rifampin and coumermycin

A new strategy for affinity-based drug delivery by modification of the drug rather than modification of the device is presented. Rifampin is modified to contain either one or two PEG-adamantane arms, and the drug release properties of dimeric coumermycin are compared to novobiocin with only one biding domain. The drugs are loaded into affinity-based and diffusion-only delivery platforms, the loading efficiency is calculated, and the release kinetics is determined in vitro. The presence of additional binding domains prolongs the release of antibiotics. Release rates differ little between modified and unmodified drug from the diffusion-only system. The results demonstrate the feasibility of custom-tuning drug delivery by multiplexing interactions with an affinity-based polymer platform.

Topics: Adamantane; Aminocoumarins; Binding Sites; Cyclodextrins; Delayed-Action Preparations; Diffusion; Drug Carriers; Drug Compounding; Humans; Hydrogels; Kinetics; Novobiocin; Polyethylene Glycols; Rifampin; Solutions; Spectroscopy, Fourier Transform Infrared; Staphylococcus epidermidis

At concentrations exceeding their MICs, novobiocin and coumermycin antagonised the bactericidal activities of nalidixic acid, ciprofloxacin, ofloxacin and norfloxacin against Escherichia coli KL16. The sensitivities to killing by ciprofloxacin of four mutant derivatives of KL16 carrying gyrA, nalB, nal24 or nal31 alleles were also antagonised by novobiocin. The activities of drug combinations were tested in nutrient broth, which allowed expression of 4-quinolone killing mechanisms A, B and C. They were also tested in nutrient broth plus rifampicin to inhibit mechanisms A and C of the 4-quinolones, and in phosphate-buffered saline, which inhibited mechanism A. Results showed that novobiocin antagonised mechanism C, but not B, of both ciprofloxacin and ofloxacin, but did not antagonise mechanism C of norfloxacin. A review of these and other data indicates that mechanism B may result from the activities of SOS error-prone DNA repair on an irreversibly-bound drug-gyrase-DNA complex, and that mechanism C is mediated via drug interaction with the B subunit of DNA gyrase.

Topics: Aminocoumarins; Anti-Infective Agents; Ciprofloxacin; Coumarins; DNA Topoisomerases, Type II; Escherichia coli; Genes, Bacterial; Microbial Sensitivity Tests; Mutation; Nalidixic Acid; Norfloxacin; Novobiocin; Ofloxacin; Rifampin

Mutations in the cysB and cysE genes of Escherichia coli K12 cause an increase in resistance to the gyrase inhibitor novobiocin but not to coumermycin, acriflavine and rifampicin. This unusual relationship was also observed among spontaneous novobiocin resistant (Novr) mutants: 10% of Novr mutants isolated on rich (LA) plates with novobiocin could not grow on minimal plates, and among those approximately half were cysB or cysE mutants. Further analyses demonstrated that cysB and cysE negative alleles neither interfere with transport of novobiocin nor affect DNA supercoiling.

Topics: Acetyltransferases; Acriflavine; Aminocoumarins; Bacterial Proteins; Cell Survival; Coumarins; DNA-Binding Proteins; Dose-Response Relationship, Drug; Drug Resistance, Microbial; Escherichia coli; Escherichia coli Proteins; Mutation; Novobiocin; Rifampin; Serine O-Acetyltransferase

The synthesis of inducible biodegradative threonine dehydratase of Escherichia coli increased several-fold in the presence of the DNA gyrase inhibitors, nalidixic acid and coumermycin. Temperature-sensitive gyrB mutants expressed higher levels of dehydratase as compared to an isogenic gyrB+ strain. Immunoblotting experiments showed increased synthesis of the dehydratase protein in the presence of gyrase inhibitors; addition of rifampicin and chloramphenicol to cells actively synthesizing enzyme preventing new enzyme production. Increased expression of dehydratase by gyrase inhibitors was accompanied by relaxation of supercoiled DNA.

Topics: Aminocoumarins; Blotting, Western; Chloramphenicol; Coumarins; DNA Topoisomerases, Type II; DNA, Superhelical; Enzyme Induction; Escherichia coli; Mutation; Nalidixic Acid; Rifampin; Temperature; Threonine Dehydratase; Topoisomerase II Inhibitors

The therapeutic activities of various antibiotics were evaluated in two murine models, i.e. the infection of normal mice as well as of nude mice. Coumermycin and rifampicin were the most active drugs, since not only inhibition of multiplication but also rapid elimination of Listeria monocytogenes could be achieved in normal and immunocompromised animals. Ampicillin was the most active beta-lactam antibiotic followed by azlocillin. The other beta-lactam antibiotics were definitely less active. The combination of ampicillin with gentamicin expressed no synergistic effect in vivo. Co-trimoxazole as well as ciprofloxacin were of moderate therapeutic value. The bacteriostatic drugs such as tetracycline and erythromycin were able to inhibit the bacterial multiplication in the normal mouse but not in the immunocompromised host. Thus an optimal drug for therapy of listeriosis does not yet exist.

Topics: Aminocoumarins; Animals; Anti-Bacterial Agents; Coumarins; Female; Lactams; Listeria monocytogenes; Listeriosis; Mice; Mice, Inbred Strains; Mice, Nude; Rifampin

The bactericidal interactions in vitro of two antibiotics active at the cell wall (teicoplanin and vancomycin) or two inhibitors of DNA gyrase (coumermycin and ciprofloxacin) combined with two inhibitors of protein synthesis (rifampicin and LM 427) were assessed against five Staphylococcus aureus strains. The S. aureus isolates included two oxacillin-sensitive and three oxacillin-resistant strains. The concentrations tested covered the range usually obtained in the serum with recommended doses. Coumermycin + rifampicin or LM 427, and ciprofloxacin + rifampicin or LM 427 were antagonistic when the concentration of either drug was higher than the MIC, and additive when sub-MIC concentrations were tested. Teicoplanin or vancomycin + rifampicin or LM 427 produced variable results. Of the synergic combinations, 14 of 15 included teicoplanin. Of the antagonistic combinations, 20 of 33 included LM 427. Antagonism with LM 427 was due to the higher intrinsic activity of LM 427 alone than teicoplanin, vancomycin or rifampicin. Teicoplanin (20 mg/l) + rifampicin or LM 427 (1 mg/l) was synergic (9/10).

Topics: Aminocoumarins; Anti-Bacterial Agents; Cell Wall; Ciprofloxacin; Coumarins; DNA-Directed RNA Polymerases; Drug Interactions; Glycopeptides; Humans; Rifabutin; Rifampin; Rifamycins; Staphylococcus aureus; Teicoplanin; Topoisomerase II Inhibitors; Vancomycin

Derepression of an uptake hydrogenase in Bradyrhizobium japonicum is dependent on a microaerophilic environment. Addition of DNA gyrase inhibitors during depression of hydrogenase specifically prevented expression of the hydrogenase enzyme. Antibodies to individual hydrogenase subunits failed to detect the protein after derepression in the presence of inhibitors, although there was no general inhibition of protein synthesis. The general pattern of proteins synthesized from 14C-labeled amino acids during derepression was not significantly different whether proteins were labeled in the presence or in the absence of gyrase inhibitors. In contrast, if transcription or translation was inhibited by addition of inhibitors of those functions, virtually no proteins were labeled during derepression. This indicated that most of the 14C-labeled proteins were synthesized de novo during derepression, synthesis of most proteins was unaffected by gyrase inhibitors, and the dependence of hydrogenase synthesis on gyrase activity was a specific one.

Topics: Aminocoumarins; Bacterial Proteins; Chloramphenicol; Coumarins; Gene Expression Regulation; Hydrogenase; Nalidixic Acid; Novobiocin; Rhizobiaceae; Rifampin; Topoisomerase II Inhibitors

The in vitro activity of coumermycin was tested against oxacillin-susceptible and resistant strains of Staphylococcus aureus and Staphylococcus epidermidis, and compared with that of penicillin G, oxacillin, minocyclin, erythromycin, vancomycin, teicoplanin, rifampicin and LM 427. The MICs were measured using the agar dilution method with an inoculum of 10(5) cfu/spot. Coumermycin was the most active antibiotic with MIC90 of 0.025-0.2 mg/l. The MICs of coumermycin remained unchanged by further incubation for 48 h. The combination of coumermycin with ciprofloxacin, an inhibitor of subunit A of the DNA gyrase, was studied by the time-kill curve method and resulted in a synergistic effect when subinhibitory concentrations of either antibiotic were used. The combination of coumermycin with rifampicin or LM 427 was antagonistic.

Topics: Aminocoumarins; Anti-Bacterial Agents; Ciprofloxacin; Coumarins; Drug Combinations; Microbial Sensitivity Tests; Quinolines; Rifabutin; Rifampin; Rifamycins; Staphylococcus aureus; Staphylococcus epidermidis

Mutants separately resistant to novobiocin, coumermycin, nalidixic acid, and oxolinic acid contained gyrase activity as measured in vitro that was resistant to the antibiotics, indicating that the mutations represented structural alterations of the enzyme. One Novr mutant contained an altered B subunit of the enzyme, as judged by the ability of a plasmid, pNov1, containing the mutation to complement a temperature-sensitive gyrase B mutation in Escherichia coli and to cause novobiocin resistance in that strain. Three other Novr mutations did not confer antibiotic resistance to the gyrase but appeared to increase the amount of active enzyme in the cell. One of these, novB1, could only act in cis, whereas a new mutation, novC, could act in trans. An RNA polymerase mutation partially substituted for the novB1 mutation, suggesting that novB1 may be a mutation in a promoter region for the B subunit gene. Growth responses of strains containing various combinations of mutations on plasmids or on the chromosome indicated that low-level resistance to novobiocin or coumermycin may have resulted from multiple copies of wild-type genes coding for the gyrase B subunit, whereas high-level resistance required a structural change in the gyrase B gene and was also dependent on alteration in a regulatory region. When there was mismatch at the novB locus, with the novB1 mutation either on a plasmid or the chromosome, and the corresponding wild-type gene present in trans, chromosome to plasmid recombination during transformation was much higher than when the genes matched, probably because plasmid to chromosome recombination, eliminating the plasmid, was inhibited by the mismatch.

Topics: Aminocoumarins; Coumarins; DNA Repair; DNA Topoisomerases, Type II; DNA, Bacterial; Drug Resistance, Microbial; Genes, Regulator; Genetic Complementation Test; Genetic Linkage; Haemophilus influenzae; Mutation; Nalidixic Acid; Novobiocin; Oxolinic Acid; Phenotype; Promoter Regions, Genetic; R Factors; Recombination, Genetic; Rifampin; Ultraviolet Rays