[Glycol and Phosphate Depot Forms of 4- and/or 5-Modified Nucleosides Exhibiting Antibacterial Activity].

Resistance developed to the majority of drugs used to treat infectious diseases warrants the design of new compounds effective against drug-resistant strains of pathogens. Recently, several groups of modified nucleosides have been synthesized and showed significant antibacterial activity in vitro, but their further studies were difficult to undertake because of their low solubility in aqueous solutions. Nevertheless, new compounds, well soluble in water-organic solutions, were synthesized and found to be more effective in inhibiting the growth of Gram-positive bacteria and mycobacteria. The water-soluble forms of modified nucleosides under study were assumed to be their depot forms. To check the assumption, the compounds were tested for hydrolysis in various media and their molecular docking was performed into the active center of the putative target, Mycobacterium tuberculosis flavin-dependent thymidylate synthase ThyX. Computer modelling showed that the water-soluble analogs do not act as ThyX inhibitors, supporting the assumption of their depot nature. The compounds were resistant to chemical hydrolysis but were hydrolyzed when incubated with porcine liver carboxylesterase, human serum, or Staphylococcus aureus 209P. The results demonstrate that the compounds are most likely depot forms of modified nucleosides.

Development of Liposomal Forms of Modified Pyrimidine Nucleosides and Investigation of Their Antibacterial Properties.

Different phosphocholine-cardiolipin-2'-deoxyuridine inclusion complexes were developed, that allowed to compose a water-soluble form of nucleoside analogues with previously defined antituberculosis activity. It was found that the resulting liposomes effectively penetrated to the cells. The increase of cytotoxicity was undoubtedly indicative of accumulation of the nucleoside in the cell culture. The result proved the ability of the liposomes for delivery of the low-soluble compounds to the cells for further investigation of their efficacy. It was shown that treatment of the bacterial cells with the llposomes of the modified nucleosides did not affect the bacterial growth.

Antibiotic Activity of Probiotic Strain Bacillus subtilis 534 Against Clinical Isolates of Acinetobacter baumannii.

Probiotic strain Bacillus subtilis 534 is the base of sporobacterin, a pharmaceutical. In submerged culture it showed antibiotic activity against many of gram-positive and gram-negative bacteria and fungi. The spectrum of the antimicrobial activity of the culture fluid depended on the.cultivation time and aeration intensity. It was shown that component No. 1 of the antibiotic complex was effective against clinical isolates of Acinetobacter baumannii: 20 out of 24 isolates were susceptible to component No. 1, including 15 strains out of 16 panresistant isolates.

[Identification and Antagonistic Properties of the Soil Streptomycete Streptomyces sp. 100].

Aim: Determination of the taxonomic status of the soil streptomycete Streptomyces sp. 100 and study of its antagonistic properties against phytopathogenic and opportunistic human microorganisms. Methods: For the identification of the strain a set of conventional methods morphological and cultural, physiological and biochemical characteristics of the producer, as well as molecular genetic analysis of 16S rRNA gene were used. Streptomycete was cultivated on agar nutrient and liquid soy medium until the stationary phase of growth. The antagonistic activity of the strain was studied by agar diffusion method. Results: The study of morphological and cultural properties showed that Streptomyces sp. 100 formed the colonies with irregular edges protruding from the depressed center, straight sporophores were short, gathered in whorls; spores were oval, smooth shell dispute. Growing on agar medium (pH 6.8-7.4, temperature 28 °C, microaerophilic conditions) this strain formed mycelium of various colors: the air white, white-yellow, white-brown or substrate tan, cream and yellow, creamy carmine, yellow-brown. A soluble pigment was yellow and yellow-brown, while melanoid pigment was not detected. The morphological, cultural, physiological, biochemical and molecular genetic characteristics of the soil streptomycete let to identify it as Streptomyces netropsis (Finlay et al., 1951) IMV Ac-5025 (UCM Ac-2186) that is an active antagonist IMV Ac-5025 against plant pathogens. Growing on a surface of agaric nutrient media it inhibits phytopathogenic bacteria (Xanthomonas axonopodis pv. glycines 8609, Pseudomonas savastanoi pv. glycinea 8571, P. syringae pv. coronafaciens 9030) and fungi (Alternaria alternata 16814, Fusarium оxysporum 54201) zone of growth inhibition were 20 - 32 mm and 16 - 30 mm respectively. The supernatant of culture medium and the ethanol extract of biomass inhibited the growth of pathogenic bacteria and fungi. The most sensitive to action of a supernatant of cultural liquid were P. syringae pv. atrofaciens 7886 and Clavibacter michiganensis ssp. michiganensis 102, growth inhibition zones - 42 and 30 mm respectively. It should be noted that in the majority of cases the supernatant of cultural liquid suppressed growth of phytopathogenic bacteria in comparison with biomass extract more actively. At the same time only biomass extract inhibited the growth of P. syringae pv. coronafaciens 9060, P. corrugatа 9070, X. anoxopodis pv. glycines 9075, X. anoxopodis pv. glycines 8609 and Pantoea agglomerans 8490. Tolerant to metabolites of S. netropsis IMV Ac-5025 were P. syringae pv. atrofaciens 8291 and X. visicatoriae 7790. The extract of biomass S. netropsis IMV Ac-5025 inhibited growth of all studied strains of phytopathogenic fungi (A. alternata 16814, A. culmorum 00790, F. оxysporum 54201, F. tricinetum 00795, F. oxysporum n.33, Cladosporium herbarum 16863, Cochliobolus spicifas 16860, Nigrospora oryzae 16864). The supernatant of the cultural liquid also showed the oppressing action on fungi, except for Cladosporium herbarum 16863 and Cochliobolus spicifas 16860. The strain was almost ineffective against opportunistic human microorganisms (Escherichia coli ATCC 25922, Bacillus pumilus NCTC 8241, Staphylococcus aureus FDA 209P et al.). Conclusions: The lack of action of Streptomyces netropsis IMV Ac-5025 on the opportunistic human microorganisms and the active antagonism of phytopathogens, both, define potential its application for plant protection.

[Antimicrobial Properties of Eremoxylarin A Produced by Ascomycete of Sordariomycetes in Submerged Culture].

The fungal strain INA 01108 producing antibiotic substances with broad spectrum of antibacterial activity was isolated from the natural environment. By the morphological characteristics and DNA analysis it was shown to belong to Ascomycetes of Sordariomycetes. In submerged culture the strain produced at least four antibiotics. The major component of them was identified as eremophilane-type sesquiterpene eremoxylarin A. Eremoxylarin A is effective in vitro against grampositive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin group glycopeptide antibiotics resistant Leuconostoc mesenteroides VKPM B-4177. The efficacy and toxicity of eremoxylarin A was determined on a murine staphylococcal sepsis model. The dose of 6.25 mg/kg provided 100% recovery and survival of the animals, while the dose of 3.12 mg/kg was close to the ED50. The chemical structure of eremoxylarin A allows to modify the antibiotic and such studies may be relevant to design a less toxic derivative without loss of the valuable antimicrobial properties.

Complete Genome Sequences of Streptomyces albus Strain INA 01303.

Here, we report the complete genome sequence of Streptomyces albus strain INA 01303, which was isolated from the Salt Lake Tambukan (Russia). The genome consists of a linear 6,840,896-nucleotide chromosome. This strain is predicted to produce a range of novel secondary metabolites with antibiotic activity.

Development of Antimicrobial Therapy Methods to Overcome the Antibiotic Resistance of Acinetobacter baumannii.

The spread of antibiotic resistance among pathogens represents a threat to human health around the world. In 2017, the World Health Organization published a list of 12 top-priority antibiotic-resistant pathogenic bacteria for which new effective antibiotics or new ways of treating the infections caused by them are needed. This review focuses on Acinetobacter baumannii, one of these top-priority pathogens. The pathogenic bacterium A. baumannii is one of the most frequently encountered infectious agents in the world; its clinically significant features include resistance to UV light, drying, disinfectants, and antibiotics. This review looks at the various attempts that have been made to tackle the problem of drug resistance relating to A. baumannii variants without the use of antibiotics. The potential of bacteriophages and antimicrobial peptides in the treatment of infections caused by A. baumannii in both planktonic and biofilm form is assessed. Such topics as research into the development of vaccines based on the outer membrane proteins of A. baumannii and the use of silver nanoparticles, as well as photodynamic and chelate therapy, are also covered.

[Genotoxic and mutagenic activity of antineoplastic anthracyclines and their aglycones: study in two test-systems]. / Genotoksicheskaia i mutagennaia aktivnost' protivoopukholevykh antratsiklinov i ikh aglikonov: izuchenie v test-sistemakh.

Mutagenic (Ames tests) and genotoxic (SOS chromotest) activities of highly-efficient natural anthracycline monosaccharides possessing antitumor activity-daunorubicin (also known as daunomycin or rubomycin), doxorubicin (adriamycin), and carminomycin-were studied. At the same time, the hypothesis was tested that intercalation of the antibiotic moiety into the helix of cell DNA, which was mediated by the saccharide amino group, played a crucial role in genotoxicity of these anthracyclines. The hydrolysis products of these antibiotics (the corresponding aglycones) and aclacynomycin A (an anthracycline trisaccharide), as well as aclavinone (its derivative aglycone), were studied. All these compounds lacked the saccharide amino group necessary for intercalation. It was found that all anthracycline monosaccharides studied had a strong mutagenic effect on strain TA98 and a moderate effect on strain TA100 of Salmonella typhimurium. Aclacynomycin A was found to have no mutagenic effect on any strain. Lack of the glycoside amino group did not necessarily result in loss of mutagenic activity in the derivative aglycones of anthracycline monosaccharides: they exhibited moderate mutagenic activity in strain TA98 and low but significant activity in strain TA100. The S9 microsomal fraction did not alter the mutagenic activity of either anthracycline monosaccharides or their aglycones; however, it dramatically increased the mutagenic activity of aclavinone: correspondence between positive responses in Ames tests and the SOS chromotest was found. Apparently, the mutagenic activity of the substances studied in bacterial cells was mediated by inducing the SOS-repair process. If the compound contained the amino glycoside moiety, functional and structural precursors of the SOS response were formed via intercalation of the reagents into the DNA duplex; if the substance did not contain this moiety, the precursors were formed via ionic interaction.

[Hybridization of A-factor deficient mutants of Streptomyces griseus by means of fusion of protoplasts]. / Gibridizatsiia A-faktornedostatochnykh mutantov Streptomyces griseus putem sliianiia protoplastov.

Characteristics of 6 A-factor deficient mutants of S. griseus are presented. The common feature of the mutants was impairment of sporulation, formation of aerial mycelium and streptomycin synthesis. Pair-by-pair hybridization of the mutants was performed with protoplast fusion followed by regeneration. 9 pair couplings of the mutants were performed. In 3 of them sporulating recombinants were detected. The antibiotic production level in 70 hybrids was different and ranged from 0 to 1700 micrograms/ml. The morphological features of the colonies and the number of the spores formed were also different. The common feature of all the 70 sporulating hybrid strains was recovery of synthesis of A-factor, an endogenic regulator of S. griseus development. Therefore, in the A-factor deficient mutants impairment of A-factor synthesis was induced not by the plasmid elimination, as was suggested, but by mutation of separate genes.

[Selection of antibacterial therapy for treatment of infections in elderly patients]. / Vybor antibakterial'noi terapii pri lechenii infektsii u lits pozhilogo vozrasta.

Examination of 60 elderly outpatients with lower respiratory tract infections (LRTI) revealed that 73 per cent of the patients isolated the pathogen associations and only 27 per cent isolated the monocultures. Grampositive cocci including Streptococcus pneumoniae were isolated from 70 per cent of the patients, Haemophilus influenzae and H.parainfluenzae were isolated from 20 per cent of the patients and Acinetobacter spp., Citrobacter spp., Enterobacter spp., Proteus spp. and Pseudomonas aeruginsa were isolated from 10 per cent of the patients. The patients were treated with ciprofloxacin, cefaclor or amoxycillin/clavulanic acid. Ciprofloxacin proved to be the most efficient agent. The regimens of the ofloxacin use in a dose of 400 mg orally once a day or in a dose of 200 mg intravenously twice a day for 2-4 days followed by the oral use for 6-8 days in the treatment of 24 patients with LRTI hospitalized into a therapeutic unit were compared. it was shown (pharmacokinetically as well) that the regiment with the drug use in the single dose was more efficient. Lomefloxacin was suggested to be the most advantageous drug in the treatment of elderly patients with LRTI because of its easy use, practically no dependence of the pharmacokinetics on the patient age and almost no nephrotoxic action.

[Effect of low molecular weight regulators on the biosynthesis of rifamycin B by Amycolatopsis mediterranei strains]. / Vliianie nizkomolekuliarnykh reguliatorov na biosintez rifamitsina B shtammami Amycolatopsis mediterranei.

Formation of differentiation regulators of the A-factor group in representatives of Nocardia and Nocardia-like actinomyces: N. asteroides, N. brasiliensis, Amycolatopsis mediterranei and "Streptomyces listeri" was observed. The effect of the regulators of different nature (barbital, A-factor and B-factor) on biosynthesis of rifamycin B by A. mediterranei strains was studied. It was shown that the A-factor stimulated rifamycin B production in the adifferentiated low active variant isolated from a natural population of the active strain VNIIA 1713 of the rifamycin B-producing culture. B-Factor insignificantly inhibited biosynthesis of rifamycin B in the studied strains of A. mediterranei.

[Clinical and pharmacokinetic evaluation of ofloxacin under various regimens of administration in patients with bronchopulmonary infections]. / Klinicheskaia i farmakokineticheskaia otsenka ofloksatsina pri raznykh rezhimakh vvedeniia u bol'nykh s bronkholegochnoi infektsiei.

Ofloxacin was used in the treatment of 24 patients with chronic bronchitis or pneumonia at the background of chronic bronchopulmonary and cardiovascular diseases. The drug was administered in accordance with 2 regimens: orally in a dose of 400 mg once a day (group I) and intravenously in a dose of 200 mg twice a day for 2 to 4 days followed by the drug oral use in the same dosage for 6 to 8 days (group II). The trial included comparison of the treatment efficacy by a complex of clinicobacteriological indices, estimation of the drug pharmacokinetics under the two regimens and prediction of the drug concentrations in blood with the mathematical models. High clinical and bacteriological efficacies of ofloxacin were shown under both the regimens. The pathogen eradication under both the regimens was observed in 61.5 and 72.7 per cent of the cases in groups I and II respectively. Dependence of the ofloxacin blood concentrations in the patients on the dosage regimen was detected. The pharmacokinetic studies demonstrated the possible prediction of the drug blood concentrations after the multiple administrations based on the calculated parameters.

[A-Factor as a selective agent for isolation of the soil Gram-negative bacterium strain--the producent of an antibacterial antibiotic]. / A-Faktor kak selektivnyi agent dlia vydeleniia pochvennoi gramotritsatel'noi bakterii--produtsenta antibakterial'nogo antibiotika.

It was shown the stimulating role of A-factor on soil prokaryotes growth. Soil sample culturing on agar medium, containing A-factor, resulted in the colony forming units (CFU) increasing in comparison with culturing on the medium without this regulator. Gram-negative bacteria were the reason of CFU increasing; previously the effect of A-factor on bacteria of this group was not shown. Gram-negative rod bacterial strain No. 35 was isolated and shown that CFU number was approximately twice increased at A-factor concentration in agar medium 2 and 7 mcg/ml; high A-factor concentration up to 28 mcg/ml was not effective. Isolated strain No. 35 is the producer of antibiotic, effective against gram-positive bacteria.

[Treatment of lower respiratory tract infections in the elderly]. / Lecheniie infektsil nizhnikh dykhatel'nykh putel u lits pozhilogo vozrasta.

Sixty outpatients at the age of 65 to 75 years with exacerbated chronic bronchitis were treated with antibiotics: amoxycillin/clavulanic acid (20 patients), cefaclor (20 patients) and ciprofloxacin (20 patients). The treatment course in all the cases was 5 days. Bacteriological tests of the sputum specimens and estimation of the isolate antibiotic susceptibility by the disk diffusion method were applied to all the patients before and after the treatment. 73 per cent of the patients had mixed infection. The microflora mainly included various species of streptococci highly susceptible to the drugs (54 per cent) as well as highly susceptible strains of pneumococci and hemophilic bacilli (33 and 17 per cent respectively). Atypical microflora was detected in 10 per cent of the cases. Pseudomonas aeruginosa strains were isolated in 2 cases. Acinetobacter sp. slightly susceptible only to ciprofloxacin was isolated in 1 case. Citrobacter sp. slightly susceptible to cefaclor and moderately susceptible to ciprofloxacin was detected in 1 case. Enterobacter sp. moderately susceptible only to ciprofloxacin was isolated in 1 case. A positive factor was moderate susceptibility of Proteus mirabilis to all the three drugs. In 24 patients (the average age of 54.7 years) the pharmacokinetics of ofloxacin administered under 2 different regimens was studied. The drug was used in a single dose of 400 mg once a day (group 1) or in a dose of 200 mg twice a day (group II) followed by estimation of the drug concentration in the blood and sputum. The pathogen eradication was stated in 61.5 and 72.7 per cent of the patients in groups I and II, respectively. By the results of the treatment with the use of the above mentioned antibiotics in the elderly patients fluoroquinolones should be considered preferable from the clinical and pharmacoeconomic viewpoints.

[Antimicrobial activity of Laetiporus sulphureus strains grown in submerged culture]. / Antimikrobnaia aktivnost' shtammov Laetiporus sulphureus v usloviiakh glubinnogo kul'tivirovaniia.

Cultural conditions for growth and fruit body formation were elaborated to four strains of Laetiporus sulphureus isolated from nature. All strains demonstrated antimicrobial activity against a wide spectrum of gram-positive and gram-negative bacteria during agar and submerged cultivation including methicillin-resistant strain of Staphylococcus aureus (MRSA) and glycopeptide-resistant strain of Leuconostoc mesenteroides. Antifungal activity was not found. The level of antimicrobial activity during submerged cultivation reached maximum after seven days of growth on specific medium with soybean meal and corn liquid; the next four weeks its increasing was not so manifested. Antimicrobial activity correlated with orange pigment secretion and cultural liquid acidification to pH 2.0-2.8 that indicates on acid nature of synthesized products.

[The safety of ofloxacin]. / K voprosu o bezopasnosti ofloksatsina.

The data on a comparative study of ofloxacin arthrotoxicity in pediatric and adult patients are presented. The tolerability of ofloxacin used in various doses and treatment terms (acute and cumulative effects) was investigated in children. The impact of the patient pubertal age, sex, ofloxacin concentrations (Cmax above 4 micrograms/ml) and arthrological diseases (in adult patients) on the risk of the quinolone arthropathy was evaluated. Good tolerability of the various ofloxacin dosing regimens in both the adult and pediatric patients was shown.

[New antibiotics produced by Bacillus subtilis strains].

Two Bacillus subtilis strains isolated from the fruiting body of a basidiomycete fungus Pholiota squarrosa exhibited a broad range of antibacterial activity, including those against methicillin-resistant Staphylococcus aureus INA 00761 (MRSA) and Leuconostoc mes6nteroides VKPM B-4177 resistant to glycopep-> tide antibiotics, as well as antifungal activity. The strains were identified as belonging to the "B. subtilis" com- plex based on their morphological and physiological characteristics, as well as by sequencing of the 16S rRNA gene fragments. Both strains (INA 01085 and INA 01086) produced insignificant amounts of polyene antibiotics (hexaen and pentaen, respectively). Strain INA 01086 produced also a cyclic polypeptide antibiotic containing Asp, Gly, Leu, Pro, Tyr, Thr, Trp, and Phe, while the antibiotic of strain INA 01085 contained, apart from these, two unidentified nonproteinaceous amino acids. Both polypeptide antibiotics were new compounds efficient against gram-positive bacteria and able to override the natural bacterial antibiotic resistance.

A versatile synthesis of highly bactericidal Myramistin® stabilized silver nanoparticles.

Silver nanoparticles stabilized by a well-known antibacterial surfactant benzyldimethyl[3-(myristoylamino)propyl]ammonium chloride (Myramistin(®)) were produced for the first time by borohydride reduction of silver chloride sol in water. Stable aqueous dispersions of silver nanoparticles without evident precipitation for several months could be obtained. In vitro bactericidal tests showed that Myramistin(®) capped silver NPs exhibited notable activity against six different microorganisms-gram-positive and gram-negative bacteria, yeasts and fungi. The activity was up to 20 times higher (against E. coli) compared to Myramistin(®) at the same concentrations and on average 2 times higher if compared with citrate-stabilized NPs.