Antibiotiki最新文献

A new vector type was constructed on the basis of SLP 1.2 plasmid and the Kanr determinant of S. rimosus P3. It was shown that the determinant was capable of amplifying in the chromosomes of S. rimosus during its improvement for increasing the level of resistance to kanamycin. Cloning of the Kanr determinant was performed on the Pst I-A fragment of the SLP 1.2 plasmid in S. lividans 66. The Kanr determinant was expressed in the resulting hybrid plasmids, e. g. pSU 3, thus providing resistance of S. lividans to 20 micrograms/ml of kanamycin. As a result of repeated passages variants capable of growing in the presence of 50 000 micrograms/ml of the antibiotic were selected. The electrophoretic analysis of the total DNA fragments obtained after exposure to different endonucleases showed that they were identical to the respective fragments of the hybrid pSU 3 plasmid and amounted to approximately 40 per cent of the total DNA. The presence of the unique sites for the Bam HI, ClaI and SacI restriction endonucleases on the pSU 3 plasmid in an insignificant area and the relative stability (30-100 per cent) of the amplified variants allowed using it for cloning and amplification of DNA in Streptomyces. Plasmids were identified with the genetic and physical methods in 13 strains of the blue systematic group among the 72 strains studied. A multicopy plasmid with a molecular weight of 5.6 MD designated as pSB 24.1 was identified in the family of the plasmids of S. cyanogenus. The deletion and insertion variants of the pSB 24.1 plasmid were obtained. The comparative study of the properties of these plasmids revealed the areas insignificant for replication and maintenance of the pSB 24.1 plasmid and the area determining the Ltz+-phenotype. It was suggested that formation of the deletion and insertion variants of the pSB 24.1 plasmid was provided by the site specific recombination mechanisms. The presence of the unique sites for a number of the restriction endonucleases located in the insignificant area, the presence of the selective marker and the high transformation frequency allowed one to consider the multicopy pSB 24.1 plasmid an acceptable vector for cloning of DNA in Streptomyces.

The conditions for preparation and regeneration of the protoplasts of M. olivoasterospora were developed. It was found that effective formation of the protoplasts required preliminary cultivation of M. olivoasterospora in the medium containing glycine in a concentration inhibiting its growth at least by 60-80 per cent. The strains studied markedly differed in their sensitivity to glycine and were highly sensitive to it. The efficacy of the protoplast formation depended on the culture age and increased with the use of the lytic enzyme 3 of Cytophaga dissolvens. The possibility and advisability of the use of prolonged lysis of the Micromonospora cell walls were shown. A rich organic medium was used for regeneration of the protoplasts.

The possibility of L-transformation for two species of Rickettsia of the tick group (R. conorii and R. akari) was studied with light and electron microscopy. The experiments were performed on the cultures of L-cells (murine fibroblasts). Penicillin and vancomycin were used as the transforming agents. Electron microscopy revealed clear changes in the morphological structure of both species when the doses of penicillin and vancomycin were 50-100 and 250-1500 micrograms/ml, respectively. The antibiotics had a morphologically analogous effect on both species of Rickettsia. The resulting morphological structures were large oval spheroplast-like cells with significant expansion of the periplasmic space up to 1 X 1.75 micron under the effect of penicillin and 0.5 X 0.7 micron under the effect of vancomycin. R. akari was somewhat more sensitive to the antibiotics. Electron microscopy of the morphological changes in the Rickettsia induced by penicillin and vancomycin showed that they were similar to the changes observed in gram-negative bacteria on their L-transformation and to the penicillin forms of chlamydia (galprovia) and R. prowazekii. They may be considered as a phase of unbalanced growth and represent the initial stage of L-transformation.

The pharmacokinetics of bleomycetin, a new antitumor antibiotic prepared in the USSR, was studied microbiologically. The less the extent of the main tumor in the patients, the higher the antibiotic blood levels in them. This might be associated with the adsorption capacity of the tumor tissue. The dependence of the bleomycetin kinetics on the intensity of renal clearance was shown. The characteristics of the drug distribution in the blood after intravenous, intramuscular and intrapleural administration are presented.

A procedure for addition of the inoculum to the surface layer of semisynthetic agar was developed and recommended for the use in the assay of antibiotic sensitivity of microorganisms. The procedure differs from the alternative method of Barry et al. It is of special value when it is necessary to determine antibiotic sensitivity of the pathogens of highly contagious infections with the agar diffusion method.

The seasonal characteristic features of the efficacy of antioxidants in tetracycline affections of the liver were revealed in the experiments with 182 noninbred albino male rats. It was shown that sodium selenite had the most pronounced hepatoprotective effect in autumn and winter, while vitamin E was most effective in spring and summer. The combination of sodium selenite with vitamin E recovered impaired bile excretion in autumn, spring and summer. In winter, the recovery was less effective. It is concluded that the time factor plays a significant role in tetracycline hepatotoxicity and efficacy of antioxidants in tetracycline affections of the liver.

The structure of the causative agents isolated from patients with pyoinflammatory infections in 1980-1983 was analysed. It was shown that the surgical and urological infections were mainly caused by gram-negative bacteria. The other pyoinflammatory infections were mainly due to gram-positive cocci. A relatively high frequency of the strains of gram-negative bacteria, especially among Pseudomonas spp. and Enterobacter spp., resistant to aminoglycoside antibiotics, such as gentamicin, sisomycin and tobramycin with preserved sensitivity to amikacin and netilmicin in the majority of the strains was shown. Among the beta-lactam antibiotics cephotaxim and cephalotin were most active against gram-negative bacteria and staphylococci, respectively. The majority of the antibiotic resistant strains of gram-negative bacteria had analogous structures and levels of resistance to 7-12 antibiotics which might indicate the occurrence of 1-2 resistance plasmids among the clinical strains.

The association and conformational structure of the molecule of erythromycin in solutions of CCl4, C2Cl4 and CHCl3 were studied by the IR spectra in the region of v OH and vC = O. The analysis of the concentration and temperature changes showed that the erythromycin association was accounted for by the hydrogen linkage of OH ... O = C to the ester group. In the monomer molecule of erythromycin, all hydroxyl groups participated in the intramolecular hydrogen linkage. Band 3513 cm-1 belonged to the OH group in the five-membered cycles of OH ... O. Components 3500, 3530 and 3560 cm-1 of the wide band vOH were assigned to the cycles with OH ... N and OH ... O linkages of a larger size. The association was due to a break in a part of the intramolecular hydrogen linkages. Addition of strong acceptors of proton-hexamethanol and trioctylphosphinoxide to the solution resulted in attenuation of these bands and appearance of a strong band vOH of the erythromycin-acceptor complexes. In the presence of monochloroacetic acid in the solution of CHCl3 stoichiometric protonization of erythromycin was observed. The total acid was in the form of anion (vaCO-2 1610 cm-1) up to a ratio of 1:1. The protonization proceeded according to the nitrogen atom since the antibiotic spectrum in the region of vC=O did not change. Propionic acid titrated erythromycin in methanol solution and in mixtures of water and methanol up to a ratio of 1:5 (v/v). However, in the solution of CHCl3 equilibrium between the neutral and ionized molecules of the acid was seen.

The ability of various antibiotics to inhibit superoxide anion(O-2)-mediated formation of adrenochrome from adrenaline and recovery of cytochrome c by xanthine oxidase was studied. In the adrenaline system (pH 10.2), aminoglycosides might be arranged, according to the inhibitory effect, in the following order: monomycin greater than gentamicin greater than kanamycin greater than lincomycin greater than streptomycin. In the xanthine oxidase system (pH 7.8), that order was the following: monomycin greater than gentamicin greater than lincomycin greater than greater than kanamycin. It was suggested that the antibiotic inhibition of the O-2-dependent processes at the essential sites of metabolism and/or the antibiotic involvement into the process of free radical oxidation initiated by O-2 in the cells might be one of the mechanisms of the drug action and toxicity with respect to the host.

The study on the mutagenic activity of commercial synthetic cationic, anionic, amphoteric and nonionogenic surface active substances with antimicrobial properties demonstrated that they had no mutagenic effect on the microbial test systems, i.e. the histidine-deficient strains of Salmonella typhimurium on direct contact and under conditions of metabolic activation in vitro and in vivo. The cationoactive preparation B Kh-14 with the benzyl radical adjoining the nitrogen atom and linear hydrophobic C13H27 with the amide group having a pronounced antimicrobial effect on gram-positive and gram-negative bacteria and fungi showed no carcinogenic activity in the experiments with its long-term action on the urinary bladder mucosa and skin of rats, guinea-pigs and dogs.