RESUMEN
Frequencies of mutation to resistance with trovafloxacin and four other quinolones were determined with quinolone-susceptible Staphylococcus aureus RN4220 by a direct plating method. First-step mutants were selected less frequently with trovafloxacin (1.1 x 10(-10) at 2 to 4x the MIC) than with levofloxacin or ciprofloxacin (3.0 x 10(-7) to 3.0 x 10(-8) at 2 to 4x the MIC). Mutants with a change in GrlA (Ser80-->Phe or Tyr) were most commonly selected with trovafloxacin, ciprofloxacin, levofloxacin, or pefloxacin. First-step mutants were difficult to select with sparfloxacin; however, second-step mutants with mutations in gyrA were easily selected when a preexisting mutation in grlA was present. Against 29 S. aureus clinical isolates with known mutations in gyrA and/or grlA, trovafloxacin was the most active quinolone tested (MIC at which 50% of isolates are inhibited [MIC(50)] and MIC(90), 1 and 4 microg/ml, respectively); in comparison, MIC(50)s and MIC(90)s were 32 and 128, 16 and 32, 8 and 32, and 128 and 256 microg/ml for ciprofloxacin, sparfloxacin, levofloxacin, and pefloxacin, respectively. Strains with a mutation in grlA only were generally susceptible to all of the quinolones tested. For mutants with changes in both grlA and gyrA MICs were higher and were generally above the susceptibility breakpoint for ciprofloxacin, sparfloxacin, levofloxacin, and pefloxacin. Addition of reserpine (20 microg/ml) lowered the MICs only of ciprofloxacin fourfold or more for 18 of 29 clinical strains. Topoisomerase IV and DNA gyrase genes were cloned from S. aureus RN4220 and from two mutants with changes in GrlA (Ser80-->Phe and Glu84-->Lys). The enzymes were overexpressed in Escherichia coli GI724, purified, and used in DNA catalytic and cleavage assays that measured the relative potency of each quinolone. Trovafloxacin was at least five times more potent than ciprofloxacin, sparfloxacin, levofloxacin, or pefloxacin in stimulating topoisomerase IV-mediated DNA cleavage. While all of the quinolones were less potent in cleavage assays with the altered topoisomerase IV, trovafloxacin retained its greater potency relative to those of the other quinolones tested. The greater intrinsic potency of trovafloxacin against the lethal topoisomerase IV target in S. aureus contributes to its improved potency against clinical strains of S. aureus that are resistant to other quinolones.
Asunto(s)
Antiinfecciosos/farmacología , ADN-Topoisomerasas de Tipo II/genética , Inhibidores Enzimáticos/farmacología , Fluoroquinolonas , Naftiridinas/farmacología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/enzimología , Inhibidores de Topoisomerasa II , Inhibidores de Captación Adrenérgica/farmacología , Antituberculosos/farmacología , Ciprofloxacina/farmacología , Girasa de ADN , Topoisomerasa de ADN IV , ADN-Topoisomerasas de Tipo II/aislamiento & purificación , ADN-Topoisomerasas de Tipo II/metabolismo , ADN Bacteriano/biosíntesis , ADN Bacteriano/metabolismo , ADN Superhelicoidal/metabolismo , Interacciones Farmacológicas , Farmacorresistencia Microbiana , Levofloxacino , Pruebas de Sensibilidad Microbiana , Mutación , Ofloxacino/farmacología , Reserpina/farmacología , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
The in vitro activity of CP-99,219 was compared with that of ciprofloxacin and sparfloxacin against 814 clinical bacterial isolates using a microdilution method with brain-heart infusion broth. CP-99,219 was the most potent agent tested against methicillin-resistant, ciprofloxacin-susceptible staphylocci (minimum inhibitory concentration [MIC]90 < or = 0.25 microgram/ml). CP-99,219 was 32-fold and fourfold more potent than ciprofloxacin and sparfloxacin, respectively, against Streptococcus pneumoniae, including strains resistant to penicillin G and erythromycin (MIC90 < or = 0.25 microgram/ml). CP-99,219 was also the most potent agent tested against S. pyogenes and Enterococcus faecalis (MIC90 < or = 0.5 microgram/ml). The activity of CP-99,219 against Enterobacteriaceae was comparable to that of sparfloxacin, with 90% of Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella pneumoniae, Citrobacter freundii, C. diversus, Helicobacter pylori, and K. oxytoca being inhibited by < or = 0.5 microgram/ml. Serratia marcescens, Morganella morganii, and Pseudomonas aeruginosa were less susceptible, with MIC90 values to CP-99,219 of 4, 2, and 2 micrograms/ml, respectively. The MIC90 for Bacteroides fragilis was 0.39 microgram/ml for CP-99,219 compared with 12.5 micrograms/ml for ciprofloxacin. CP-99,219 was highly bactericidal at 1 x to 4 x MIC against both Gram-positive and Gram-negative organisms; its activity was similar in nutrient, trypticase soy, and cation-supplemented Mueller-Hinton broths. The spectrum and potency observed with CP-99,219 warrant further testing with this novel quinolone.
Asunto(s)
Antiinfecciosos/farmacología , Ciprofloxacina/farmacología , Fluoroquinolonas , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Naftiridinas/farmacología , Quinolonas/farmacología , ADN-Topoisomerasas de Tipo II , ADN Bacteriano/efectos de los fármacos , Pruebas de Sensibilidad MicrobianaRESUMEN
Bisulfite or sulfite was found to be inhibitory to Helicobacter pylori growth. A modified version of Brucella broth (BB), bisulfite-less BB (BLBB), supported rapid, robust, and consistent growth of H. pylori. We suggest that BLBB simply be called "Pylori broth" for distinction from Brucella broth.
Asunto(s)
Medios de Cultivo , Helicobacter pylori/efectos de los fármacos , Helicobacter pylori/crecimiento & desarrollo , Sulfitos/farmacología , Técnicas Bacteriológicas , Medios de Cultivo/química , Estudios de Evaluación como Asunto , Helicobacter pylori/aislamiento & purificación , Humanos , Oxidación-ReducciónRESUMEN
Several substituted analogs of 7-(cis-3,5-dimethylpiperazinyl)-6,8-difluoro-5-amino-1-cyclopropyl quinolone were prepared and tested in a DNA cleavage assay with calf thymus topoisomerase II. Positioning of the methyl groups on the C-7 piperazine ring influenced potency against the mammalian enzyme; the cis-3,5-dimethyl configuration did not stimulate cleavage at drug concentrations less than or equal to 2,000 microM, while the trans configuration was active at drug levels as low as 36 microM. Removal of the cis-methyl groups produced a compound that was only sixfold less potent than the antitumor agent etoposide in stimulating enzyme-mediated DNA cleavage. The cis- and trans-methyl substitutions on the piperazine that conferred potency against the mammalian type II enzyme had little effect on bacterial DNA gyrase cleavage activity, suggesting that an asymmetric barrier exists with the mammalian enzyme which influences productive quinolone interaction, favoring the less bulky trans-3,5-dimethylpiperazine substituent at C-7.
Asunto(s)
Antiinfecciosos/farmacología , Inhibidores de Topoisomerasa II , Animales , Cristalografía por Rayos X , ADN/metabolismo , Etopósido/farmacología , Fluoroquinolonas , Conformación Molecular , Relación Estructura-ActividadRESUMEN
A series of novel 6-fluoro-7-diazabicycloalkylquinolonecarboxylic acids substituted with various C8 (H, F, Cl, N) and N1 (ethyl, cyclopropyl, vinyl, 2-fluoroethyl, 4-fluorophenyl, 2,4-difluorophenyl) substituents, as well as, 9-fluoro-10-diazabicycloalkylpyridobenzoxazinecarboxylic acids, were prepared and evaluated for antibacterial activity against a range of important veterinary pathogenic bacteria. The diazabicycloalkyl side chains investigated at the 7-position (benzoxazine 10-position) include (1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]heptane (2), (1S,4S)-2,5-diazabicyclo[2.2.1]heptane (3), (1R,4R)-5-methyl-2,5-diazabicyclo[2.2.1]heptane (4), 8-methyl-3,8-diazabicyclo[3.2.1]octane (5), 9-methyl-3,9-diazabicyclo[4.2.1]nonane (6), 1,4-diazabicyclo[3.2.2]nonane (7), 1,4-diazabicyclo[3.3.1]nonane (8), and 9-methyl-3,9-diazabicyclo[3.3.1]nonane (9). Among these side chains, in vitro potency was not highly variable; other properties therefore proved more critical to the selection of possible development candidates. However, the relative potencies observed for several of these compounds in mouse, swine, and cattle infection models correlated well with those seen in vitro. A combination of the N1 cyclopropyl group and the C7 (1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]hept-2-yl appendage conferred the best overall antibacterial, physiochemical, and pharmacodynamic properties. Hence, danofloxacin (Advocin, 2c) (originally CP-76,136, 1-cyclopropyl-6-fluoro-7-[(1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1] hept-2-yl]-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid) was selected as a candidate for development as a therapeutic antibacterial agent for veterinary medicine.
Asunto(s)
Antiinfecciosos/síntesis química , Infecciones Bacterianas/veterinaria , Fluoroquinolonas , Quinolonas/síntesis química , Infecciones por Actinobacillus/tratamiento farmacológico , Infecciones por Actinobacillus/veterinaria , Actinobacillus pleuropneumoniae , Aerobiosis , Anaerobiosis , Animales , Antiinfecciosos/farmacología , Antiinfecciosos/uso terapéutico , Infecciones Bacterianas/tratamiento farmacológico , Bovinos , Enfermedades de los Bovinos/tratamiento farmacológico , Femenino , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Ratones , Estructura Molecular , Infecciones por Pasteurella/tratamiento farmacológico , Infecciones por Pasteurella/veterinaria , Quinolonas/farmacología , Quinolonas/uso terapéutico , Relación Estructura-Actividad , Porcinos , Enfermedades de los Porcinos/tratamiento farmacológicoRESUMEN
Azithromycin (CP-62,993), a new acid-stable 15-membered-ring macrolide, was well absorbed following oral administration in mice, rats, dogs, and cynomolgus monkeys. This compound exhibited a uniformly long elimination half-life and was distributed exceptionally well into all tissues. This extravascular penetration of azithromycin was demonstrated by tissue/plasma area-under-the-curve ratios ranging from 13.6 to 137 compared with ratios for erythromycin of 3.1 to 11.6. The significance of these pharmacokinetic advantages of azithromycin over erythromycin was shown through efficacy in a series of animal infection models. Azithromycin was orally effective in treating middle ear infections induced in gerbils by transbulla challenges with amoxicillin-resistant Haemophilus influenzae or susceptible Streptococcus pneumoniae; erythromycin failed and cefaclor was only marginally active against the H. influenzae challenge. Azithromycin was equivalent to cefaclor and erythromycin against Streptococcus pneumoniae. In mouse models, the new macrolide was 10-fold more potent than erythromycin and four other antibiotics against an anaerobic infection produced by Fusobacterium necrophorum. Similarly, azithromycin was effective against established tissue infections induced by Salmonella enteritidis (liver and spleen) and Staphylococcus aureus (thigh muscle); erythromycin failed against both infections. The oral and subcutaneous activities of azithromycin, erythromycin, and cefaclor were similar against acute systemic infections produced by Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus viridans, or S. aureus, whereas azithromycin was more potent than erythromycin and cefaclor against the intracellular pathogen Listeria monocytogenes. The pharmacokinetic advantage of azithromycin over erythromycin in half-life was clearly demonstrated in prophylactic treatment of an acute mouse model of S. aureus infection. These properties of azithromycin strongly support the further evaluation of this new macrolide for use in community-acquired infections of skin or soft tissue and respiratory diseases.
Asunto(s)
Antibacterianos/farmacocinética , Eritromicina/análogos & derivados , Animales , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Azitromicina , Infecciones Bacterianas/tratamiento farmacológico , Infecciones Bacterianas/microbiología , Modelos Animales de Enfermedad , Eritromicina/farmacocinética , Eritromicina/farmacología , Eritromicina/uso terapéutico , Femenino , Gerbillinae , Semivida , Haplorrinos , Masculino , Ratas , Especificidad de la Especie , Distribución TisularRESUMEN
6-(Heterocyclyl)methylene penam sulfones (1) are effective beta-lactamase inhibitors and potent ampicillin and cefazolin potentiators against both Gram-positive and Gram-negative beta-lactamase producing bacteria. Several of these analogs having a pi-deficient 2-heteroaryl substituent attached to the C6-methylene position showed better inhibitory activity than clavulanic acid, Ro 15-1903, 6 beta-bromopenicillanic acid, and sulbactam against a variety of beta-lactamases. The compounds were devoid of any antibacterial activity, but in combination with ampicillin or cefazolin, exhibited synergistic activity at least equal to clavulanic acid, Ro 15-1903, 6 beta-bromopenicillanic acid or sulbactam against beta-lactamase producing strains. Structure-activity relationships for a number of compounds are described. The structure-activity relationships can be rationalized by an enzyme inhibition mechanism which we have previously proposed on the basis of methanolysis of 6-(2-pyridyl)methylene penam sulfone (1a). Two synthetic routes to prepare compounds of structural type 1 via either a Wittig reaction or an aldol condensation are reported. beta-Lactamase inhibition and MIC data are presented.
Asunto(s)
Sulfonas/farmacología , Inhibidores de beta-Lactamasas , Ampicilina/farmacología , Cefazolina/farmacología , Fenómenos Químicos , Química , Sinergismo Farmacológico , Bacterias Gramnegativas/enzimología , Bacterias Grampositivas/enzimología , Espectroscopía de Resonancia Magnética , Espectrofotometría , Relación Estructura-ActividadRESUMEN
The irreversible beta-lactamase inhibitor sulbactam has been combined chemically via ester linkages with ampicillin to form sultamicillin . Upon oral absorption, sultamicillin is completely hydrolyzed to equimolar proportions of sulbactam and ampicillin, thereby acting as an efficient mutual prodrug. In rats, sultamicillin delivered 2 to 2.5 times greater total bioavailability for ampicillin and sulbactam than when each was used individually. Actual plasma or serum concentrations (measured in micrograms per milliliter) of ampicillin and sulbactam produced by sultamicillin were generally equivalent in rats, mice, and beagle dogs. Further studies also indicated that the components of sultamicillin were widely distributed in the various tissues of rats. These findings suggest that sultamicillin might be an effective agent against a variety of infections produced by both beta-lactamase-resistant and beta-lactamase-susceptible microorganisms.