Antibiotiki最新文献

Metabolism and function of mouse phagocytes were studied experimentally under conditions of immunosuppression with biologically active substances. It was shown by the cytochemical methods with the use of cytophotometry that strong immunosuppression with azathioprin, prednisolone, especially with their combination induced inhibition of the enzymatic systems responsible for synthetic and energy processes in macrophages. Prodigiosan, a bacterial lipopolysaccharide, and lysozyme promoted elimination of the unfavourable effect of the immunosuppressors on macrophage metabolism, normalizing the decreased activity of certain enzymes and markedly activating the enzymes involved in detoxification and phagocytosis. The lysozyme effect did not depend on the type of drug immunosuppression. The efficiency of prodigiosan was the highest after administration of prednisolone or its combination with azathioprin. Its effect was lower after immunosuppression with azathioprin alone. During allotransplantation, prodigiosan also promoted the recovery of the leukocyte adsorption and digestive capacity impaired by prednisolone and tis combination with azathioprin. The differential use of the biologically active substances is a promising trend in control of complications due to immunosuppression therapy.

To identify the structure of virenomycin, a new antitumor antibiotic consisting of components V and M, its acetyl and permethyl derivatives, as well as products of acid methanolysis and their derivatives were obtained. The IR-, NMR- and mass-spectra of the above compounds are presented. Based on an analysis of the spectral data the structure of virenomycin is suggested.

A model for determination of the admixture concentration in the secondary mother solution was developed. The concentration was determined depending on the solvent volume used for repulping the precipitate and on the impurity level of the initial antibiotic paste. When the values of X1 and X2 are known it is possible to estimate the amount of the admixtures remaining in the paste layer after separation of the secondary mother solution with regard to the volume of the latter in the precipitate pores. Optimization of paste repulping should be considered in combination with displacement washing and the apparatus used for separation of the phases, as well as the requirements for the purity level of the finished product.

The cell walls and peptidoglycans of two mutant strains, Streptomyces chrysomallus var. carotenoides and Streptomyces chrysomallus var. macrotetrolidi, were studied. The strains are organisms producing carotenes and antibiotics of the macrotetrolide group. By the qualitative composition of the peptidoglycans the mutants belong to Streptomyces and are similar. Their glycan portion consists of equimolar quantities of N-acetyl glucosamine and muramic acid. The peptide subunit is presented by glutamic acid, L, L-diaminopimelic acid, glycine and alanine. The molar ratio of alanine is 1.2-1.3. The mutant strains differ in the content of carbohydrates, total phosphorus and phosphorus belonging to teichoic acids. Teichoic acids of the cell walls of the both strains are of the ribitolhosphate nature. The cell walls of the mutants contain polysaccharides differing from teichoic acids and consisting of glucose, galactose, arabinose and fucose. The influence of the cell wall composition of the mutant strains on their morphology and metabolism and comparison of the data relative to the mutant strains with those relative to the starting strain are discussed.

The time-course of the oleandomycin content in the mycelium and fermentation broth-filtrate was studied by the microbiological assay at different periods of cultivation of strains 471 and 961 in fermenters and flasks containing a rich soybean-corn medium. It was shown that centrifugation of the mycelium over the sucrose density gradient induced a 25-80 per cent decrease in its moist weight at the expense of removal of the admixture components of the rich medium. Addition of glucose (2 per cent) to the culture-grown in a lactose medium by the 72nd hour of fermentation had no effect on further increase of the cell biomass. However, it lowered the content of the mycelium-fixed and excreted antibiotic at all the subsequent fermentation periods. The content of oleandomycin in the untreated mycelium was only 0.36 per cent of its content in the fermentation broth filtrate. After centrifugation of the mycelium over the sucrose density gradient and its intensive washing with distilled water the content of the mycelium-fixed antibiotic decreased still more. The time-course of the content of the mycelium-fixed and excreted oleandomycin was characterized by the presence of two activity peaks; by the 80-110th and by the 140-170th hour of cultivation.

The MICs and MBCs (minimum bactericidal concentration) of 6 antibiotics (benzylpenicillin, oxacillin, cephalothin, ristomycin, erythromycin and lincomycin) for 50 strains of group A streptococci were determined with serial dilutions in a liquid medium (the medium for isolation of streptococci of the I. I. Mechnikov Moscow Research Institute of Vaccines and Sera) followed by volumetric platings on a solid medium (the same medium supplemented with 1.5 per cent agar). The results are discussed in relation to the problem of Streptococci tolerance to the bactericidal effect of the antibiotics.

The use of benzylpenicillin and ampicillin in combination with sulfalen or sulfadimethoxine increased the levels of the penicillins and sulfalen in some organs and tissues of rats. This was accompanied by a rise in the concentration gradients of the drugs. It is concluded that the combined use of the penicillins and sulfanilamides determines their increased penetration from the blood into other organs and tissues of the host.

The results of the comparative study on microbiological and chemical quantitative determination of kanamycin sulfate in the ophthalmic films with the collagen base are presented. The intraocular films prepared with the use of 1 per cent collagen solution contain dexamethasone and kanamycin. The agar diffusion method with Bacillus pumilus NCTC 8241 as the test microbe and the photocolorimetric method based on estimation of the optical density of the colored compound formed after acid hydrolysis of kanamycin with orcinol and ferric chloride were used for the quantitative determination of kanamycin. The results of the quantitative determinations of kanamycin in the films with the two methods did not differ significantly. However, the error of the microbiological method was +/- 3,75 per cent, whereas that of the chemical method was +/- 1.23 per cent or approximately 3 times lower. The time of the analysis decreased from 24 to 1.5-2 h. Moreover, the chemical method is simple and readily reproducible.

The properties and origin of multiple resistant strains of Enterobacteriaceae found in the intestine and nasopharynx of infants admitted to the hospital for premature infants were studied. The strains of E. coli of different serovars isolated at various periods contained similar conjugative R plasmids with a molecular weight of 80 Md belonging to the O incompatibility group controlling resistance to kanamycin and physically independent small plasmids controlling resistance to ampicillin (7 Md) and streptomycin-sulfanilamides (4 Md). Multiple drug resistance in the strains of K. pneumoniae was controlled by single large (100-120 Md) plasmid cointegrates with 6-8 resistance markers. Such cointegrates consisted of several potentially independent plasmids, sometimes dividing on transformation of plasmid DNA of the recipient strains of E. coli K12. The small plasmids controlling resistance to ampicillin and streptomycin-sulfanilamides similar to the respective plasmids of E. coli were the constant components of the plasmids cointegrates. The multiple drug resistance in the above strains was combined with high capacity for colonization in premature infants. The medical staff and mothers were the sources of bacterial strains with single plasmids controlling definite types of resistance. It is suggested that the multiple resistant strains of Enterobacteriaceae are formed in hospital as a result of accumulation of the plasmids or plasmid markers and selection. One of the conditions for successive acquisition of new plasmid markers by definite bacterial strains was their high capacity for colonization in patients, which provided constant contacts and genetic exchange of such strains with a wide range of immigrant strains during colonization in the newly admitted patients.