularly evident for NODH compound (pan-HDACi) which had similar effects at nanomolar concentrations as micromolar concentrations of vorinostat. Interestingly, we observed that the HDACi/cisplatin combination strongly increased cell-death and limited resistance-phenotype emergence as compared with results obtained when the drugs were used alone. These results could be exploited to develop MPM and lung ADCA treatments combining chemotherapeutic approaches.
Asunto(s)
Cisplatino/farmacología , Inhibidores de Histona Desacetilasas/metabolismo , Neoplasias Torácicas/metabolismo , Apoptosis , Línea Celular Tumoral , HumanosRESUMEN
A Gram-positive, spore-forming, non-motile, strictly anaerobic rod-shaped bacterium was isolated from the caecal content of a TNF(deltaARE) mouse. The isolate, referred to as strain SRB-521-5-I(T), was originally cultured on a reduced agar medium containing yeast extract, rumen fluid and lactic acid as main energy and carbon sources. Phylogenetic analysis of partial 16S rRNA genes revealed that the species most closely related to strain SRB-521-5-I(T) were Flavonifractor plautii and Pseudoflavonifractor capillosus (<95â% sequence similarity; 1436 bp). In contrast to F. plautii and P. capillosus, strain SRB-521-5-I(T) contained a substantial amount of C18â:â0 dimethylacetal. Additional major fatty acids were C14â:â0 methyl ester, C16â:â0 dimethylacetal and C18â:â0 aldehyde. Strain SRB-521-5-I(T) differed in its enzyme profile from F. plautii and P. capillosus by being positive for dextrin, maltotriose, turanose, dl-lactic acid and d-lactic acid methyl ester but negative for d-fructose. In reduced Wilkins-Chalgren-Anaerobe broth, strain SRB-521-5-I(T) produced approximately 8 mM butyrate and 4 mM acetate. In contrast to F. plautii, the strain did not metabolize flavonoids. It showed intermediate resistance towards the antibiotics ciprofloxacin, colistin and tetracycline. Based on genotypic and phenotypic characteristics, we propose the name Intestinimonas butyriciproducens gen. nov., sp. nov. to accommodate strain SRB-521-5-I(T) (â=âDSM 26588(T)â=âCCUG 63529(T)) as the type strain.
Asunto(s)
Butiratos/metabolismo , Bacilos Grampositivos Formadores de Endosporas/clasificación , Intestinos/microbiología , Filogenia , Animales , Bacterias Anaerobias/clasificación , Bacterias Anaerobias/genética , Bacterias Anaerobias/aislamiento & purificación , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Femenino , Bacilos Grampositivos Formadores de Endosporas/genética , Bacilos Grampositivos Formadores de Endosporas/aislamiento & purificación , Ratones , Datos de Secuencia Molecular , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
An unknown impurity detected in small amounts during the heat treatment of artesunate-amodiaquine bilayer tablets was purified by semipreparative HPLC and identified by MS and NMR as the tetrahydrofuranyl acetate-rearranged derivative of anhydrodihydroartemisinin. When anhydrodihydroartemisinin was treated with a Fe(II) salt in acetonitrile-water solution, the same product was generated, together with an isomeric 2-deoxy-4α-hydroxy-anhydrodihydroartemisinin derivative, as expected from the usual homolytic radical opening of the endoperoxide bond previously described for other artemisinin derivatives.
Asunto(s)
Amodiaquina/química , Antimaláricos/química , Artemisininas/química , Cromatografía Líquida de Alta Presión/métodos , Amodiaquina/análisis , Antimaláricos/análisis , Artemisininas/análisis , Artemisininas/aislamiento & purificación , Combinación de Medicamentos , Contaminación de Medicamentos , Estabilidad de Medicamentos , Almacenaje de Medicamentos , Espectroscopía de Resonancia Magnética/métodos , Espectrometría de Masas/métodos , ComprimidosRESUMEN
A single strain, NR06(T), was isolated from the intestine of a TNF(deltaARE) mouse. Based on phylogenetic analysis of partial 16S rRNA gene sequences, strain NR06(T) belongs in the family Coriobacteriaceae within the Actinobacteria. The most closely related species with validly published names are members of the genera Adlercreutzia, Asaccharobacter and Enterorhabdus (<96 % sequence similarity). Strain NR06(T) was characterized by a high prevalence of monomethylmenaquinone-6 (MMK-6; 76 %) and the presence of meso-diaminopimelic acid in the cell wall. One of the major cellular fatty acids of strain NR06(T) was C15 : 0 ISO. Glucose was detected as a whole cell sugar. Strain NR06(T) was resistant to the antibiotic colistin and was positive for arginine and leucine arylamidase activity. Based on these characteristics, strain NR06(T) differed from related described bacteria. Therefore, the name Parvibacter caecicola gen. nov., sp. nov. is proposed to accommodate the novel bacterium. The type strain of the type species is NR06(T) ( = DSM 22242(T) = CCUG 57646(T)).
Asunto(s)
Actinobacteria/clasificación , Ciego/microbiología , Filogenia , Actinobacteria/genética , Actinobacteria/aislamiento & purificación , Animales , Técnicas de Tipificación Bacteriana , ADN Bacteriano/genética , Ácido Diaminopimélico/análisis , Ácidos Grasos/análisis , Masculino , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Vitamina K 2/análogos & derivados , Vitamina K 2/análisisRESUMEN
We report the characterization of one novel bacterium, strain ERD01G(T), isolated from the cecum of a TNF(deltaARE) mouse. The strain was found to belong to the genus Streptococcus based on phylogenetic analysis of partial 16S rRNA gene sequences. The bacterial species with standing name in nomenclature that was most closely related to our isolate was Streptococcus alactolyticus (97 %). The two bacteria were characterized by a DNA-DNA hybridization similarity value of 35 %, demonstrating that they belong to different species. The new isolate was negative for acetoin production, esculin hydrolysis, urease, α-galactosidase and ß-glucosidase, was able to produce acid from starch and trehalose, grew as beta-hemolytic coccobacilli on blood agar, did not grow at >40 °C, did not survive heat treatment at 60 °C for 20 min and showed negative agglutination in Lancefield tests. On the basis of these characteristics, strain ERD01G(T) differed from the most closely related species S. alactolyticus, Streptococcus gordonii, Streptococcus intermedius and Streptococcus sanguinis. Thus, based on genotypic and phenotypic evidence, we propose that the isolate belongs to a novel bacterial taxon within the genus Streptococcus, for which the name Streptococcus danieliae is proposed. The type strain is ERD01G(T) (= DSM 22233(T) = CCUG 57647(T)).
Asunto(s)
Ciego/microbiología , Filogenia , Streptococcus/clasificación , Animales , Secuencia de Bases , ADN Bacteriano/genética , Genotipo , Masculino , Ratones , Ratones Endogámicos C57BL , Microscopía de Contraste de Fase , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , ARN Ribosómico 16S/genética , Especificidad de la Especie , Streptococcus/citología , Streptococcus/genética , Streptococcus/aislamiento & purificación , Ureasa/genética , alfa-Galactosidasa/genéticaRESUMEN
Caecal samples from wild-type and TNF(deltaARE) mice were cultured on selective media containing bile salts, amino acids or casein macro-peptides. Twenty-two strains were isolated and identified by 16S rRNA gene sequencing. Twenty-one strains showed >98% similarity to known bacteria (Blautia spp., Clostridium innocuum, Enterococcus spp., Escherichia coli, Lactobacillus murinus, Parabacteroides goldsteinii and Shigella dysenteriae). One additional isolate, strain A-C2-0, was a new bacterium. The closest relatives were Bacteroides massiliensis, Bacteroides dorei and Bacteroides vulgatus (< or = 94% similarity). Strain A-C2-0 is a Gram-negative rod that does not form spores and has a G + C content of DNA of 41.5%. Its major cellular fatty acid is C(15:0 ANTEISO), and its major respiratory quinone is MK-9. Cells are aerotolerant but grow only under strict anoxic conditions. They are resistant to cefotaxime and tobramycin. When compared with related Bacteroides spp., the new bacterium was positive for alpha-arabinosidase, negative for glutamyl glutamic acid arylamidase and did not metabolise galactose, glucose, fructose, mannose, raffinose and sucrose. Strain A-C2-0 therefore merits recognition as a member of a novel species within the genus Bacteroides, for which the name Bacteroides sartorii is proposed. The type strain is A-C2-0(T) (= DSM 21941(T) = CCUG 57211(T)).
Asunto(s)
Bacteroides/clasificación , Bacteroides/aislamiento & purificación , Ciego/microbiología , Animales , Bacteroides/genética , Bacteroides/fisiología , Composición de Base , Medios de Cultivo , ADN Bacteriano/química , ADN Bacteriano/genética , Ácidos Grasos/análisis , Genes Bacterianos , Genes de ARNr , Genotipo , Masculino , Ratones , Ratones Endogámicos C57BL , Fenotipo , Filogenia , Análisis de Secuencia de ADNRESUMEN
The C3H/HeJBir mouse model of intestinal inflammation was used for isolation of a Gram-positive, rod-shaped, non-spore-forming bacterium (B7(T)) from caecal suspensions. On the basis of partial 16S rRNA gene sequence analysis, strain B7(T) was a member of the class Actinobacteria, family Coriobacteriaceae, and was related closely to Enterorhabdus mucosicola Mt1B8(T) (97.6 %). The major fatty acid of strain B7(T) was C(16 : 0) (19.1 %) and the respiratory quinones were mono- and dimethylated. Cells were aerotolerant, but grew only under anoxic conditions. Strain B7(T) did not convert the isoflavone daidzein and was resistant to cefotaxime. The results of DNA-DNA hybridization experiments and additional physiological and biochemical tests allowed the genotypic and phenotypic differentiation of strain B7(T) from the type strain of E. mucosicola. Therefore, strain B7(T) represents a novel species, for which the name Enterorhabdus caecimuris sp. nov. is proposed. The type strain is B7(T) (=DSM 21839(T) =CCUG 56815(T)).
Asunto(s)
Actinobacteria/clasificación , Colitis/microbiología , Actinobacteria/genética , Actinobacteria/aislamiento & purificación , Actinobacteria/fisiología , Animales , Secuencia de Bases , Cromatografía Líquida de Alta Presión , Lípidos/análisis , Ratones , Ratones Endogámicos C3H , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , ARN Ribosómico 16S/genética , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
The diversity of bacteria associated with inflamed mucosa was investigated by culturing ileal samples from TNF(deltaARE) mice on a selective medium containing mucin. Among eight isolates, two strains (Mt1B3 and Mt1B8(T)) belonged to bacterial groups not yet cultured from the mouse intestine. Whereas strain Mt1B3 was identified as a member of the family Planococcaceae and is closely related to Sporosarcina species and Filibacter limicola DSM 13886(T), strain Mt1B8(T) was a novel bacterium. Based on phylogenetic analysis, strain Mt1B8(T) is a member of the family Coriobacteriaceae. The closest relatives with validly published names were Asaccharobacter celatus, Adlercreutzia equolifaciens (<96 % similarity) and Eggerthella species (<92 %). With respect to Asaccharobacter celatus and Eggerthella, the phylogenetic position of strain Mt1B8(T) was confirmed at the chemotaxonomic level by Fourier-transform infrared spectroscopic analysis. The major fatty acid of strain Mt1B8(T) is C(16 : 0) (23.9 %). Menaquinones were monomethylated. DNA-DNA relatedness between strain Mt1B8(T) and Asaccharobacter celatus DSM 18785(T) was 28 %. Strain Mt1B8(T) is a Gram-positive-staining rod that does not form spores and has a high DNA G+C content (64.2 mol%). Cells are aerotolerant but grow only under strictly anoxic conditions. They are sensitive to cefotaxime, clarithromycin, erythromycin, metronidazole, tetracycline, tobramycin and vancomycin. API and VITEK analysis showed the ability of strain Mt1B8(T) to convert a variety of amino acid derivatives. According to these findings, it is proposed to create a novel genus and species, Enterorhabdus mucosicola gen. nov., sp. nov., to accommodate strain Mt1B8(T). The type strain of Enterorhabdus mucosicola is Mt1B8(T) (=DSM 19490(T) =CCUG 54980(T)).